1 Introduction

1.1       Background

1.1 Background

Anatec was commissioned by SSE Renewables Developments (UK) Limited (“SSE Renewables” (SSER)) to undertake a Navigational Risk Assessment (NRA) for the proposed Berwick Bank Wind Farm (hereafter the ‘Project’). The NRA has been undertaken with respect to the offshore components of the Project (hereafter, the ‘Proposed Development’) comprising the Proposed Development array area and the Proposed Development export cable corridor. This NRA presents information on the Proposed Development relative to the existing and estimated future navigational activity and forms an annex to volume 2, chapter 13 of the offshore Environmental Impact Assessment (EIA) Report.

1.2       Navigational Risk Assessment

1.2 Navigational Risk Assessment

Environmental Impact Assessment is a process which identifies the environmental effects of a project, both adverse and beneficial. An important requirement of the EIA for offshore projects is the NRA. Following the Maritime and Coastguard Agency’s (MCA) Marine Guidance Note (MGN) 654 (MCA, 2021), this NRA includes:

• Outline of methodology applied in the NRA including relevant guidance;
• Summary of consultation undertaken with shipping and navigation stakeholders;
• Lessons learnt from previous offshore wind farm developments;
• Summary of Project Design Envelope (PDE) relevant to shipping and navigation;
• Overview of existing environment including:
  • Navigational features;
  • Meteorological and oceanographic conditions;
  • Emergency response resources;
  • Historical maritime incidents; and
  • Vessel traffic movements.
• Implications for marine navigation and communication equipment;
• Cumulative and transboundary overview;
• Overview of anticipated future case vessel traffic;
• Assessment of navigational risk pre and post construction of the Proposed Development including collision and allision risk modelling;
• Hazard identification for further assessment in volume 2, chapter 13;
• Identification of embedded mitigation measures; and
• Completion of the MGN 654 Checklist (see Appendix A).

Potential hazards have been considered for each phase of the Proposed Development as follows:

• Construction;
• Operation and maintenance; and
• Decommissioning.

The assessment of the Proposed Development is based on a PDE, an approach which is standard practice for offshore wind farm developments given the potential for findings from further site investigations (to be undertaken post consent) and advancements in technology. The PDE includes conservative assumptions to form a maximum design scenario which is considered and assessed for all hazards on the basis that any deviation from the maximum design scenario (but still within the parameters of the PDE) will result in the risk of any relevant hazards being no greater than that assessed using the maximum design scenario. Further details on the PDE are provided in section 6.

2       Guidance and Legislation

2 Guidance and Legislation

2.1       Legislation

2.1 Legislation

As part of the EIA Directive (2011/92/European Union (EU), as amended by Directive 2014/52/EU) (which remains applicable following EU Exit), an EIA Report is required to support the application for the Section 36 consent for the Project. The MCA require that, as part of the EIA Report, an NRA is undertaken to “inform the shipping and navigation chapter of the EIA Report” (MCA, 2021).

2.2       Primary Guidance

2.2 Primary Guidance

The primary guidance documents used during the assessment are the following:

• MGN 654 (Merchant and Fishing) Safety of Navigation: Offshore Renewable Energy Installations (OREIs) – Guidance on UK Navigational Practice, Safety and Emergency Response and its annexes (MCA, 2021); and
• Revised Guidelines for FSA for Use in the Rule-Making Process (International Maritime Organization (IMO), 2018).

MGN 654 highlights issues that shall be considered when assessing the potential effect on navigational safety from offshore renewable energy developments proposed in United Kingdom (UK) internal waters, territorial sea or Renewable Energy Zones (REZ).

MGN 654 includes several annexes including the Methodology for Assessing the Marine Navigational Safety & Emergency Response Risks of Offshore Renewable Energy Installations (OREI) which the MCA require to be used as a template for preparing NRAs. The methodology is centred on risk management and requires a submission that shows that sufficient controls are, or will be, in place for the assessed risk to be judged as broadly acceptable or tolerable with mitigation (see section 3.2). In both volume 2, chapter 13 and the NRA, the base and future case levels of risk have been identified as well as the mitigation measures required to ensure the future case remains broadly acceptable, or tolerable with mitigation.

2.3       Other Guidance

2.3 Other Guidance

Other guidance documents used during the assessment include:

• MGN 372 (Merchant and Fishing) Offshore Renewable Energy Installations (OREI): Guidance to Mariners Operating in the Vicinity of UK OREIs (MCA, 2008);
• International Association of Marine Aids to Navigation and Lighthouse Authorities (IALA) Recommendation O-139 on The Marking of Man-Made Offshore Structures (IALA, 2021 (a));
• IALA Guidance G1162 The Marking of Offshore Man-Made Structures (IALA, 2021 (b)); and
• The Royal Yachting Association’s (RYA) Position on Offshore Renewable Energy Developments: Paper 1 (of 4) – Wind Energy (RYA, 2019).

2.4       Lessons Learnt

2.4 Lessons Learnt

There is considerable benefit for the Applicant in the sharing of lessons learnt within the offshore industry. The NRA, and in particular the risk assessment undertaken in volume 2, chapter 13, includes general consideration for lessons learnt and expert opinion from previous offshore wind farm developments and other sea users, capitalising upon the UK’s position as a leading generator of offshore wind power.

Data sources for lessons learnt include the following:

• Sharing the Wind – Recreational Boating in the Offshore Wind Strategic Areas (RYA and CA, 2004);
• Results of the Electromagnetic Investigations (MCA and QinetiQ, 2004);
• Offshore Wind Farm Helicopter Search and Rescue Trials Undertaken at the North Hoyle Wind Farm (MCA, 2005);
• Interference to Radar Imagery from Offshore Wind Farms (Port of London Authority (PLA),2005);
• Navigational Risk Assessment Phase 1 Offshore Wind Farms Project Alpha and Project Bravo (Anatec, 2012);
• Regional Cumulative Shipping and Navigational Review – Outer Firth of Forth and Tay Wind Farm Developments (Anatec, 2012);
• Strategic Assessment of Impacts on Navigation of Shipping and Related Effects on Other Marine Activities Arising from the Development of Offshore Wind Farms in the UK Renewable Energy Zone (REZ) (Anatec and The Crown Estate (TCE), 2012);
• Offshore Wind and Marine Energy Health and Safety Guidelines (RenewableUK, 2014);
• Influence of UK Offshore Wind Farm Installation on Commercial Vessel Navigation: A Review of Evidence (Anatec, 2016);
• Navigational Risk Assessment Addendum (Appendix 12A) (Anatec, 2018); and
• G+ Global Offshore Wind Health & Safety Organisation 2020 Incident Data Report (G+, 2021).

3       Navigational Risk Assessment Methodology

3 Navigational Risk Assessment Methodology

3.1       Formal Safety Assessment Methodology

3.1 Formal Safety Assessment Methodology

A shipping and navigation user can only be affected by a hazard if there is a pathway through which a hazard can be transmitted between the source activity (cause) and the user. In cases where a user is exposed to a hazard, the overall severity of consequence to the user is determined. This process incorporates a degree of subjectivity. The assessments presented herein for shipping and navigation users have considered the following criteria:

• Baseline data and assessment;
• Expert opinion;
• Outputs of the Hazard Workshop;
• Level of stakeholder concern;
• Time and/or distance of any deviation;
• Number of transits of specific vessel and/or vessel type; and
• Lessons learnt from existing offshore developments.

With regards to commercial fishing vessels, the methodology and assessment considers hazards to commercial fishing vessels in transit. A separate methodology and assessment have been applied in volume 2, chapter 12 to consider hazards to commercial fishing vessels related to commercial fishing activity (rather than commercial fishing vessels in transit).

3.2       Formal Safety Assessment Process

3.2 Formal Safety Assessment Process

The IMO Formal Safety Assessment (FSA) process (IMO, 2018) (the FSA process) as approved by the IMO in 2018 under Maritime Safety Committee (MSC) – Marine Environment Protection Committee (MEPC).2/circ. 12/Rev.2 has been applied to the risk assessment in volume 2, chapter 13 and is considered in this NRA.

The FSA process is a structured and systematic methodology based upon risk analysis and Cost Benefit Analysis (CBA) (if applicable) to reduce risks to As Low as Reasonably Practicable (ALARP). There are five basic steps within this process as illustrated in Figure 3.1   Open ▸ and summarised in the following list:

• Step 1 – identification of hazards (a list is produced of hazards prioritised by risk level specific to the problem under review);
• Step 2 – risk analysis (investigation of the causes and initiating events and consequences of the more important hazards identified in Step 1);
• Step 3 – risk control options (identification of measures to control and reduce the identified hazards);
• Step 4 – CBA (identification and comparison of the benefits and costs associated with the risk control options identified in Step 3); and
• Step 5 – recommendations for decision-making (defining of recommendations based upon the outputs of Steps 1 to 4).

Figure 3.1 Flow Chart of the FSA Methodology (IMO, 2018)

3.2.1        Hazard Workshop Methodology

A key tool used when undertaking an NRA is the Hazard Workshop which ensures that all risks are identified and qualified in agreement with relevant consultees prior to assessment within the Offshore EIA Report. Risks (and the determined qualification) are recorded via the hazard log which is presented in full in Appendix B.

Table 3.1   Open ▸ and Table 3.2 identify how the severity of consequence and the frequency of occurrence has been defined within the hazard log, respectively.

Table 3.1 Severity of Consequence Ranking Definitions

Table 3.2 Frequency of Occurrence Ranking Definitions

An aggregate of the severity of consequence (Table 3.1) and frequency of occurrence (Table 3.2) provide the level of risk for each hazard; the method for undertaking this aggregation is through use of a tolerability matrix, as presented in Table 3.3   Open ▸ . The risk of a hazard is defined as Broadly Acceptable (low risk), Tolerable (intermediate risk), or Unacceptable (high risk).

Once identified, the risk of a hazard is assessed to ensure it is ALARP. Further risk control measures may be required to further mitigate a hazard in accordance with the ALARP principle. Unacceptable risks are not considered to be ALARP.

Outputs of the hazard log have been used as evidence to support and refine the assessment undertaken in volume 2, chapter 13.

Table 3.3 Tolerability Matrix and Risk Rankings

3.3       Cumulative Risk Assessment Methodology

3.3 Cumulative Risk Assessment Methodology

The hazards identified in the FSA are also assessed for cumulative risks with other projects and proposed developments within the cumulative risk assessment. Given the varying type, status and location of developments, different scenarios have been considered in the cumulative risk assessment, which allocates developments into the scenarios depending upon the following criterion:

• Development status;
• Distance from the Proposed Development;
• Level of interaction with baseline traffic relevant to the Proposed Development;
• Level of concern raised during consultation; and
• Data confidence.

The scenarios and associated level of assessment undertaken for each, are summarised in Table 3.4   Open ▸ . Given the level of interest during consultation in the cumulative scenario, a detailed qualitative and quantitative (where applicable) approach to the cumulative risk assessment has been applied for each scenarios.

The maximum distance within which developments are considered for the cumulative risk assessment is 50 nm from the Proposed Development array area on the basis that there is not considered to be a direct pathway between the Proposed Development and any development beyond 50 nm from the Proposed Development array area. This distance is standard within NRAs and provides a good overview of cumulative traffic patterns.

An aggregate of the criterion can determine the relevant scenario(s) for each development. For example, if a development is located within 50 nm of the Proposed Development array area but does not impact a main commercial route passing within 1 nm of the Proposed Development array area and has low data confidence it may still be screened out of the cumulative risk assessment.

For offshore wind farms and in the context of shipping and navigation, the term ‘under construction’ indicates that offshore construction was ongoing at the time of the baseline being established and a buoyed construction area is present. The term ‘pre-construction’ indicates that a development has been consented and has a Contract for Difference (CfD) secured. The term ‘consented’ indicates that a development has been consented but does not have a CfD secured.

Projects meeting the assessment criteria are detailed in section 14.1.

Table 3.4 Cumulative Risk Assessment Development Screening Scenarios

3.4       Study Areas

3.4 Study Areas

3.4.1        Proposed Development Array Area

A 10 nm buffer has been applied around the Proposed Development array area (hereafter the ‘Proposed Development array area shipping and navigation study area’) as shown in Figure 3.2   Open ▸ . This study area has been defined to provide local context to the analysis of risks by capturing the relevant routes and vessel traffic movements within, and in proximity to, the Proposed Development array area. A 10 nm study area has been used within the majority of UK offshore wind farm NRAs and is suitable for collection of radar data.

Figure 3.2 Overview of Shipping and Navigation Study Areas

3.4.2        Proposed Development Export Cable Corridor

A 2 nm buffer has been applied around the Proposed Development export cable corridor (hereafter the ‘Proposed Development export cable corridor shipping and navigation study area’) as shown in Figure 3.2   Open ▸ . As with the Proposed Development array area shipping and navigation study area, this study area has been defined to capture relevant users and their movements within, and near, the Proposed Development export cable corridor. The Proposed Development export cable corridor shipping and navigation study area covers the area between the Mean Low Water Springs (MLWS) – marked on Figure 3.2   Open ▸ – and the boundary of the Proposed Development array area.

4       Consultation

4 Consultation

4.1       Stakeholders Consulted in Navigational Risk Assessment Process

4.1 Stakeholders Consulted in Navigational Risk Assessment Process

Key shipping and navigation stakeholders have been consulted in the NRA process. The following stakeholders have been consulted directly in meetings including the Hazard Workshops, noting that due to restrictions incurred by the COVID-19 pandemic, all meetings have been conducted via teleconferencing:

• MCA;
• Northern Lighthouse Board (NLB);
• UK Chamber of Shipping;
• RYA Scotland;
• Cruising Association (CA);
• Evergas;
• Fishermen’s Mutual Association (FMA) including representation of Scottish Fishermen’s Federation (SFF);
• Royal National Lifeboat Institution (RNLI);
• Forth Ports;
• Intrada;
• Regional Inshore Fisheries Group;
• Scottish Whitefish Producers Association;
• Fishing Industry Representatives (FIR) for ‘Borders to Cove, ‘Port Seton’, and ‘Montrose and Arbroath’;
• INEOS; and
• Shell.

Additionally, the Forth Yacht Clubs Association, Royal Northumberland Yacht Club and Regular Operators have been consulted via email correspondence. The following stakeholders were also contacted but did not provide any feedback:

• Tay Yacht Clubs Association;
• Montrose Port Authority;
• Arbroath Harbour;
• Pittenweem Harbour;
• Eyemouth Harbour Trust;
• Dunbar Harbour Trust; and
• Aberdeen Harbour Board.

As well as consulting with the organisations outlined in section 4.1, 24 Regular Operators identified from the vessel traffic surveys and long-term vessel traffic data were provided with an overview of the Project and offered the opportunity to provide feedback. Specific questions were included to aid Regular Operators wishing to make a response, including in relation to changes in routeing, adverse weather routeing and the cumulative scenario. The Regular Operator letter is presented in full in Appendix C.

The full list of Regular Operators identified and subsequently contacted[1] is provided below:

• Amasus Shipping;
• Arklow Shipping;
• EemsWerken;
• Evergas;
• Fletcher Group;
• Fred. Olsen Cruise Lines;
• Harren-Partner;
• HAV Ship Management;
• Intrada Ship Management;
• James-Fisher;
• John T. Essberger;
• Maersk;
• MF Shipping Group;
• North Star Shipping;
• Peak Group;
• Solstad;
• Uni Tankers;
• Unigas;
• Universal Africa Lines;
• Vroon;
• Whitaker Tankers; and
• Wilson.

Evergas, HAV Ship Management, North Star Shipping and Intrada Ship Management provided feedback directly, as summarised in the relevant entries in Table 4.1   Open ▸ .

4.2       Consultation Responses

4.2 Consultation Responses

Various responses have been received from stakeholders during consultation undertaken in the NRA process including during the Hazard Workshop, other consultation meetings, via email correspondence and through the Scoping Opinion for the 2020 Berwick Bank (Marine Scotland – Licensing Operations Team (MS-LOT), 2021)[2]. The key points and where they have been addressed in the NRA or volume 2, chapter 13 are summarised in Table 4.1   Open ▸ .

Table 4.1 Summary of Key Points Raised During Consultation

4.3       Hazard Workshops

4.3 Hazard Workshops

A key element of the consultation undertaken was the Hazard Workshops, meetings of local and national marine stakeholders to identify and discuss potential shipping and navigation hazards. Using the information gathered from the first Hazard Workshop, a hazard log was produced to be used as input into the risk assessment undertaken in volume 2, chapter 13. Using the information gathered from the second Hazard Workshop – following changes to the extent of the Proposed Development array area – the hazard log was updated.

This ensured that expert opinion and local knowledge was incorporated into the hazard identification process and that the hazard log was site-specific.

4.3.1        Hazard Workshop Attendance

The first Hazard Workshop was held via teleconferencing (due to restrictions incurred by the COVID-19 pandemic) on 28 September 2021 and was attended by all of the organisations listed below:

• MCA;
• NLB;
• UK Chamber of Shipping;
• RYA Scotland;
• CA;
• Evergas;
• FMA including representation of SFF;
• RNLI;
• Forth Ports;
• INEOS; and
• Shell.

Other Regular Operators were also given the opportunity to attend the first Hazard Workshop.

The second Hazard Workshop was held via teleconferencing on 27 July 2022 and was attended by all of the organisations listed below:

• MCA;
• NLB;
• UK Chamber of Shipping;
• RYA Scotland;
• FMA including representation of SFF;
• RNLI;
• Forth Ports;
• Scottish Whitefish Producers Association;
• FIR for ‘Eyemouth to Cove’, ‘Port Seton’, and ‘Montrose and Arbroath’; and
• Royal Northumberland Yacht Club.

4.3.2        Hazard Workshop Process and Hazard Log

During the Hazard Workshops, key maritime hazards associated with the construction, operation and maintenance and decommissioning of the Proposed Development were identified and discussed. Where appropriate, hazards were considered by vessel type to ensure risk control options could be identified on a type-specific basis.

Following the first Hazard Workshop, the risks associated with the identified hazards were ranked in the hazard log based upon the discussions held during the workshop. Where appropriate, mitigation measures were identified, including any additional measures required to reduce the risks to ALARP. The hazard log was then provided to the Hazard Workshop attendees for comment.

Following the second Hazard Workshop, the hazard log was updated based on reconsideration of the previously identified hazards and associated risks during the workshop. The hazard log was again provided to the Hazard Workshop attendees for comment and their feedback incorporated into the NRA.

The hazard log has been used to inform the risk assessment undertaken in volume 2, chapter 13 and is presented in full in Appendix B.

5       Data Sources

5 Data Sources

This section summarises the main data sources used to characterise the shipping and navigation baseline relative to the Proposed Development.

5.1       Summary of Data Sources

5.1 Summary of Data Sources

The main data sources used in assessing the shipping and navigation baseline relative to the Proposed Development are outlined in Table 5.1   Open ▸ .

Table 5.1 Data Sources Used to Inform Shipping and Navigation Baseline

5.2       Vessel Traffic Surveys

5.2 Vessel Traffic Surveys

The vessel traffic surveys were undertaken in agreement with the MCA and NLB. Two 14-day AIS, radar, and visual observation surveys undertaken in summer 2022 (2 to 16 August 2022) and winter 2021 (11 to 24 January 2021) have been considered within the baseline for a total of 28 full days, with an earlier survey undertaken in summer 2020 and long-term dataset from 2019 used as validation (see Appendix E and Appendix F).

A number of vessel tracks recorded during the Proposed Development array area survey periods were classified as temporary (non-routine), such as the tracks of the survey vessel, other non-routeing survey vessels and vessels associated with the construction of Neart na Gaoithe (NnG) and Seagreen. These have therefore been excluded from the analysis.

The dataset is assessed in full in section 10.

5.3       Long-Term Vessel Traffic Data

5.3 Long-Term Vessel Traffic Data

Long-term vessel traffic data consisting of AIS covering 12 months in 2019 was collected from coastal receivers. Taking into account the distance offshore of the Proposed Development array area, the long-term vessel traffic data is considered to be comprehensive for the Proposed Development array area shipping and navigation study area. The assessment of this dataset allowed seasonal variations to be captured and any tangible effects of the COVID-19 pandemic to be observed.

The dataset is assessed in full in Appendix E.

5.4       Data Limitations

5.4 Data Limitations

5.4.1        Automatic Identification System Data

For the purposes of the NRA, it has been assumed that vessels under an obligation to broadcast information via AIS have done so, both in the vessel traffic surveys and long-term vessel traffic data. It has also been assumed that the details broadcast via AIS (such as vessel type and dimensions) are accurate unless clear evidence to the contrary was identified during Anatec’s thorough quality assurance of the data.

5.4.2        Vessel Traffic Data for Proposed Development Export Cable Corridor

The MCA and NLB were content with the methodology for vessel traffic data collection. This method used only the AIS dataset to characterise vessel movements within the Proposed Development export cable corridor shipping and navigation study area. Consequently, this dataset has limitations associated with non-AIS targets.

5.4.3        COVID-19 Pandemic

It is widely accepted that the COVID-19 pandemic has had a substantial effect on shipping movements globally. Therefore, the vessel traffic survey data collected in winter 2021 may be influenced by COVID-19 pandemic. However, in line with best practices the Applicant has agreed the approach to data collection with relevant stakeholders, including the MCA.

Additionally, long-term vessel traffic data predating the COVID-19 pandemic has been used as a secondary source for characterising vessel traffic movements. A 12-month dataset covering 2019 has been referenced where relevant in the characterisation of the vessel traffic baseline. Analysis of the dataset in full is presented in Appendix E.

5.4.4        Historical Incident Data

Although all UK commercial vessels are required to report accidents to the Marine Accident Investigation Branch (MAIB), this is not mandatory for non-UK vessels unless they are in a UK port, within 12 nm of territorial waters (noting that the Proposed Development array area is located approximately 18 nm offshore at the closest point), or carrying passengers to a UK port. There are also no requirements for non-commercial recreational craft to report accidents to the MAIB.

The RNLI incident data cannot be considered comprehensive of all Incidents in the shipping and navigation study areas. Although hoaxes and false alarms are excluded, any incident to which a RNLI resource was not mobilised has not been accounted for in this dataset.

5.4.5        United Kingdom Hydrographic Office Admiralty Charts

The UKHO Admiralty Charts are updated periodically, and therefore the information shown may not reflect the real-time features within the region with total accuracy. For aids to navigation, only those charted and considered key to establishing the shipping and navigation baseline are shown.

During consultation, input has been sought from relevant stakeholders regarding the navigational features baseline. Navigational features are based upon the most recently available UKHO Admiralty Charts and Sailing Directions at the time of writing.

6       Project Design Envelope Relevant to Shipping and Navigation

6 Project Design Envelope Relevant to Shipping and Navigation

The NRA reflects the PDE, which is outlined in full in volume 2, chapter 3. The following subsections outline the maximum extent of the Proposed Development for which any shipping and navigation hazards are assessed.

6.1       Proposed Development Boundaries

6.1 Proposed Development Boundaries

6.1.1        Proposed Development Array Area

The Proposed Development array area is located approximately 30 nm (56 km) east of the entrance to the Firth of Forth, largely covering the Marr Bank in the western half, and partially covering the Berwick Bank at the south-eastern extent. The total area covered by the Proposed Development array area is approximately 294 square nautical miles (nm2) (1,008 square kilometres (km2)) with water depths ranging between 34 and 64 m below Chart Datum (CD).

All surface piercing structures (wind turbines and offshore substation platforms) will be located entirely within the Proposed Development array area, inclusive of blade overfly. The coordinates defining the boundary of the Proposed Development array area are illustrated in Figure 6.1   Open ▸ and provided in Table 6.1   Open ▸ . During no phase of the development will the Proposed Development array area be designated as an Area to Be Avoided (ATBA), with navigation only restricted where Safety Zones are active (see section 17).

Figure 6.1 Proposed Development Array Area Coordinates

Table 6.1 Coordinates for the Proposed Development Array Area

6.1.1.1      Refinement of the Proposed Development Array Area

The Proposed Development array area has been refined from that considered in the Scoping Report for the 2020 Berwick Bank (RPS Energy, 2020), the 2021 Scoping Report (RPS Energy (2021) and at the time of the first Hazard Workshop in September 2021. These refinements are presented in Figure 6.2   Open ▸ .

Figure 6.2 Refinement of the Proposed Development Array Area

Following the Scoping Report for the 2020 Berwick Bank, the more pointed south-eastern corner was softened, primarily due to concerns raised by shipping and navigation stakeholders. Additionally, the north-western section of the Proposed Development array area – part of the original proposed Marr Bank Wind Farm development, which was combined with the 2020 Berwick Bank to form the current Berwick Bank Wind Farm – was amended to create a gap between the Proposed Development array area and Seagreen and increase the width of the gap between the Proposed Development array area and Inch Cape. This version of the Proposed Development array area was presented at the first Hazard Workshop.

Following the Scoping Report and the first Hazard Workshop, the north-western section of the Proposed Development array area was again amended to increase the width of the gap between the Proposed Development array area and Seagreen and the Proposed Development array area and Inch Cape. The south-western and south-eastern sections of the Proposed Development array area were also refined further. This version of the Proposed Development array area was presented at the second Hazard Workshop and is considered throughout this NRA.

The Proposed Development array area represents a 23% reduction in extent from that considered in the Scoping Report and a 30% reduction in extent from that considered in the Scoping Report for the 2020 Berwick Bank (when considering the Berwick Bank and Marr Bank developments combined).

6.1.2        Proposed Development Export Cable Corridor

The Proposed Development export cable corridor runs between the southern boundary of the Proposed Development array area and the landfall point at Skateraw. The total area is approximately 49 nm2 (168 km2) with water depths within the Proposed Development export cable corridor ranging between 3 and 64 m below CD.

The offshore export cables will be located fully within the Proposed Development export cable corridor. The key coordinates defining the boundary of the Proposed Development export cable corridor are illustrated in Figure 6.3   Open ▸ and provided in Table 6.2   Open ▸ .

Figure 6.3 Proposed Development Export Cable Corridor Key Coordinates

The Proposed Development export cable corridor has also been refined from that considered in the first Hazard Workshop, with a second landfall location at Thorntonloch removed. A secondary export cable option to Blyth (the Cambois connection) is also under consideration and is considered as part of the cumulative risk assessment (see section 14.1.3).

Table 6.2 Key Coordinates for the Proposed Development Export Cable Corridor

6.2       Surface Infrastructure

6.2 Surface Infrastructure

6.2.1        Indicative Array Layout

Up to 317 surface structures will be installed within the Proposed Development array area, consisting of up to 307 wind turbines and 10 offshore substation platforms. The final positions of surface structures have not yet been defined, but for the purposes of the NRA an indicative worst case array layout has been determined and is presented in Figure 6.4   Open ▸ .

Figure 6.4 Overview of Indicative Worst Case Array Layout for Shipping and Navigation

The indicative worst case array layout consists of a full build out of the Proposed Development array area to maximise the spatial extent of vessel deviations and the maximum possible number of surface structures to maximise exposure for passing (or adrift) vessels.

The minimum spacing within the PDE is 1,000 m, however with the indicative layout relevant for shipping and navigation this spacing varies as follows. The indicative array layout includes at least two lines of orientation[3] for wind turbines with a minimum spacing between wind turbines (measured centre-to-centre) of 1,265 m. The minimum spacing within the PDE is 1,000 m, with this spacing considered within the risk assessment where appropriate. The offshore substation platforms are evenly spaced between the wind turbine rows, giving an overall minimum spacing between structures for the indicative array layout (measured centre-to-centre) of 1,265 m, in the northeast-southwest direction. The minimum spacing between structures in a northwest-southeast orientation is 1,780 m.

6.2.2        Wind Turbines

The wind turbines within the indicative array layout each have a maximum rotor diameter of 222 m and maximum blade tip height (above LAT) of between 257 and 267 m. However, the maximum design scenario values for shipping and navigation are associated with the largest possible wind turbines (which would not be used for the indicative array layout). These are 310 m for rotor diameter and between 307 and 355 m for maximum blade tip height.

Piled jackets and suction caisson jackets foundations have been considered as the maximum design scenario for shipping and navigation as these foundation types provide the maximum structure dimension at the sea surface, and therefore maximise exposure for passing (or adrift) vessels. The maximum design scenario for the wind turbines, which assume use of a piled jacket or suction caisson jacket foundation design, are provided in Table 6.3   Open ▸ .

Table 6.3 Wind Turbines Maximum Design Scenario for Shipping and Navigation

Floating foundations are not included in the PDE. Further descriptions of the foundation types under consideration are provided in volume 2, chapter 3.

6.2.3        Offshore Substation Platforms

The offshore substation platforms will be installed on piled jackets or suction caisson jacket foundations, with two types of substation under consideration – High Voltage Alternating Current (HVAC) and High Voltage Direct Current (HVDC). For HVAC offshore substation platforms the maximum topside dimensions are 39×39 m and for HVDC offshore substation platforms are 100×85 m.

6.3       Subsea Infrastructure

6.3 Subsea Infrastructure

Three types of subsea cables will be installed: inter-array cables, interconnector cables and offshore export cables. Each category of subsea cables is summarised in the following subsections.

6.3.1        Inter-Array Cables

The inter-array cables will be fully installed within the Proposed Development array area to connect individual wind turbines to each other and to the offshore substation platforms. Up to 661 nm (1,225 km) of inter-array cables will be required with up to 78 crossings, although the final length and number of crossings will depend upon the final array layout. The maximum height of inter-array cable crossings will be 3.5 m.

6.3.2        Interconnector Cables

The interconnector cables will be fully installed within the Proposed Development array area to provide interlink connections between the offshore substation platforms. Up to 46 nm (85 km) of interconnector cables will be required, although the final length will depend upon the final array layout.

6.3.3        Offshore Export Cables

The offshore export cables will be installed within the Proposed Development export cable corridor to carry the electricity generated by the wind turbines to the landfall location (Skateraw). Up to eight offshore export cables and 471 nm (872 km) of offshore export cables will be required with up to 16 crossings. The maximum height of offshore export cables crossings will be 3.5 m.

6.3.4        Cable Burial and Protection

Where available, the primary means of cable protection will be by seabed burial. The extent and method by which the subsea cables will be buried will depend on the results of a detailed seabed survey of the final subsea cable routes and associated cable burial risk assessment. However, a minimum burial depth of 0.5 m for all subsea cables associated with the Proposed Development is assumed as part of the maximum design scenario.

Where cable burial is not possible, alternative cable protection methods may be deployed which will be determined within the cable burial risk assessment. These methods may include a combination of rock installation, concrete mattresses, rock bags, cast iron shells, sleeving and Cable Protection Systems (CPS). It is assumed that up to 15% of all subsea cables may require cable protection as part of the maximum design scenario with a maximum cable protection height of 3 m and width of 20 m (excluding crossings).

6.4       Timescales

6.4 Timescales

6.4.1        Construction Phase

The offshore construction phase will indicatively commence in December 2025, last for up to eight years, and be undertaken in up to three phases.

6.4.2        Operation and Maintenance Phase

The operation and maintenance phase will last for up to 35 years.

6.4.3        Decommissioning Phase

The decommissioning phase will generally be the reverse of the construction phase in terms of duration, vessel types and vessel numbers. It is anticipated that all sea surface structures will be completely removed above the seabed and all subsea cables will be left in situ (although best practice will be followed at the time of decommissioning).

6.5       Vessel and Helicopter Numbers

6.5 Vessel and Helicopter Numbers

This subsection provides an overview of maximum vessel numbers for each activity and phase of the Proposed Development. Details relating to the routes to be undertaken by vessels associated with the Proposed Development are not available at this stage but will be defined as part of marine coordination (see section 6.5.2). Return trips may not occur uniformly throughout each phase depending on factors such as relevant activities and crew transfer times.

6.5.1        Construction Phase

Up to 10,964 return trips by construction vessels (excluding site preparation activities) may be made throughout the construction phase. The maximum number of vessel types associated with construction phase activities are summarised in Table 6.4   Open ▸ .

Table 6.4 Maximum Vessel Numbers per Vessel Type for Construction Phase

Additionally, up to 3,214 return trips by up to 13 helicopters may be made during the construction phase.

6.5.2        Operation and Maintenance Phase

Up to 2,323 return trips per year by operation and maintenance vessels may be made throughout the operation and maintenance phase.[4] The maximum number of vessel types associated with the operation and maintenance phase are summarised in Table 6.5   Open ▸ .

Table 6.5 Maximum Vessel Numbers per Vessel Type for Operation and Maintenance Phase

During both the construction and operation and maintenance phases, logistics will be managed by a marine coordination team. An integrated Health, Safety and Environment (HSE) management system will be in place to ensure control of all vessels and their respective works. The Project will be operational 24/7.

6.5.3        Decommissioning Phase

As noted in section 6.4.3, the decommissioning phase will generally be the reverse of the construction phase including in terms of vessel types and vessel numbers.

6.6       Maximum Design Scenario

6.6 Maximum Design Scenario

The maximum design scenario for each shipping and navigation hazard is provided in Table 6.6   Open ▸ and is based on the parameters described in the previous subsections.

Table 6.6 Maximum Design Scenario by Hazard for Shipping and Navigation

7       Navigational Features

7 Navigational Features

A plot of navigational features in proximity to the Proposed Development array area and export cable corridor is presented in Figure 7.1   Open ▸ . Each of the features shown is discussed in the following subsections and has been identified using the most detailed UKHO Admiralty Charts available.

Figure 7.1 General Overview of Navigational Features in Proximity to the Proposed Development

7.1       Other Offshore Wind Farm Developments

7.1 Other Offshore Wind Farm Developments

A plot of nearby other offshore wind farm developments in proximity to the Proposed Development is presented in Figure 7.2   Open ▸ , colour-coded by development status.

Figure 7.2 Offshore Wind Farm Developments in Proximity to the Proposed Development

The closest offshore wind farm developments to the Proposed Development array area are Seagreen Offshore Wind Farm (hereafter referred to as ‘Seagreen’) located approximately 2.7 nm to the north, and Inch Cape Offshore Wind Farm (hereafter referred to as ‘Inch Cape’) located approximately 4.1 nm to the west. It is noted that these distances are measured between the consented boundaries of the respective developments[5].

Seagreen is under construction with the construction buoyage deployed in September 2021 and the development expected to be fully commissioned in November 2023 (Seagreen Wind Energy Ltd., 2020). A variation to development parameters for Inch Cape was consented in June 2019, with CfD secured in July 2022 (Department for Business, Energy and Industrial Strategy (BEIS), 2022).

NnG is also located in the region, approximately 8.8 nm to the west of the Proposed Development array area. NnG is under construction with the construction buoyage deployed in May 2020 and the development expected to be fully commissioned in November 2022 (EDF, 2020).

Other offshore wind farm developments in the region include Kincardine (operational), European Offshore Wind Deployment Centre (EOWDC) (operational), Forthwind (scoped) and ScotWind sites Cluaran Deas Ear, Morven, Bellrock, Campion, Mara Mhor, and Ossian (all areas of search). Further details are included in section 14.1.

7.2       Ports and Related Services

7.2 Ports and Related Services

A plot of nearby ports and harbours is presented in Figure 7.3   Open ▸ . It is noted that there are other ports and harbours within the Firth of Forth not labelled in Figure 7.3   Open ▸ , but for clarity only the more prominent ports and harbours are shown. Ports and harbours within the Firth of Forth are considered collectively throughout the NRA.

Figure 7.3 Ports and Harbours in Proximity to the Proposed Development

The closest port or harbour to the Proposed Development array area is Arbroath Harbour, located approximately 23 nm to the north-west, on the Angus coast. The Admiralty Sailing Directions describe Arbroath as “mainly a fishing port used by small and medium-sized fishing vessels” which is also occupied by a yacht marina (UKHO, 2021).

Montrose Port is located approximately 24 nm to the north-west on the Angus coast and is described by the Admiralty Sailing Directions as “a commercial port and a supply base for the offshore oil industry” (UKHO, 2021).

7.2.1        Ports and Harbours within the Firth of Forth

The Firth of Forth contains many ports and harbours of varying sizes, including:

• Aberdour;
• Anstruther;
• Braefoot Bay;
• Burntisland;
• Cockenzie;
• Crail;
• Grangemouth;
• Granton;
• Leith;
• Methil;
• North Berwick;
• North Queensferry;
• Pettycur Pier;
• Pittenweem;
• Rosyth; and
• St. Monans.

Grangemouth is “the largest port in Scotland” and handles “all types of vessels, including container vessels, tankers and LPG carriers” (UKHO, 2021). Rosyth, Leith and Braefoot Bay are also prominent ports which handle a range of vessel types.

A VTS – the Forth and Tay Navigation Service – is operated from Grangemouth with “all vessels of 50 GT and over required to report on passing the eastern limit and at all subsequent reporting points” (UKHO, 2021). Forth Ports have confirmed during consultation that the VTS does not extend as far out as the Firth of Forth offshore wind farm developments, including the Proposed Development array area. Forth Ports do not advise vessel traffic as far offshore as the Proposed Development array area.

7.2.2        Vessel Arrivals

The number of vessel arrivals at ports in the region, as reported by the Department for Transport (DfT), is presented in Figure 7.4   Open ▸ . These statistics exclude some vessel movements which occur within port or harbour limits, but nevertheless give a clear indication of the relative traffic levels and trends.

Figure 7.4 Vessel Arrivals to Commercial Ports in Proximity to the Proposed Development

As a collective, ports in the Forth are the most frequented commercial ports in the area followed by Aberdeen, although both ports have experienced a slight downward trend in vessel arrivals in recent years. In the case of Aberdeen, this may be partially related to the effects of COVID-19 pandemic.

7.3       Aids to Navigation

7.3 Aids to Navigation

A plot of nearby aids to navigation is presented in Figure 7.5   Open ▸ . The information provided in Figure 7.5   Open ▸ and the following text is current as of August 2022.

Figure 7.5 Aids to Navigation in Proximity to the Proposed Development

There are no aids to navigation located within the Proposed Development array area – there are, however, scientific buoys and Light Detection and Ranging (Lidar) equipment present to gauge readings.

There is one aid to navigation located within the Proposed Development export cable corridor, a special mark situated in the approaches to Torness Power Station at the Skateraw landfall location.

There is a group of nine aids to navigation located west of the Proposed Development array area. These form the construction buoyage for NnG, and were deployed in May 2020, as confirmed by NLB during consultation. They are expected to be removed following the commissioning of the development, anticipated in November 2022 (EDF, 2020). Similarly, there is a group of 13 aids to navigation north of the Proposed Development array area that form the construction buoyage for Seagreen that were deployed in September 2021 and expected to be removed in September 2023 post-commissioning of the development.

The Inch Cape Met Mast and Bell Rock Lighthouse, both located west of the Proposed Development array area, also serve as aids to navigation.

7.4       Anchorage Locations

7.4 Anchorage Locations

The majority of anchorage locations in the region are located within the Firth of Forth, where there are numerous designated anchorages and small vessel anchorages. Outside the Forth, there are designated anchorage points in close proximity to various coastal ports and harbours including off Dunbar, between St. Abbs and Eyemouth, off St. Andrews and in Lunan Bay to the south of Montrose.

The closest anchorage location to the Proposed Development array area is the designated anchorage point between St. Abbs and Eyemouth located approximately 19 nm to the south-west. The closest anchorage location to the Proposed Development export cable corridor is the designated anchorage off Dunbar located approximately 3.5 nm to the west of the Skateraw landfall location.

7.5       Military Practice and Exercise Areas

7.5 Military Practice and Exercise Areas

Military Practice and Exercise Areas (PEXA) close to the Proposed Development array area are presented in Figure 7.6   Open ▸ .

Figure 7.6 MoD Practice Areas in Proximity to the Proposed Development (Marine Scotland, 2019)

There are two MoD naval PEXAs located within the Outer Firth of Forth (X5641 and X5642), with area X5642 overlapping the Proposed Development array area. There is also a firing practice area off the Northumberland coast (Druridge Bay) located approximately 19 nm to the south of the Proposed Development array area, covering an area of approximately 2,300 nm2.

In addition, there is a smaller firing range (Barry Buddo) located approximately 24 nm to the west of the Proposed Development array area, at the mouth of the River Tay.

No restrictions are placed on the right to transit a military PEXA at any time, although mariners are advised to exercise caution. Exercises and firing only occur when the area is considered to be clear of all shipping.

There are not anticipated to be any hazards to shipping and navigation users associated with military PEXAs, although military vessels are considered as part of the baseline characterisation of vessel traffic movements in section 10.

7.6       Charted Wrecks

7.6 Charted Wrecks

A plot of charted wrecks is presented in Figure 7.7   Open ▸ . Charted wrecks are those detailed on UKHO Admiralty Charts and are considered to pose a risk to surface navigation or subsea operations. Further details relating to wrecks are provided in volume 4, appendix 22 and the Marine Archaeology Technical Report which accompanies the Application.

Figure 7.7 Wrecks and Obstructions in Proximity to the Proposed Development

There are 10 charted wrecks located within the Proposed Development array area, with the shallowest at 35 m below CD, in the north-west of the Proposed Development array area. There are three charted wrecks located within the Proposed Development export cable corridor, all in the nearshore area.

7.7       Other Features

7.7 Other Features

7.7.1        International Maritime Organization Routeing Measures

There are no IMO routeing measures in the region.

7.7.2        Oil and Gas Infrastructure

There is no surface oil and gas infrastructure in the region, with the closest surface infrastructure the BW Catcher Floating Production Storage and Offloading (FPSO) at the Catcher Area Development, located approximately 73 nm to the east of the Proposed Development array area.

There are some wellheads located in the region, with the closest an abandoned well located approximately 5.9 nm to the north of the Proposed Development array area. All other wells in the region are also abandoned.

7.7.3        Marine Aggregate Dredging Areas

There are no marine aggregate dredging areas in the region, noting that there are no marine aggregate dredging areas currently licensed in Scotland.

7.7.4        Spoil Grounds

There are two areas of spoil ground located approximately 20 nm west of the Proposed Development array area in the approaches to the Firth of Tay. There is also an area of spoil ground located approximately 1.5 nm from the Proposed Development export cable corridor, close to the Skateraw landfall location.

7.7.5        Ammunition Disposal Grounds

There are two ammunition disposal grounds (disused) located approximately 11 nm west of the Proposed Development array area immediately east of the Isle of May.

7.7.6        Submarine Cables and Pipelines

There are no existing submarine cables or pipelines in the region. The export cable associated with NnG is currently being installed and runs between the south-west of the Proposed Development array area and Thorntonloch, on the East Lothian coast. Likewise, the export cable associated with Seagreen is currently being installed and runs between the west of the Proposed Development array area and Carnoustie, on the Angus coast.

7.7.7        Marine Environment High Risk Areas

There is a Marine Environment High Risk Areas (MEHRA) for the Isle of May, located approximately 21 nm west of the Proposed Development at the entrance to the Firth of Forth. MEHRAs are areas along the UK coast designed to “inform [ships’] Masters of areas where there is a real prospect of a problem arising. This prime purpose stands alone and regardless of any consequential defensive measures” (Lord Donaldson, 1994).

8       Meteorological Ocean Data

8 Meteorological Ocean Data

This section presents meteorological and oceanographic statistics local to the Proposed Development. The data presented in this section had been used as input to the collision and allision risk modelling (see section 16).

8.1       Wind

8.1 Wind

Based on wind direction data modelled by Vortex at a nearby location and at 10 m height, the proportion of the wind direction within each 30-degree interval is presented in Figure 8.1   Open ▸ in the form of a wind rose. It can be seen that winds are predominantly from the west to the south.

Figure 8.1 Wind Direction Distribution for Proposed Development

8.2       Wave

8.2 Wave

Based on significant wave height data recorded by Fugro between December 2010 and May 2012 at a location within the Proposed Development array area, the proportion of the sea state within each of three defined ranges, where the sea state is based upon significant wave height, is presented in Table 8.1   Open ▸ . It should be noted that the percentages presented are rounded to one decimal place.

Table 8.1 Sea State Distribution for Proposed Development

8.3       Visibility

8.3 Visibility

Based on information provided in the Admiralty Sailing Directions (UKHO, 2021), the proportion of poor visibility (defined as the proportion of a year where the visibility can be expected to be less than 1 km) is 3%.

8.4       Tide

8.4 Tide

From UKHO Admiralty Chart 1407, currents within and in proximity to the Proposed Development are set in a generally north to south direction on the flood tide and north to south direction on the ebb tide. The greatest peak flood tidal rate is 1.4 knots (kt) and the greatest peak ebb tidal rate is also 1.4 kt. The peak speed and corresponding direction data for the flood and ebb tides for the relevant tidal diamonds on UKHO Admiralty Chart 1407 are presented in Table 8.2   Open ▸

Table 8.2 Peak Flood and Ebb Tidal Data in Proximity to Proposed Development

Based upon the available data, no hazards are expected at high water that would not also be expected at low water, and vice versa. The wind farm structures are not expected to result in any additional risk on the existing tidal streams in relation to their effect on existing shipping and navigation users.

9       Emergency Response

9 Emergency Response

This section summarises the existing Search and Rescue (SAR) resources in the region, and issues being considered in relation to the Proposed Development.

9.1       Search and Rescue Helicopters

9.1 Search and Rescue Helicopters

In July 2022, the Bristow Group were awarded a new 10-year contract by the MCA (as an executive agency of the DfT) beginning in September 2024 to provide helicopter SAR operations in the UK. Bristow have been operating the service since April 2015.

The SAR helicopter service is currently operated out of 10 base locations around the UK, with the closest to the Proposed Development located at Inverness Airport, approximately 94 nm to the north-west. This base operates two AgustaWestland 189 (AW189) helicopters. As part of the new MCA contract, Bristow will also launch two new seasonal bases in Fort William and Carlisle, with the latter likely to be relevant to the Proposed Development.

Of particular note to the Proposed Development array area and export cable corridor is the Prestwick SAR helicopter base 100 nm west of the Proposed Development array area, from which all SAR helicopter taskings in the Proposed Development export cable corridor departed from (see section 9.1.2).

The DfT has produced data on civilian SAR helicopter activity in the UK by the Bristow Group on behalf of the MCA between April 2015 and March 2021.

9.1.1        Proposed Development Array Area

The locations of SAR helicopter taskings within the Proposed Development array area shipping and navigation study area is presented in Figure 9.1   Open ▸ , colour-coded by tasking type.

Figure 9.1 DfT SAR Helicopter Taskings Data within Proposed Development Array Area Shipping and Navigation Study Area by Type (2015 to 2021)

There were two unique SAR incidents in the Proposed Development array area shipping and navigation study area between April 2015 and March 2021. Both taskings originated from the Inverness base with one involving a rescue/recovery and one involving a search only. The rescue/recovery tasking was supported and completed. The search-only tasking was complete with no casualties found. No SAR incidents were recorded within the Proposed Development array area itself.

9.1.2        Proposed Development Export Cable Corridor

The locations of SAR helicopter taskings within the Proposed Development export cable corridor shipping and navigation study area is presented in Figure 9.2   Open ▸ , colour-coded by tasking type.

Figure 9.2 DfT SAR Helicopter Taskings Data within Proposed Development Export Cable Corridor Shipping and Navigation Study Area by Type (2015 to 2021)

There were six SAR incidents in the Proposed Development export cable corridor shipping and navigation study area between April 2015 and March 2021. All six taskings originated from the Prestwick base. Only one incident was maritime, with three being coastal, and the other two being land-based. The maritime tasking involved a rescue/recovery and was terminated on scene.

9.2       Royal National Lifeboat Institution

9.2 Royal National Lifeboat Institution

The RNLI is organised into six divisions, with the relevant region for the Proposed Development being ‘Scotland’. Based out of more than 230 stations around the UK, there are over 400 active lifeboats across the RNLI fleet, including both all-weather lifeboats (ALB) and inshore lifeboats (ILB). RNLI lifeboats are available on a 24-hour basis throughout the year.

The closest RNLI station to the Proposed Development array area is at Eyemouth, located approximately 19 nm to the south-west, where both an ALB and ILB are in use. It is noted that the RNLI have a strategic performance standard of reaching casualties up to a maximum of 100 nm offshore.

As noted in section 9.2, the RNLI have a strategic performance standard of reaching casualties up to a maximum of 100 nm offshore.

The locations of incidents responded to by the RNLI within the Proposed Development array area shipping and navigation and export cable corridor study areas between 2010 and 2019 are presented in Figure 9.3   Open ▸ , colour-coded by incident type. The same data is presented in Figure 9.4   Open ▸ , colour-coded by casualty type. It is noted that hoaxes and false alarms have been excluded from the analysis.

Figure 9.3 RNLI Incident Data within Proposed Development Array Area Shipping and Navigation and Export Cable Corridor Study Areas by Incident Type (2010 to 2019)

Figure 9.4 RNLI Incident Data within Proposed Development Array Area Shipping and Navigation and Export Cable Corridor Study Areas by Casualty Type (2010 to 2019)

A total of 14 RNLI lifeboat launches to 11 unique incidents were reported within the Proposed Development array area shipping and navigation study area, corresponding to an average of one unique incident per year. Incidents were primarily located inshore of the Proposed Development array area.

Of the 14 unique incidents in the Proposed Development array area shipping and navigation study area, the most frequently recorded incident types were flooding/foundering and vessel may be in trouble (27% each). The other incident types recorded were machinery failure (18%), other (9%), person in danger (9%), and steering failure (9%).

Of the 14 unique vessels related to the recorded incidents in the Proposed Development array area shipping and navigation study area, the most frequently recorded casualties were recreational sailing vessels (45%) and fishing vessels (36%).

There was one incident recorded within the Proposed Development array area itself, involving an ‘other recreational’ vessel which may be in trouble.

The most common base stations recorded for lifeboat launches for incidents in the Proposed Development array area shipping and navigation study area was Eyemouth (45%) followed by Dunbar (18%) and Montrose (18%). Lifeboat launches were also reported out of the stations at Arbroath and Stonehaven.

A total of 65 RNLI lifeboat launches to 48 unique incidents were reported within the Proposed Development export cable corridor shipping and navigation study area, corresponding to an average of approximately five unique incidents per year. Incidents were primarily located close to the shoreline.

Of the 48 unique incidents in the Proposed Development export cable corridor shipping and navigation study area, the most frequently recorded incident types were machinery failure (36%) and person in danger (20%). Other recorded incident types included vessel may be in trouble (18%), collision (4%), steering failure (4%), capsize (2%), and flooding/foundering (2%). Incidents classed as ‘other’ comprised 13% of all unique incidents in the Proposed Development export cable corridor shipping and navigation study area. Incidents where the type was unspecified were not included in this analysis.

Of the 48 unique incidents in the Proposed Development export cable corridor shipping and navigation study area, recorded casualty types included fishing vessels (25%), powered recreational vessels (21%), person in danger (17%), personal craft (17%), sailing recreational vessels (10%), other recreational vessels (6%), other (non-vessel based) (2%), and other (vessel based) (2%).

There were nine incidents recorded within the Proposed Development export cable corridor itself, corresponding to approximately one incident per year. Of these incidents, the most frequently recorded incident types were machinery failure and vessel may be in trouble (22% each). Incidents where the type was unspecified were not included in this analysis. The most frequently recorded casualty types were personal craft (33%), fishing vessels (22%), and powered recreational vessels (22%).

The base station recorded for lifeboat launches for incidents in the Proposed Development export cable corridor shipping and navigation study area was Dunbar.

9.3       Maritime Rescue Coordination Centres and Joint Rescue Coordination Centres

9.3 Maritime Rescue Coordination Centres and Joint Rescue Coordination Centres

Her Majesty’s Coastguard (HMCG), a division of the MCA, is responsible for requesting and tasking SAR resources made available to other authorities and for coordinating the subsequent SAR operations (unless they fall within military jurisdiction).

The HMCG coordinates SAR operations through a network of 11 Maritime Rescue Coordination Centres (MRCC), including a Joint Rescue Coordination Centre (JRCC) based in Hampshire.

All of the MCA’s operations, including SAR, are divided into three geographical regions. The ‘Scotland’ region covers the area encompassing the Proposed Development.

Each region is divided into six districts with its own MRCC, which coordinates the SAR response for maritime and coastal emergencies within its own district boundaries. The closest MRCC to the Proposed Development is at Aberdeen, located approximately 40 nm north of the Proposed Development array area.

9.4       Global Maritime Distress and Safety System

9.4 Global Maritime Distress and Safety System

The Global Maritime Distress and Safety System (GMDSS) is a maritime communications system used for emergency and distress messages, vessel to vessel routeing communications and vessel to shore routine communications. It is implemented globally and vessels engaged in international voyages are obliged to carry GMDSS certified communication equipment.

There are four GMDSS sea areas, and in the UK, it is the responsibility of the MCA to ensure Very High Frequency (VHF) coverage from coastal stations within sea area A1. the Proposed Development is located within an A1 sea area, as shown in Figure 9.5   Open ▸ , and therefore in the event of an emergency any vessel located in proximity to the Proposed Development would be able to contact HMCG via VHF.

Figure 9.5 GMDSS Sea Areas (MCA, 2021)

9.5       Marine Accident Investigation Branch

9.5 Marine Accident Investigation Branch

All UK flagged vessels and non-UK flagged vessels in UK territorial waters (12 nm), a UK port, or carrying passengers to a UK port are required to report incidents to the MAIB.

The locations of accidents, injuries and hazardous incidents reported to the MAIB within the Proposed Development array area shipping and navigation and export cable corridor study areas between 2010 and 2019 are presented in Figure 9.6   Open ▸ , colour-coded by incident type. The same data is presented in Figure 9.7   Open ▸ , colour-coded by vessel type.

Figure 9.6 MAIB Incident Data within Proposed Development Array Area Shipping and Navigation and Export Cable Corridor Study Areas by Incident Type (2010 to 2019)

Figure 9.7 MAIB Incident Data within Proposed Development Array Area Shipping and Navigation and Export Cable Corridor Study Areas by Vessel Type (2010 to 2019)

A total of three unique incidents were reported to the MAIB within the Proposed Development array area shipping and navigation study area, corresponding to an average of approximately one incident every three years. Two of these incidents occurred inshore of the Proposed Development array area with the other occurring north of the Proposed Development array area. No incidents were reported to the MAIB within or offshore of the Proposed Development array area, with the closest reported approximately 5 nm west of the Proposed Development array area.

Of the three incidents, there was one instance each of machinery failure, loss of control, and accident to person. All three incidents involved a fishing vessel. None of the incidents required the incident vessel to be towed or salvaged. There was one injury recorded, but no fatalities occurred.

A review of older MAIB incident data within the Proposed Development array area shipping and navigation study area between 2000 and 2009 indicates that the number of incidents has decreased over time, with four unique incidents recorded in the ten-year period, corresponding to an average of one incident every two to three years. Of the recorded incidents, all four incident types were machinery failure. Three of the vessels involved were fish catching/processing, with the other being a tanker.

A total of 14 unique incidents were reported to the MAIB within the Proposed Development export cable corridor shipping and navigation study area, corresponding to an average of approximately one to two incidents every year. Two of these incidents involved two vessels, resulting in a total of 16 vessels involved in incidents. Incidents were primarily located close to the shoreline.

Of the 14 unique incidents in the Proposed Development export cable corridor shipping and navigation study area, the most frequently recorded incident type was machinery failure (79%). The other two incident types recorded were hazardous incidents (14%) and flooding/foundering (7%).

Of the 16 vessels involved in the incidents in the Proposed Development export cable corridor shipping and navigation study area, the most frequently recorded vessel type was fishing vessels (81%).

There were four incidents recorded within the Proposed Development export cable corridor itself, all of which occurred close to the shoreline. Three of these incidents related to machinery failure for a fishing vessel with the other related to a hazardous incident between a tanker and a fishing vessel. None of the incidents required the incident vessel to be towed or salvaged. There were no injuries or fatalities noted for any of the recorded incidents.

A review of older MAIB incident data within the Proposed Development export cable corridor shipping and navigation study area between 2000 and 2009 indicates that the number of incidents has also decreased over time, with 18 unique incidents recorded in the ten-year period, corresponding to an average of just under two incidents every year. There were two instances of hazardous incidents between two vessels – one between a dry cargo vessel and fish catching/processing vessel, and another between a passenger cargo vessel and fish catching/processing vessel. Of the total recorded incidents in the Proposed Development export cable corridor, incident types were primarily machinery failure (72%), with hazardous incidents (22%) and accident to person (6%) also noted. Vessel types primarily involved included fish catching/processing (70%) and dry cargo (10%).

9.6       Historical Offshore Wind Farm Incidents

9.6 Historical Offshore Wind Farm Incidents

As of August 2022, there are 41 fully commissioned and generating offshore wind farms in the UK, ranging from the North Hoyle Offshore Wind Farm (fully commissioned in 2003) to Triton Knoll Offshore Wind Farm (fully commissioned in 2022). These developments consist of approximately 18,850 fully operational wind turbine years.

9.6.1        Incidents Involving UK Offshore Wind Farm Developments

MAIB incident data has been used to collate a list of historical collision and allision incidents involving UK offshore wind farm developments, which are summarised in Table 9.1   Open ▸ . Other sources have also been used to produce this list including the UK Confidential Human Factors Incident Reporting Programme (CHIRP) for Aviation and Maritime, International Marine Contractors Association (IMCA) and basic web searches. This list is limited to collision and allision incidents given their specific relevance to shipping and navigation. Only incidents that have been formally reported are captured.

The worst consequences reported for vessels involved in a collision or allision incident involving a UK offshore wind farm development have been related to minor flooding, with no life-threatening injuries to persons reported.

As of August 2022, there have been no collisions as a result of the presence of an offshore wind farm in the UK. The only reported collision incident in relation to a UK offshore wind farm involved a project vessel hitting a third-party vessel whilst in harbour.

As of August 2022, there have been 13 reported[6] cases of an allision between a vessel and a wind turbine (under construction, operational or disused) in the UK, with all but two involving a support vessel for the development and the errant vessel in each case under power rather than drifting. Therefore, there has been an average of 1,570 years of wind turbine operation per wind turbine allision incident in the UK. This is a conservative calculation given that only operational wind turbine years have been included (whereas allision incidents counted include non-operational wind turbines).

Table 9.1 Summary of Historical Collision and Allision Incidents Involving UK Offshore Wind Farm Developments

9.6.2        Incidents Involving Non-UK Offshore Wind Farms

It is acknowledged that collision and allision incidents involving non-UK offshore wind farm developments have also occurred. However, it is not possible to maintain a comprehensive list of such incidents.

One high profile non-UK incident which is noted is that involving a bulk carrier in January 2022 which dragged anchor during a storm in Dutch waters and collided with another anchored vessel. The vessel began to take on water, leading to all crew members being evacuated by helicopter. The vessel then continued to drift towards shore including though an under construction offshore wind farm where it allided with a WTG foundation and a platform foundation before being taken under tow.

9.6.3        Incidents Responded to by Vessels Associated with UK Offshore Wind Farm Developments

A list has been collated from news reports, basic web searches and experience of working with existing offshore wind farm developments, of historical incidents responded to by vessels associated with UK offshore wind farm developments. This list is summarised in Table 9.2   Open ▸ . It is noted that the initial causes of these incidents were not related to the associated offshore wind farms.

Table 9.2   Open ▸ comprises known incidents that were responded to by a wind farm vessel. Additional incidents associated with wind farms themselves are also known to have occurred. These incidents typically involve an accident to person which requires medical attention (including emergency response) but does not affect the operation of the vessel involved.

Table 9.2 Historical Incidents Responded to by Vessels Associated with UK Offshore Wind Farm Developments

10 Vessel Traffic Movements

10 Vessel Traffic Movements

This section presents an analysis of vessel traffic movements in relation to the Proposed Development array area and export cable corridor. The methodology for vessel traffic data collection, including details of the on-site vessel traffic surveys, is provided in section 5.2.

10.1   Proposed Development Array Area

10.1 Proposed Development Array Area

A number of vessel tracks recorded during the Proposed Development array area survey periods were classified as temporary (non-routine), such as the tracks of the survey vessel, other non-routeing survey vessels and vessels associated with the construction of NnG and Seagreen. These have therefore been excluded from the analysis.

A plot of the vessel tracks recorded during a 14-day survey period in August 2022, colour-coded by vessel type and excluding temporary traffic, is presented in Figure 10.1   Open ▸ . A plot of the vessel tracks recorded during a further 14-day survey period in January 2021, colour-coded by vessel type and excluding temporary traffic, is presented in Figure 10.2   Open ▸ .

Figure 10.1 Vessel Traffic Movements within Proposed Development Array Area Shipping and Navigation Study Area by Vessel Type (14 Days Summer 2022)

Figure 10.2 Vessel Traffic Movements within Proposed Development Array Area Shipping and Navigation Study Area by Vessel Type (14 Days Winter 2021)

Plots of the vessel tracks for the summer and winter survey periods converted to a density heat map are presented in Figure 10.3   Open ▸ and Figure 10.4   Open ▸ , respectively. It can be seen that, during the summer period there is negligible vessel density where the Proposed Development array area overlaps Seagreen. In contrast, during the winter period (which predates the start of Seagreen construction) some vessel density was observed where the Proposed Development array area overlaps Seagreen.

Figure 10.3 Vessel Density Heat Map within Proposed Development Array Area Shipping and Navigation Study Area (14 Days Summer 2022)

Figure 10.4 Vessel Density Heat Map within Proposed Development Array Area Shipping and Navigation Study Area (14 Days Winter 2021)

10.1.1    Vessel Counts

For the 14 days analysed in the summer survey period, there was an average of 14 unique vessels per day recorded within the Proposed Development array area shipping and navigation study area. In terms of vessels intersecting the Proposed Development array area itself, there was an average of three to four unique vessels per day.

The daily number of unique vessels recorded within the Proposed Development array area shipping and navigation study area and the Proposed Development array area itself during the summer survey period are presented in Figure 10.5   Open ▸ . Since the survey commenced and concluded midway through the first and last days of the summer survey period (as described in section 5.2), the first and last days are partial.

Figure 10.5 Unique Vessels per Day within the Proposed Development Array Area and Shipping and Navigation Study Area (14 Days Summer 2022)

Throughout the summer survey period, approximately 25% of unique vessel tracks recorded within the Proposed Development array area shipping and navigation study area intersected the Proposed Development array area itself.

The busiest day recorded within the Proposed Development array area shipping and navigation study area throughout the summer survey period was 12 August when 25 unique vessels were recorded. The busiest days recorded within the Proposed Development array area itself throughout the summer survey period was 11 August when eight unique vessels were recorded.

The quietest full days recorded within the Proposed Development array area shipping and navigation study area throughout the summer survey period were 7 August and 1 August when nine unique vessels were recorded each. The quietest full days recorded within the Proposed Development array area itself throughout the summer survey period were 7 August and 15 August when one unique vessel was recorded each.

For the 14 days analysed in the winter survey period, there was an average of 14 unique vessels per day recorded within the Proposed Development array area shipping and navigation study area. In terms of vessels intersecting the Proposed Development array area itself, there was an average of five unique vessels per day.

The daily number of unique vessels recorded within the Proposed Development array area shipping and navigation study area and the Proposed Development array area itself during the winter survey period are presented in Figure 10.6   Open ▸ .

Figure 10.6 Unique Vessels per Day within Proposed Development Array Area and Shipping and Navigation Study Area (14 Days Winter 2021)

Throughout the winter survey period approximately 36% of unique vessel tracks recorded within the Proposed Development array area shipping and navigation study area intersected the Proposed Development array area itself.

The busiest day recorded within the Proposed Development array area shipping and navigation study area throughout the winter survey period was 23 January when 24 unique vessels were recorded. The busiest day recorded within the Proposed Development array area itself throughout the winter survey period was also 23 January when nine unique vessels were recorded.

The quietest day recorded within the Proposed Development array area shipping and navigation study area throughout the winter survey period was 12 January when nine unique vessels were recorded. The quietist day recorded within the Proposed Development array area itself throughout the winter survey period was 17 January when one unique vessel was recorded.

10.1.2    Vessel Types

The percentage distribution of the main vessel types recorded within the Proposed Development array area shipping and navigation study area and the Proposed Development array area itself is presented in Figure 10.7   Open ▸ .

Figure 10.7 Vessel Type Distribution within Proposed Development Array Area and Shipping and Navigation Study Area (28 Days Summer 2022 and Winter 2021)

Throughout the summer period, the most common vessel types in the Proposed Development array area shipping and navigation study area were tankers (30%), cargo vessels (23%), and passenger vessels (12%). Throughout the winter period, the most common vessel types were cargo vessels (37%), tankers (32%), and fishing vessels (13%).

It is noted that no commercial ferries were identified in the winter vessel traffic survey data, which aligns with feedback provided by Forth Ports during consultation (see 10 June 2020 entry in Table 4.1   Open ▸ ).

10.1.2.1  Cargo Vessels

The tracks of cargo vessels recorded within the Proposed Development array area shipping and navigation study area throughout the summer 2022 survey period are presented in Figure 10.8   Open ▸ . Following this, the tracks of cargo vessels recorded within the Proposed Development array area shipping and navigation study area throughout the winter 2021 survey period are presented in Figure 10.9   Open ▸ .

Figure 10.8 Cargo Vessel Traffic within Proposed Development Array Area Shipping and Navigation Study Area (14 Days Summer 2022)

Figure 10.9 Cargo Vessel Traffic within Proposed Development Array Area Shipping and Navigation Study Area (14 Days Winter 2021)

Throughout the survey periods an average of four unique cargo vessels per day were recorded within the Proposed Development array area shipping and navigation study area. Regular cargo vessel routeing included north-south following the UK east coast, north-west-south-east out of Montrose and east-west out of the Firth of Forth. Cargo vessels avoided the Seagreen buoyed construction area during the summer period.

The majority of cargo vessels recorded within the Proposed Development array area shipping and navigation study area were general cargo (79%). Other subtypes included bulk carriers (10%) and containerships (8%).

10.1.2.2  Tankers

The tracks of tankers recorded within the Proposed Development array area shipping and navigation study area throughout the summer 2022 survey period are presented in Figure 10.10   Open ▸ . Following this, the tracks of tankers recorded within the Proposed Development array area shipping and navigation study area throughout the winter 2021 survey period are presented in Figure 10.11   Open ▸ .

Figure 10.10 Tanker Traffic within Proposed Development Array Area Shipping and Navigation Study Area (14 Days Summer 2022)

Figure 10.11 Tanker Traffic within Proposed Development Array Area Shipping and Navigation Study Area (14 Days Winter 2021)

Throughout the survey periods an average of four unique tankers per day were recorded within the Proposed Development array area shipping and navigation study area. Regular tanker routeing included east-west out of the Firth of Forth and north-south following the UK east coast. Tankers avoided the Seagreen buoyed construction area during the summer period.

Tanker subtypes recorded within the Proposed Development array area shipping and navigation study area included oil/chemical tankers (30%), oil products tankers (20%) and Liquid Petroleum Gas (LPG) tankers (18%).

10.1.2.3  Commercial Fishing Vessels

Vessel Traffic Survey Data

Commercial fishing vessel data was extracted from the vessel tracks recorded during the vessel traffic surveys. It is noted that the term ‘fishing vessel’ as used throughout this NRA refers to commercial fishing vessels, and any non-commercial fishing activity (such as rod and line angling) is categorised under recreational vessel activity. On this basis the tracks of commercial fishing vessels recorded within the Proposed Development array area shipping and navigation study area throughout both survey periods are presented in Figure 10.12   Open ▸ .

Figure 10.12 Commercial Fishing Vessel Traffic within Proposed Development Array Area Shipping and Navigation Study Area (28 Days Summer 2022 and Winter 2021)

Throughout the survey periods an average of one to two unique commercial fishing vessels per day passed within the Proposed Development array area shipping and navigation study area. Of the commercial fishing vessels recorded, 84% were recorded via AIS with 14% recorded via radar and 2% recoded via visual observations. Although AIS is only mandatory for commercial fishing vessels greater than 15 m LOA, 81% of the commercial fishing vessels recorded using AIS were under 15 m LOA.

Those commercial fishing vessels observed within the Seagreen buoyed construction area were recorded during the winter period, prior to the start of Seagreen construction.

Based on the average speed and behaviour of vessel tracks, there is a substantial volume of the fishing vessel activity in the Proposed Development array area shipping and navigation study area that is characteristic of active fishing rather than transits.

Fishing gear type could only be identified for 28% of the commercial fishing vessels recorded. The most common fishing gear types recorded in the Proposed Development array area shipping and navigation study area throughout the survey periods were potter/whelkers (62%) and demersal trawlers (15%).

Nationality could be identified for 87% of the commercial fishing vessels recorded, with the remaining 13% consisting of the commercial fishing vessels recorded via radar/visual observation. The nationality of all commercial fishing vessels able to be recorded was British.

Vessel Monitoring System Data

In addition to the vessel traffic survey data, Vessel Monitoring System (VMS) data recorded between July 2018 and June 2021 has also been analysed within the Proposed Development array area shipping and navigation study area (noting that this period predates the start of Seagreen construction – Seagreen is included in Figure 10.13   Open ▸ for context). A density grid, using the VMS data during this period as input, is presented in Figure 10.13   Open ▸ .

Figure 10.13 VMS Fishing Vessel Density (July 2018 – June 2021)

The highest density areas were to the north of the Proposed Development array area and within the northern part of Proposed Development array area. This correlates well with the long-term AIS data for fishing vessels during 2019 presented in Appendix E, noting that this also predates the start of Seagreen construction.

Comparison with volume 2, chapter 12

The baseline established in volume 2, chapter 12 indicates that overall commercial fishing activity is most prominent in coastal areas, particularly in the approaches to the Firth of Forth and much further north, south of Stonehaven. Activities around the Firth of Forth are dominated by demersal stern trawlers with activity further north dominated by scallop dredgers, with some contribution from whelkers/potters. The nationality of almost all fishing vessels observed was British.

This shows good agreement with the baseline established in this section, in terms of the fishing gear types and nationalities identified. In terms of the distribution of commercial fishing vessel activity, there is also reasonable agreement, noting that the extent of the Proposed Development array area shipping and navigation study area does not allow for detailed comparison in relation to coastal activities.

10.1.2.4  Oil and Gas Vessels

Vessel Traffic Survey Data

The tracks of oil and gas vessels recorded within the Proposed Development array area shipping and navigation study area throughout both survey periods are presented in Figure 10.14   Open ▸ .

Figure 10.14 Oil and Gas Vessel Traffic within Proposed Development Array Area Shipping and Navigation Study Area (28 Days Summer 2022 and Winter 2021)

Throughout the survey periods an average of one unique oil and gas vessel per day passed through the Proposed Development array area shipping and navigation study area. The majority of these vessels were on passage north-south between Aberdeen and gas fields in the Southern North Sea.

Those oil and gas vessels observed within the Seagreen buoyed construction area were recorded during the winter period, prior to the start of Seagreen construction.

Long-Term Vessel Traffic Data

Following consultation with the UK Chamber of Shipping and Forth Ports, it was confirmed that occasional vessel traffic movements associated with jack-ups, semi-submersibles and other platforms occur in the region.

Although no such activities were identified in the vessel traffic survey data, one such instance was identified in the long-term vessel traffic data; this involved an FPSO being towed by two tugs and supported by two other vessels east-west into Dundee, passing the Proposed Development array area at a minimum distance of approximately 1.8 nm. A plot showing this activity is presented in Appendix E, with Forth Ports confirming in consultation that such activities occur infrequently; based on arrivals data provided by Forth Ports there have been an average of eight rig callings per year at ports in the Forth and Tay in the seven-year period between 2015 and 2021.

10.1.2.5  Recreational Vessels

Vessel Traffic Survey Data

For the purposes of the NRA, recreational activity includes sailing and motor craft of between 2.4 and 24 m LOA. The tracks of recreational vessels recorded within the Proposed Development array area shipping and navigation study area throughout both survey periods are presented in Figure 10.15   Open ▸ .

Figure 10.15 Recreational Vessel Traffic within Proposed Development Array Area Shipping and Navigation Study Area (28 Days Summer 2022 and Winter 2021)

One recreational vessel per day was recorded within the Proposed Development array area shipping and navigation study area during the summer survey period, with none recorded during the winter survey period. All recreational vessels were recorded via AIS, with no recreational vessels recorded via radar.

RYA Coastal Atlas of Recreational Boating

In addition to the vessel traffic survey data, the RYA Coastal Atlas of Recreational Boating (RYA, 2019) has been reviewed for the region. The RYA Coastal Atlas may be used to “help identify and protect areas of importance to recreational boaters, to advise on new development proposals and in discussions over navigational safety”. The RYA Coastal Atlas includes a heat map indicating the density of recreational activity around the UK coast as well as features relevant to recreational boating such as general boating areas, clubs, training centres and marinas.

Figure 10.16   Open ▸ presents a plot of the RYA Coastal Atlas heat map relative to the Proposed Development array area. Following this, Figure 10.17   Open ▸ presents a plot of features relevant to recreational boating.

Figure 10.16 RYA Coastal Atlas Heat Map in Proximity to Proposed Development

Figure 10.17 RYA Coastal Atlas Features in Proximity to Proposed Development

Higher density recreational traffic is observed towards the coast and the Firth of Forth, with a gradual decrease culminating in sparse activity within the Proposed Development array area. There are a number of RYA facilities along the coast in the vicinity, with the nearest general boating area located approximately 13 nm west of the Proposed Development array area.

Consultation Feedback

During consultation, RYA Scotland stated that only around 20% to 25% of cruising vessels in the region transmit an AIS signal (see 9 March and 28 September 2021 entries in Table 4.1   Open ▸ ) and numbers should be multiplied by five to obtain a more accurate estimate of recreational activity. On this basis, from the long-term vessel traffic data (which consists of AIS only) there are estimated to be an average of two to three unique vessels per day.

The Forth Yacht Clubs Association indicated that smaller recreational vessels – which are less likely to carry AIS – generally route inshore of the Proposed Development array area (see 28 September 2021 entry in Table 4.1   Open ▸ ). This correlates with the density heat map and general boating areas from the RYA Coastal Atlas which highlight more coastal areas as popular for recreational vessels.

10.1.2.6  Passenger Vessels

Vessel Traffic Survey Data

Figure 10.18   Open ▸ presents the passenger vessels recorded within the Proposed Development array area study area during the summer survey period.

Figure 10.18 Passenger Vessel Traffic within Proposed Development Array Area Shipping and Navigation Study Area (14 Days Summer 2022)

An average of one to two unique passenger vessels per day were recorded within the Proposed Development shipping and navigation study area during the summer survey period, with all passenger vessels recorded being cruise liners on destinations to/from ports in the Firth of Forth. No passenger vessels were recorded within the Proposed Development array area shipping and navigation study area throughout the winter survey period, however. Following an assessment of long-term vessel traffic data (see Appendix E), it is concluded that this, as well as the lack of regularly scheduled passenger vessels, is likely a result of the COVID-19 pandemic which has had a substantial effect on shipping movements globally (see section 5.4.3).

Consultation Feedback

During consultation, Forth Ports confirmed that during the COVID-19 pandemic there were no visits by cruise ships to the Firth of Forth, but under normal circumstances there are around 125 visits per year by cruise ships. An estimated 170 passenger vessel transits were observed within the long-term vessel traffic data in and out of the Firth of Forth. However it is noted that the Proposed Development array area shipping and navigation study area does not capture all passenger vessel movements in and out of the Firth of Forth, and due to cruise schedules numbers are subject to fluctuation season on season.

10.1.3    Vessel Sizes

10.1.3.1  Vessel Length Overall

A plot of all vessel tracks (excluding temporary traffic) recorded within the Proposed Development array area shipping and navigation study area throughout the survey periods, colour-coded by length overall (LOA), is presented in Figure 10.19   Open ▸ . Following this, the distribution of these LOA classes by survey period is presented in Figure 10.20   Open ▸ .

Figure 10.19 Vessel Traffic Movements within Proposed Development Array Area Shipping and Navigation Study Area by Vessel LOA (28 Days Summer 2022 and Winter 2021)

Figure 10.20 Vessel LOA Distribution within Proposed Development Array Area and Shipping and Navigation Study Area (28-Days Summer 2022 and Winter 2021)

Vessel LOA was available for approximately 98% of vessels recorded in the Proposed Development array area shipping and navigation study area throughout both survey periods and ranged from 8 m for a potter fishing vessel to 330 m for three crude oil tankers.

Excluding the vessels for which an LOA was not available, the average LOA of all vessels within the Proposed Development array area shipping and navigation study area throughout the summer and winter survey periods was 89 m and 94 m, respectively.

10.1.3.2  Vessel Draught

A plot of all vessel tracks (excluding temporary traffic) recorded within the Proposed Development array area shipping and navigation study area throughout the survey periods, colour-coded by draught, is presented in Figure 10.21   Open ▸ . Following this, the distribution of these draught classes by survey period is presented in Figure 10.22   Open ▸ .

Figure 10.21 Vessel Traffic Movements within Proposed Development Array Area Shipping and Navigation Study Area by Vessel Draught (28 Days Summer 2022 and Winter 2021)

Figure 10.22 Vessel Draught Distribution within Proposed Development Array Area and Shipping and Navigation Study Area (28-Days Summer 2022 and Winter 2021)

Vessel draught was available for approximately 67% of vessels recorded in the Proposed Development array area shipping and navigation study area throughout both survey periods and ranged from 1.2 m for a wind farm support vessel to 20 m for a crude oil tanker.

Excluding the vessels for which a draught was not available, the average draught of all vessels within the Proposed Development array area shipping and navigation study area throughout the summer and winter survey periods was 5.2 m and 5.8 m, respectively.

10.1.4    Anchoring Activity

Anchored vessels can be identified based upon the AIS navigational status which is programmed on the AIS transmitter on board a vessel. However, information is manually entered into the AIS, and therefore it is common for vessels not to update their navigational status if only at anchor for a short period of time.

For this reason, those vessels which travelled at a speed of less than 1 kt for more than 30 minutes had their corresponding vessel tracks individually checked for patterns characteristic of anchoring activity. After applying these criteria, no vessels were deemed to be at anchor within the Proposed Development array area shipping and navigation study area.

10.2   Proposed Development Export Cable Corridor

10.2 Proposed Development Export Cable Corridor

A number of tracks recorded during the Proposed Development export cable corridor survey periods were classified as temporary (non-routine), such as the tracks of non-routine survey vessels and vessels associated with the construction of NnG. These have therefore been excluded from the analysis.

A plot of the vessel tracks recorded during a 14-day survey period in July 2020, colour-coded by vessel type and excluding temporary traffic, is presented in Figure 10.23   Open ▸ . A plot of the vessel tracks recorded during a further 14-day survey period in January 2021, colour-coded by vessel type and excluding temporary traffic, is presented in Figure 10.24   Open ▸ .

Figure 10.23 Vessel Traffic Movements within Proposed Development Export Cable Corridor Shipping and Navigation Study Area by Vessel Type (14 Days Summer 2022)

Figure 10.24 Vessel Traffic Movements within Proposed Development Export Cable Corridor Shipping and Navigation Study Area by Vessel Type (14 Days Winter 2021)

Plots of the vessel tracks for the summer and winter survey periods converted to a density heat map are presented in Figure 10.25   Open ▸ and Figure 10.26   Open ▸ , respectively.

Figure 10.25 Vessel Density Heat Map within Proposed Development Export Cable Corridor Shipping and Navigation Study Area (14 Days Summer 2022)

Figure 10.26 Vessel Density Heat Map within Proposed Development Export Cable Corridor Shipping and Navigation Study Area (14 Days Winter 2021)

10.2.1    Vessel Counts

For the 14 days analysed in the summer survey period, there was an average of 29 unique vessels per day recorded within the Proposed Development export cable corridor shipping and navigation study area. In terms of vessels intersecting the Proposed Development export cable corridor itself, there was an average of 25 unique vessels per day.

The daily number of unique vessels recorded within the Proposed Development export cable corridor shipping and navigation study area and the Proposed Development export cable corridor itself during the summer survey period are presented in Figure 10.27   Open ▸ . Since the survey commenced and concluded midway through the first and last days of the summer survey period (as described in section 5.2), the first and last days are partial.

Figure 10.27 Unique Vessels per Day within the Proposed Development Export Cable Corridor Area and Shipping and Navigation Area (14 Days Summer 2022)

Throughout the summer survey period approximately 87% of unique vessel tracks recorded within the Proposed Development export cable corridor shipping and navigation study area intersected the Proposed Development export cable corridor itself.

The busiest day recorded within the Proposed Development export cable corridor shipping and navigation study area throughout the summer survey period was 4 August when 39 unique vessels were recorded. The busiest day recorded within the Proposed Development export cable corridor itself throughout the summer survey period was 5 August when 34 unique vessels were recorded.

The quietest full day recorded within the Proposed Development export cable corridor shipping and navigation study area throughout the summer survey period was 7 August when 18 unique vessels were recorded. The quietest full day recorded within the Proposed Development export cable corridor itself throughout the summer survey period was also 7 August when 15 unique vessels were recorded.

For the 14 days analysed in the winter survey period, there was an average of 19 unique vessels per day recorded within the Proposed Development export cable corridor shipping and navigation study area. In terms of vessels intersecting the Proposed Development export cable corridor itself, there was an average of 18 unique vessels per day.

The daily number of unique vessels recorded within the Proposed Development export cable corridor shipping and navigation study area and the Proposed Development export cable corridor itself are presented in Figure 10.28   Open ▸ .

Figure 10.28 Unique Vessels per Day within the Proposed Development Export Cable Corridor Area and Shipping and Navigation Study Area (14 Days Winter 2021)

Throughout the winter survey period approximately 92% of unique vessel tracks recorded within the Proposed Development export cable corridor shipping and navigation study area intersected the Proposed Development export cable corridor itself.

The busiest day recorded within the Proposed Development export cable corridor shipping and navigation study area throughout the winter survey period was 19 January when 27 unique vessels were recorded. The busiest days recorded within the Proposed Development export cable corridor itself throughout the winter survey period was 24 January when 24 unique vessels were recorded.

The quietest days recorded within the Proposed Development export cable corridor shipping and navigation study area throughout the winter survey period were 14 January and 16 January when 13 unique vessels were recorded each. The quietest day recorded within the Proposed Development export cable corridor itself throughout the winter survey period was 11 January when 11 unique vessels were recorded.

10.2.2    Vessel Types

The percentage distribution of the main vessel types recorded within the Proposed Development export cable corridor shipping and navigation study area is presented in Figure 10.29   Open ▸ .

Figure 10.29 Vessel Type Distribution within Proposed Development Export Cable Corridor Area and Shipping and Navigation Study Area (28 Days Summer 2022 and Winter 2021)

Throughout the summer period, the most common vessel types in the Proposed Development export cable corridor shipping and navigation study area were fishing vessels (31%), tankers (22%), cargo vessels (16%), and recreational vessels (16%). Throughout the winter period, the most common vessel types were tankers (36%), cargo vessels (33%), and fishing vessels (20%).

Although cruise liners were recorded within the Proposed Development export cable corridor study area during the summer period, no commercial ferries were identified in the winter period, which aligns with feedback provided by Forth Ports during consultation (see 10 June 2020 entry in Table 4.1   Open ▸ ).

10.2.2.1  Tankers

The tracks of tankers recorded within the Proposed Development export cable corridor shipping and navigation study area throughout both survey periods are presented in Figure 10.30   Open ▸ .

Figure 10.30 Tanker Traffic within Proposed Development Export Cable Corridor Shipping and Navigation Study Area (28 Days Summer 2022 and Winter 2021)

Throughout the survey periods, an average of between six and seven tankers per day were recorded within the Proposed Development export cable corridor shipping and navigation study area. Regular tanker routeing included coastal transits out of the Firth of Forth.

Tanker subtypes recorded in the Proposed Development export cable corridor shipping and navigation study area included oil/chemical tankers (31%), LPG tankers (27%), and oil product tankers (22%).

10.2.2.2  Commercial Fishing Vessels

Vessel Traffic Data

The tracks of commercial fishing vessels recorded within the Proposed Development export cable corridor shipping and navigation study area throughout both survey periods, are presented in Figure 10.31   Open ▸ .

Figure 10.31 Commercial Fishing Vessel Traffic within Proposed Development Export Cable Corridor Shipping and Navigation Study Area (28 Days Summer 2022 and Winter 2021)

Throughout the survey periods an average of six commercial fishing vessels per day were recorded within the Proposed Development export cable corridor shipping and navigation study area. All the commercial fishing vessels were recorded via AIS with no recreational vessels recorded via radar. Although AIS is only mandatory for fishing vessels greater than 15 m LOA, 46% of the commercial fishing vessels recorded using AIS were under 15 m LOA.

Fishing gear type could not be identified for 52% of the commercial fishing vessels recorded. The most common fishing gear types recorded in the Proposed Development export cable corridor shipping and navigation study area during the survey periods were demersal trawlers (70%), twin trawlers (13%), and potters (11%).

The nationality of all commercial fishing vessels recorded was British.

Vessel Monitoring System Data

In addition to the vessel traffic survey data, VMS data recorded between July 2018 and June 2021 has also been analysed within the Proposed Development export cable corridor shipping and navigation study area. A density grid, using the VMS data during this period as input, is presented in Figure 10.32   Open ▸ .

Figure 10.32 VMS Fishing Density within Proposed Development Export Cable Corridor Shipping and Navigation Study Area (July 2018 – June 2021)

Similarly to the AIS data, the nearshore areas recorded the highest density of VMS fishing activity, with moderate density recorded on the eastern edge of the Proposed Development export cable corridor shipping and navigation study area.

Comparison with volume 2, chapter 12

The baseline established in volume 2, chapter 12 indicates that overall commercial fishing activity is most prominent in coastal areas, particularly in the approaches to the Firth of Forth, where the Proposed Development export cable corridor makes landfall. Activities around the Proposed Development export cable corridor are dominated by trawlers and the nationality of almost all fishing vessels observed was British.

This shows good agreement with the baseline established in this section, in terms of the fishing gear types and nationalities identified. In terms of the distribution of commercial fishing vessel activity, there is also reasonable agreement, with the majority of activity occurring in coastal areas rather than the portion of the Proposed Development export cable corridor further offshore.

10.2.2.3  Cargo Vessels

The tracks of cargo vessels recorded within the Proposed Development export cable corridor shipping and navigation study area throughout both survey periods are presented in Figure 10.33   Open ▸ .

Figure 10.33 Cargo Vessel Traffic within Proposed Development Export Cable Corridor Shipping and Navigation Study Area (28 Days Summer 2022 and Winter 2021)

Throughout the survey periods an average of five unique cargo vessels per day were recorded within the Proposed Development export cable corridor shipping and navigation study area. Regular cargo vessel routeing included coastal transits out of the Firth of Forth.

Cargo vessel subtypes recorded in the Proposed Development export cable corridor shipping and navigation study area included general cargo (64%) and container vessels (29%).

10.2.2.4  Recreational Vessels

Vessel Traffic Data

The tracks of recreational vessels recorded within the Proposed Development export cable corridor shipping and navigation study area throughout both survey periods are presented in Figure 10.34   Open ▸ .

Figure 10.34 Recreational Vessel Traffic within Proposed Development Export Cable Corridor Shipping and Navigation Study Area (28 Days Summer 2022 and Winter 2021)

An average of approximately four to five recreational vessels per day were recorded within the Proposed Development export cable corridor shipping and navigation study area during the summer survey period, with none recorded during the winter survey period. All recreational vessels were recorded via AIS, with no recreational craft recorded on radar.

RYA Coastal Atlas of Recreational Boating

Figure 10.16   Open ▸ presents a plot of the RYA Coastal Atlas heat map relative to the Proposed Development export cable corridor. Following this, Figure 10.17   Open ▸ presents a plot of features relevant to recreational boating.

The RYA Coastal Atlas shows good correlation with the AIS data, in that the majority of recreational activity is coastal.

10.2.2.5  Oil and Gas Vessels

The tracks of oil and gas vessels recorded within the Proposed Development export cable corridor shipping and navigation study area throughout both survey periods, are presented in Figure 10.35   Open ▸ .

Figure 10.35 Oil and Gas Vessel Traffic within Proposed Development Export Cable Corridor Shipping and Navigation Study Area (28 Days Summer 2022 and Winter 2021)

Throughout the survey periods, an average of approximately one oil and gas vessel per day passed within the Proposed Development export cable corridor shipping and navigation study area. The majority of these vessels were on passage north-south between Aberdeen and gas fields in the Southern North Sea.

10.2.2.6  Passenger Vessels

Vessel Traffic Data

Throughout the survey periods, an average of approximately one passenger vessel per day passed within the Proposed Development export cable corridor shipping and navigation study area during the summer survey period, with none recorded during the winter survey period. Following an assessment of Anatec’s in-house ShipRoutes database, it is concluded that this is a result of the COVID-19 pandemic which has had a substantial effect on shipping movements globally (see section 5.4.3).

Anatec ShipRoutes Database

ShipRoutes includes one notable route featuring passenger vessels that passes through the Proposed Development export cable corridor, on a similar course to the main tanker route shown in Figure 10.30   Open ▸ . This route crosses the North Sea between the Firth of Forth and Hamburg[7] and constitutes approximately 110 transits per year (one vessel every three to four days).

This correlates with feedback received from Forth Ports during consultation indicating that under normal circumstances, when the effects of the COVID-19 pandemic are not present, there are around 125 visits per year by cruise ships to the Forth. It should be noted that the Proposed Development export cable corridor only covers one approach to the Forth and cruise schedules and numbers are subject to fluctuation season on season.

10.2.3    Vessel Sizes

10.2.3.1  Vessel Length

A plot of all vessel tracks (excluding temporary traffic) recorded within the Proposed Development export cable corridor shipping and navigation study area throughout the survey periods, colour-coded by LOA, is presented in Figure 10.36   Open ▸ . Following this, the distribution of these LOA classes by survey period is presented in Figure 10.37   Open ▸ .

Figure 10.36 Vessel Traffic Movements within Proposed Development Export Cable Corridor Shipping and Navigation Study Area by Vessel LOA (28 Days Summer 2022 and Winter 2021)

Figure 10.37 Vessel LOA Distribution within Proposed Development Export Cable Corridor and Shipping and Navigation Study Area (28 Days Summer 2022 and Winter 2021)

Vessel LOA was available for approximately 89% of vessels recorded in the Proposed Development export cable corridor shipping and navigation study area throughout both survey periods and ranged from 5 m for a RNLI lifeboat to 330 m for two crude oil tankers.

Excluding the vessels for which an LOA was not available, the average LOA of all vessels within the Proposed Development export cable corridor shipping and navigation study area throughout the summer and winter survey periods was 69 m and 98 m, respectively.

10.2.3.2  Vessel Draught

A plot of all vessel tracks (excluding temporary traffic) recorded within Proposed Development export cable corridor shipping and navigation study area throughout the survey periods, colour-coded by draught, is presented in Figure 10.38   Open ▸ . Following this, the distribution of these draught classes by survey period is presented in Figure 10.39   Open ▸ .

Figure 10.38 Vessel Traffic Movements within Proposed Development Export Cable Corridor Shipping and Navigation Study Area by Vessel Draught (28 Days Summer 2022 and Winter 2021)

Figure 10.39 Vessel Draught Distribution within Berwick Bank Export Cable Corridor and Shipping and Navigation Study Area (28 Days Summer 2022 and Winter 2021)

Vessel draught was available for approximately 50% of vessels recorded in the Proposed Development export cable corridor shipping and navigation study area throughout both survey periods and ranged from 0.9 m for a fishing vessel to 20 m for a crude oil tanker.

Excluding the vessels for which a draught was not available, the average draught of all vessels within the Proposed Development export cable corridor shipping and navigation study area throughout the summer and winter survey periods was 4.6 m and 5.3 m respectively.

10.2.4    Anchoring Activity

The same criteria outlined in section 10.1.4 for identifying anchored vessels bas been applied to the vessel traffic data for the Proposed Development export cable corridor shipping and navigation study area.

After applying these criteria, no vessels were deemed to be at anchor within the Proposed Development export cable corridor shipping and navigation study area.

11 Base Case Vessel Routeing

11 Base Case Vessel Routeing

11.1   Definition of a Main Commercial Route

11.1 Definition of a Main Commercial Route

Main commercial routes have been identified using the principles set out in MGN 654 (MCA, 2021). Vessel traffic data are assessed and vessels transiting at similar headings and locations are identified as a main route. To help identify main routes, vessel traffic data can also be interrogated to show vessels (by name and/or operator) that frequently transit those routes. The route width is then calculated using the 90th percentile rule from the median line of the potential shipping route as shown in Figure 11.1   Open ▸ . Additionally, the outputs of consultation undertaken with local stakeholders assisted in the identification of the main commercial routes.

Figure 11.1 Illustration of Main Route Calculation (MCA, 2021)

11.2   Pre Wind Farm Main Commercial Routes

11.2 Pre Wind Farm Main Commercial Routes

A total of 15 main commercial routes were identified within the Proposed Development array area shipping and navigation study area from the vessel traffic survey data[8] and consultation. These main commercial routes and corresponding 90th percentiles within the Proposed Development array area shipping and navigation study area are shown relative to the Proposed Development array area in Figure 11.2   Open ▸ . Following this, a description of each route is provided in Table 11.1   Open ▸ , including the average number of vessels per day, start and end locations and main vessel types. It is noted that the start and end locations are based on the most common destinations transmitted via AIS by vessels on those routes.

To ensure all main commercial routes are captured, the long-term vessel traffic data has been used to validate the main commercial routes identified from the vessel traffic survey data, with consideration given to the change in vessel traffic movements due to the presence of Seagreen.

Figure 11.2 Main Commercial Routes and 90th Percentiles within Proposed Development Array Area Shipping and Navigation Study Area (Pre Wind Farm)             

Table 11.1 Description of Main Commercial Routes

There is likely additional routeing in and out of the Firth of Forth which falls outside of the Proposed Development array area shipping and navigation study area. This includes tankers headed for Braefoot Bay which may be located further inshore, as noted by Forth Ports during consultation (see 12 June 2020 entry in Table 4.1   Open ▸ ) and passenger vessels (as noted in section 10.1.2.6). Given the distance from the Proposed Development array area, it is not anticipated that such routeing will be affected by the presence of the Proposed Development in isolation. However, such routeing is considered in the assessment of cumulative deviations where appropriate (see section 15.6.2).

12 Adverse Weather Vessel Traffic Movements

12 Adverse Weather Vessel Traffic Movements

Some vessels and vessel operators may operate alternative routes during periods of adverse weather. This section focuses on vessel movements in adverse weather. Consideration is given to the implications of the presence of, or activities associated with, the Proposed Development during adverse weather. For example, if a commercial vessel is unable to make passage, or a small craft is unable to access safe havens.

Adverse weather includes wind, wave and tidal conditions as well as reduced visibility due to fog. Adverse weather can hinder a vessel’s standard route, its speed of navigation and/or its ability to enter the destination port. Adverse weather routes are assessed to be significant course adjustments to mitigate vessel motion in adverse weather conditions. When transiting in adverse weather conditions, a vessel is likely to encounter various types of weather and tidal phenomena, which may lead to severe roll motions, potentially causing damage to cargo, equipment and/or discomfort and danger to persons on board. The sensitivity of a vessel to these phenomena will depend on the actual stability parameters, hull geometry, vessel type, vessel size and speed.

12.1   Identification of Periods with Adverse Weather

12.1 Identification of Periods with Adverse Weather

Historical weather information provided by the Met Office (Met Office, 2019) has been used to identify periods of adverse weather during 2019 (the year covered by the long-term vessel traffic data) when routes within or in proximity to the Proposed Development could be considered most likely to be altered or cancelled. The key weather events identified are detailed in Table 12.1   Open ▸ .

Table 12.1 Key Weather Events During 2019 Relevant to the Proposed Development (Met Office)

12.2   Commercial Routeing Changes

12.2 Commercial Routeing Changes

The long-term vessel traffic data has been used to identify potential commercial routeing activity related to adverse weather conditions within and in proximity to the Proposed Development, with the periods outlined in Table 12.1   Open ▸ studied most closely.

No substantial alternative routeing was observed. However, during consultation adverse weather routeing was raised by the MCA as a topic that requires attention (see 9 March 2021 entry in Table 4.1   Open ▸ ). This was reflected in feedback received during the second Hazard Workshop, including from Forth Ports indicating that the region is known to experience significant bad weather. The FMA highlighted the Marr Bank as a particular hazard of note for larger tankers navigating coastally in adverse weather (see 27 July 2022 entries in Table 4.1   Open ▸ ).

Given the coastal nature of vessel routeing in the region, it is highly likely that many vessels choose to navigate a course that minimises exposure to any adverse weather, whilst also accounting for other factors, such as journey time. Route 1 in Figure 11.2   Open ▸ is such an example of a route where the optimal passage for minimising journey time has been conceded in favour of a passage which keeps a closer distance to the UK east coast where there is greater shelter from adverse weather. This also aligns with feedback from Intrada Ship Management during consultation (see 15 December 2021 entry in Table 4.1   Open ▸ ).

Therefore, the potential for adverse weather hazards due to deviations of main commercial routes has been considered when determining deviations for both the Proposed Development in isolation (see section 15.5) and cumulative scenarios (see section 15.6).

In consultation feedback Intrada Ship Management noted that given their vessels carry deck cargoes they are particularly sensitive to rolling and pitching and will need adequate sea room in order to select headings that mitigate the risks associated with weather/tidal direction.

12.3   Small Craft Use of Safe Havens

12.3 Small Craft Use of Safe Havens

As indicated by the long-term vessel traffic data, RYA Coastal Atlas of Recreational Boating (RYA, 2019) and consultation feedback, recreational vessel activity predominantly occurs inshore of the Proposed Development array area (and the other offshore wind farm developments in the region) and therefore it is not anticipated that the presence of the Proposed Development array area or associated activities will have a substantial effect on the ability of small craft to access safe havens in adverse weather conditions.

For the less frequent cases of recreational vessels navigating further offshore, the Scottish Whitefish Producers Association indicated that the overall minimum spacing between structures proposed (1,000 m) may not be sufficient for safe navigation. However, this minimum spacing is greater than that present at most existing offshore wind farm developments in the UK, some of which have much greater volumes of small craft activity associated with them (e.g. Rampion Offshore Wind Farm in the English Channel). Figure 12.1   Open ▸ presents an indicative small craft of length 15 m navigating internally within an offshore wind farm array with 1,000 m spacing between structures.

Figure 12.1 Indicative Small Craft Navigating within Wind Farm Array

There is substantial sea room available for a small craft to navigate safely, including in the majority of adverse weather conditions. As per International Convention on the Safety of Life at Sea (SOLAS) Chapter V (IMO, 1974), all vessels at sea are required to passage plan and part of the passage planning process requires them to consider weather forecasts and subsequent conditions. It is anticipated that vessels would then take account of these forecasts prior to embarking on a passage through or offshore of the array.

Taking into account the need for consultation on the final array layout post consent and the requirements of SOLAS Chapter V, there are not considered to be any significant effect on access to safe havens due to the presence of the Proposed Development or associated activities.

13 Navigation, Communication and Position Fixing Equipment

13 Navigation, Communication and Position Fixing Equipment

This section discusses the potential hazards upon the navigation, communication, and position-fixing equipment of vessels that may arise due to the infrastructure associated with the Proposed Development.

13.1   Very High Frequency Communications (Including Digital Selective Calling)

13.1 Very High Frequency Communications (Including Digital Selective Calling)

In 2004, trials were undertaken at the North Hoyle Offshore Wind Farm, located off the coast of North Wales. As part of these trials, tests were undertaken to evaluate the operational use of typical small-vessel VHF transceivers (including Digital Selective Calling (DSC)) when operated close to wind turbines.

The wind turbines had no noticeable effect on voice communications within the array or ashore. It was noted that if small craft vessel to vessel and vessel to shore communications were not significantly affected by the presence of wind turbines, then it is reasonable to assume that larger vessels with higher powered, and more efficient, systems would also be unaffected.

During this trial, a number of telephone calls were made from ashore, within the array, and on its offshore side. No effects were recorded using any system provider (MCA and QinetiQ, 2004).

Furthermore, as part of SAR trials carried out at the North Hoyle Offshore Wind Farm in 2005, radio checks were undertaken between the Sea King helicopter, and both Holyhead and Liverpool coastguards. The aircraft was positioned to the offshore side of the array, and communications were reported as very clear with no apparent degradation of performance. Communications with the service vessel located within the array were also fully satisfactory throughout the trial (MCA, 2005).

In addition to the North Hoyle trials, a desk-based study was undertaken for the Horns Rev 3 Offshore Wind Farm in Denmark in 2014, and it was concluded that there were not expected to be any conflicts between point to point radio communications networks, and no interference upon VHF communications (Energinet, 2014).

Following consideration of these reports, and noting that since the trials above there have been no significant issues with regards to VHF observed or reported, the presence of the Proposed Development is anticipated to have no significant risk upon VHF communications.

13.2   Very High Frequency Direction Finding

13.2 Very High Frequency Direction Finding

During the North Hoyle Offshore Wind Farm trials in 2004, the VHF Direction Finding (DF) equipment carried in the trial boats did not function correctly when very close to wind turbines (within approximately 50 m). This is deemed to be a relatively small-scale risk due to the limited use of VHF DF equipment and will not impact operational or SAR activities (MCA and QinetiQ, 2004).

Throughout the 2005 SAR trials carried out at North Hoyle, the Sea King radio homer system was tested. The Sea King radio homer system utilises the lateral displacement of a vertical bar on an instrument to indicate the sense of a target relative to the aircraft heading. With the aircraft and the target vessel within the array at a range of approximately 1 nm, the homer system operated as expected with no apparent degradation.

Since the trials detailed above, no significant issues with regards to VHF DF have been observed or reported, and therefore the presence of the Proposed Development is anticipated to have no significant risk upon VHF DF equipment.

13.3   Automatic Identification System

13.3 Automatic Identification System

No significant issues with interference to AIS transmission from operational offshore wind farms have been observed or reported to date. Such interference was also absent in the trials carried out at the North Hoyle Offshore Wind Farm (MCA and QinetiQ, 2004).

In theory, there could be interference when there is a structure located between the transmitting and receiving antennas (i.e. blocking line of sight) of the AIS. However, given no issues have been reported to date at operational developments or during trials, no significant risk is anticipated due to the presence of the Proposed Development.

13.4   Navigational Telex System

13.4 Navigational Telex System

The Navigational Telex (NAVTEX) system is used for the automatic broadcast of localised Maritime Safety Information (MSI) and either prints it out in hard copy or displays it on a screen, depending upon the model.

There are two NAVTEX frequencies. All transmissions on NAVTEX 518 Kilohertz (kHz), the international channel, are in English. NAVTEX 518 kHz provides the mariner (both recreational and commercial) with weather forecasts, severe weather warnings, and navigation warnings such as obstructions or buoys off-station. Depending on the user’s location, other information options may be available such as ice warnings for high latitude sailing.

The 490 kHz national NAVTEX service may be transmitted in the local language. In the UK, full use is made of this secondary frequency including useful information for smaller craft, such as the inshore waters forecast and actual weather observations from weather stations around the coast.

Although no specific trials have been undertaken, no significant effect on NAVTEX has been reported to date at operational developments, and therefore no significant risk is anticipated due to the presence of the Proposed Development.

13.5   Global Positioning System

13.5 Global Positioning System

Global Positioning System (GPS) is a satellite-based navigational system. GPS trials were also undertaken throughout the 2004 trials at North Hoyle Offshore Wind Farm, and it was stated that “no problems with basic GPS reception or positional accuracy were reported during the trials”.

The additional tests showed that “even with a very close proximity of a wind turbine to the GPS antenna, there were always enough satellites elsewhere in the sky to cover for any that might be shadowed by the wind turbine tower” (MCA and QinetiQ, 2004).

Therefore, there are not expected to be any significant risks associated with the use of GPS systems within or in proximity to the Proposed Development, noting that there have been no reported issues relating to GPS within or in proximity to any operational offshore wind farms to date.

13.6   Electromagnetic Interference

13.6 Electromagnetic Interference

A compass, magnetic compass, or mariner's compass is a navigational instrument for determining direction relative to the earth's magnetic poles. It consists of a magnetised pointer (usually marked on the north end) free to align itself with the earth's magnetic field. A compass can be used to calculate heading, used with a sextant to calculate latitude, and with a marine chronometer to calculate longitude.

Like any magnetic device, compasses are affected by nearby ferrous materials as well as by local electromagnetic forces, such as magnetic fields emitted from power cables. As the compass still serves as an essential means of navigation in the event of power loss or as a secondary source, it is important that potential impacts from Electromagnetic Field (EMF) should be minimised to ensure continued safe navigation. The vast majority of commercial traffic uses non-magnetic gyrocompasses as the primary means of navigation, which are unaffected by EMF. Therefore, it is considered highly unlikely that any interference from EMF as a result of the presence of cables associated with the Proposed Development will have a significant impact on vessel navigation. However some smaller craft (fishing or leisure) may rely on them as their sole means of navigation

The export and inter-array cables for the Proposed Development could be Alternating Current (AC), Direct Current (DC) or a combination of both. Studies indicate that AC does not emit an EMF significant enough to impact marine magnetic compasses (Convention for the Protection of the Marine Environment of the North-East Atlantic (OSPAR), 2008).

The Moray Offshore Renewables Environmental Statement (Moray Offshore Renewables, 2012) notes that for both buried and protected DC cables the magnetic field will decrease exponentially with vertical distance from the seabed and with horizontal distance from the cables (within a few metres), irrespective of whether cables are buried or protected. It states that “in all cases, where cables are buried to 1 m depth, the predicted magnetic field is expected to be below the earth’s magnetic field (assumed to be 50 microtesla (µT)). Where DC cables cannot be buried and are instead protected, the magnetic field is expected to be below the earth’s magnetic field within 5 m from the seabed”.

The following are therefore considered to be important factors affecting the likelihood of EMF to affect compass deviation as a result of the presence of cables:

• water depth;
• burial depth (or protection);
• type of current (alternating or direct) running through the cables; and/or
• spacing or separation of the cables.

13.7   EMF from Cables Associated with the Proposed Development

13.7 EMF from Cables Associated with the Proposed Development

Within their response (16 November 2021) to the Berwick Bank Wind Farm Scoping Report the MCA stated that a compass deviation of three degrees will be accepted for 95% of the cable route and a five degree deviation accepted for the remaining 5% (see 16 November 2021 entry in Table 4.1   Open ▸ ). Table 13.1   Open ▸ details assumed EMF mitigation for the Proposed Development.

Table 13.1 EMF Mitigation

Given that 95% of the offshore export cables will be buried and 99.1% (approximately) of it in water depths greater than 10 m there are not anticipated to be any effects on compass deviation for the majority of the Proposed Development export cable corridor. Within shallow waters effects of EMF will be mitigated by the offshore export cables being either Horizontally Direction Drilled (HDD) or direct piped (within up to 1,500 m of the LAT mark and also out to a minimum of -5 m LAT) and also buried or protected as required beyond the point of emergence. As noted in Moray Offshore Renewables Environmental Statement (Moray Offshore Renewables, 2012) “where DC cables cannot be buried and are instead protected, the magnetic field is expected to be below the earth’s magnetic field within 5 m from the seabed” and there are negligible effects on magnetic compasses. Therefore, in summary based on mitigations of water depth, burial and use of HDD/direct pipes within shallow water the Proposed Development is anticipated to be within the requirements defined by the MCA.

Inter-array cables have not been considered within this section but are considered within acceptable limits given water depths within the Proposed Development array area (33 to 69 m Chart Datum) and use of burial/protection methods as required.

13.7.1    Electromagnetic Fields and Structures

MGN 654 (MCA, 2021) notes that small vessels with simple magnetic steering and hand bearing compasses should be wary of using these close to wind turbines as with any structure in which there is a large amount of ferrous material (MCA and QinetiQ, 2004). Potential effects are therefore deemed to be within acceptable levels when considered alongside other mitigation such as the mariner being able to make visual observations (not wholly reliant on the magnetic compass), lighting, sound signals and identification marking in line with MGN 654 (MCA, 2021).

13.7.2    Electromagnetic Fields to Date within Operational Offshore Wind Farms

No issues with respect to magnetic compasses have been reported to date in any of the trials (MCA and QinetiQ, 2004) carried out (inclusive of SAR helicopters) nor in any published reports from other operational offshore wind farms.

13.8   Marine Radar

13.8 Marine Radar

This section summarises trials and studies undertaken in relation to radar effects from offshore wind farms in the UK. It is important to note that since the time of the trials and studies discussed, wind turbine technology has advanced significantly, most notably in terms of the size of wind turbines available to be installed and utilised. The use of these larger wind turbines allows for a greater spacing between wind turbines than was achievable at the time of the studies being undertaken, which is beneficial in terms of radar interference effects (and surface navigation in general) as detailed in sections 15.7.1 to 15.7.5.

13.8.1    Trials

During the early years of offshore renewables within the UK, maritime regulators undertook a number of trials (both shore-based and vessel-based) into the effects of wind turbines on the use and effectiveness of marine radar.

In 2004, trials undertaken at the North Hoyle Offshore Wind Farm (MCA, 2004) identified areas of concern regarding the potential risks to marine- and shore-based radar systems due to the large vertical extents of the wind turbines (based on the technology at that time). This resulted in radar responses strong enough to produce interfering side lobes and reflected echoes (often referred to as false targets or ghosts).

Side lobe patterns are produced by small amounts of energy from the transmitted pulses that are radiated outside of the narrow main beam. The effects of side lobes are most noticeable within targets at short range (below 1.5 nm) and with large objects. Side lobe echoes form either an arc on the radar screen similar to range rings, or a series of echoes forming a broken arc, as illustrated in Figure 13.1   Open ▸ .

Figure 13.1 Illustration of Side Lobes on Radar Screen

Multiple reflected echoes are returned from a real target by reflection from some object in the radar beam. Indirect echoes or ‘ghost’ images have the appearance of true echoes but are usually intermittent or poorly defined; such echoes appear at a false bearing and false range, as illustrated in Figure 13.2   Open ▸ .

Figure 13.2 Illustration of Multiple Reflected Echoes on Radar Screen

Based on the results of the North Hoyle trials, the MCA produced a Shipping Route Template designed to give guidance to mariners on the distances which should be established between shipping routes and offshore wind farms. The latest version of the Shipping Route Template is included in MGN 654 (MCA, 2021).

A second set of trials conducted at Kentish Flats Offshore Wind Farm in 2006 on behalf of the British Wind Energy Association (BWEA) – now called RenewableUK (BWEA, 2007) – also found that radar antennas which are sited unfavourably with respect to components of the vessel’s structure can exacerbate effects such as side lobes and reflected echoes. Careful adjustment of radar controls suppressed these spurious radar returns, but mariners were warned that there is a consequent risk of losing targets with a small radar cross section, which may include buoys or small craft, particularly yachts or Glass Reinforced Plastic (GRP) constructed craft; therefore, due care should be taken in making such adjustments.

Theoretical modelling of the effects of the development of the proposed Atlantic Array Offshore Wind Farm, which was to be located off the south coast of Wales, on marine radar systems was undertaken by the Atlantic Array project (Atlantic Array, 2012) and considered a wider spacing of wind turbines than were considered within the early trials. The main outcomes of the modelling were the following:

• Multiple and indirect echoes were detected under all modelled parameters.
• The main effects noticed were stretching of targets in azimuth (horizontal) and appearance of ghost targets.
• There was a significant amount of clear space amongst the returns to ensure recognition of vessels moving amongst the wind turbines and safe navigation.
• Even in the worst case with radar operator settings artificially set to be poor, there is significant clear space around each wind turbine that does not contain any multipath or side lobe ambiguities to ensure safe navigation and allow differentiation between false and real (both static and moving) targets.
• Overall, it was concluded that the amount of shadowing observed was very little (noting that the model considered lattice-type foundations which are sufficiently sparse to allow radar energy to pass through).
• The lower the density of wind turbines the easier it is to interpret the radar returns and fewer multipath ambiguities are present.
• In dense, target rich environments, S-Band radar scanners suffer more severely from multipath effects in comparison to X-Band radar scanners.
• It is important for passing vessels to keep a reasonable separation distance between the wind turbines in order to minimise the effect of multipath and other ambiguities.
• The Atlantic Array study undertaken in 2012 noted that the potential for radar interference was mainly a problem during periods of reduced visibility when mariners may not be able to visually confirm the presence of other vessels in proximity (those without AIS installed which are usually fishing and recreational craft). It is noted that this situation would arise with or without wind turbines in place.
• There is potential for the performance of a vessel’s Automatic Radar Plotting Aid (ARPA) to be affected when tracking targets in or near the array. Although greater vigilance is required, during the Kentish Flats trials it was shown that false targets were quickly identified as such by the mariners and then by the equipment itself.

In summary, experience in UK waters has shown that mariners have become increasingly aware of any radar effects as more offshore wind farms become operational. Based on this experience, the mariner can interpret the effects correctly, noting that effects are the same as those experienced by mariners in other environments such as in close proximity to other vessels or structures. Effects can be effectively mitigated by “careful adjustment of radar controls”.

The MCA has also produced guidance to mariners operating in proximity to OREIs in the UK which highlights radar issues amongst others to be taken into account when planning and undertaking voyages in proximity to OREIs (MCA, 2008). The interference buffers presented in Table 13.2   Open ▸ are primarily based on MGN 654 (MCA, 2021) but also consider the content of MGN 371 (MCA, 2008), MGN 543 (MCA, 2016) and MGN 372 (MCA, 2008).

Table 13.2 Distances at which Risks for Marine Radar Occur

As noted in Table 13.2   Open ▸ , the onset range from the wind turbines of false returns is approximately 1.5 nm, with progressive deterioration in the radar display as the range closes. If interfering echoes develop, the requirements of the Convention on International Regulations for Preventing Collisions at Sea (COLREGs) Rule 6 Safe Speed are particularly applicable and must be observed with due regard to the prevailing circumstances (IMO, 1972/77). In restricted visibility, Rule 19 Conduct of Vessels in Restricted Visibility applies and compliance with Rule 6 becomes especially relevant. In such conditions mariners are required, under Rule 5 Look-out to take into account information from other sources which may include sound signals and VHF information, for example from a VTS or AIS (MCA, 2016).

13.8.2    Experience from Operational Developments

The evidence from mariners operating in proximity to existing offshore wind farms is that they quickly learn to adapt to any effects. The example of the Galloper and Greater Gabbard Offshore Wind Farms, which are located in proximity to IMO routeing measures is presented in Figure 13.3   Open ▸ . Despite this proximity to heavily trafficked Traffic Separation Scheme lanes, there have been no reported incidents or issues raised by mariners who operate within the vicinity. The interference buffers presented in Figure 13.3   Open ▸ are as per Table 13.2   Open ▸ .

Figure 13.3 Illustration of Potential Radar Interference at Greater Gabbard and Galloper Offshore Wind Farms

As indicated by Figure 13.3   Open ▸ , vessels utilising these Traffic Separation Scheme lanes experience some radar interference based on the available guidance. Both developments are operational, and each of the lanes is used by a minimum of five vessels per day on average. However, to date, there have been no incidents recorded (including any related to radar use), or concerns raised by the users.

AIS information can also be used to verify the targets of larger vessels (generally vessels over 15 m LOA – the minimum threshold for fishing vessel AIS carriage requirements). Approximately 15% of the vessel traffic recorded within the Proposed Development array area study area was under 15 m LOA, although throughout the vessel traffic surveys over 99% of vessels were recorded via AIS, indicating a high level of AIS take-up among vessels for which AIS carriage is not mandatory.

For any smaller vessels, particularly fishing vessels and recreational vessels, AIS Class B devices are becoming increasingly popular and allow the position of these small craft to be verified when in proximity to an offshore wind farm.

13.8.3    Increased Radar Returns

Beam width is the angular width, horizontal or vertical, of the path taken by the radar pulse. Horizontal beam width ranges from 0.75° to 5°, and vertical beam width ranges from 20° to 25°. How well an object reflects energy back towards the radar depends upon its size, shape, and aspect angle.

Larger wind turbines (either in height or width) will return greater target sizes and/or stronger false targets. However, there is a limit to which the vertical beam width would be affected (20° to 25°) dependent upon the distance from the target. Therefore, increased wind turbine height in the array will not create any effects in addition to those already identified from existing operational wind farms (interfering side lobes, multiple and reflected echoes).

Again, when taking into consideration the potential options available to marine users (such as reducing gain to remove false returns) and feedback from operational experience, this shows that the effects of increased returns can be managed effectively.

13.8.4    Fixed Radar Antenna Use in Proximity to an Operational Wind Farm

It is noted that there are multiple operational wind farms including Galloper that successfully operate fixed radar antenna from locations on the periphery of the array. These antennas are able to provide accurate and useful information to onshore coordination centres.

13.8.5    Application to the Proposed Development

Upon commissioning of the Proposed Development, some commercial vessels may pass within 1.5 nm of the wind farm structures and therefore may be subject to a minor level of radar interference. Trials, modelling, and experience from existing developments note that any risk can be mitigated by adjustment of radar controls.

An illustration of potential radar interference due to the Proposed Development and cumulative offshore wind farm developments is presented in Figure 13.4   Open ▸ . NnG is represented by the final array layout plotted on Admiralty Charts and Seagreen is represented by the final array layout published in the Safety Zone application (Seagreen Wind Energy Ltd, 2021), whereas Inch Cape is represented by the array area boundary published by Crown Estate Scotland, noting that a final array layout has not been published at the time of writing.

Figure 13.4 Illustration of Potential Radar Interference at the Proposed Development and Cumulative Offshore Wind Farm Developments

Vessels navigating internally within the Proposed Development array area will be subject to a greater level of radar interference, with risks becoming more substantial in close proximity to the wind turbines. This will require additional mitigation by vessels, including consideration of the navigational conditions (visibility) when passage planning and compliance with the COLREGs (IMO, 1972/77) will be essential.

For vessels transiting through the navigational corridor between the Proposed Development array area and Inch Cape, there may be a potential for increased exposure to radar interference depending upon the nature of the passage through the corridor. However, the distance and duration of the transit for which the distance from wind turbines will be less than 1.5 nm will be low and it is very unlikely that vessels will navigate within 0.5 nm of a wind turbine. Mitigations are available to vessels as listed throughout this section (e.g. adjustment of radar controls) and the risk is within parameters already safely managed at existing offshore wind farm developments.

Overall, the risk of marine radar interference is expected to be low and no further risk to navigational safety is anticipated outside the parameters which can be mitigated by operational controls. From existing experience within UK offshore wind farms, vessels do navigate safely internally within arrays including with spacing significantly less than at the Proposed Development array area.

13.9   Sound Navigation Ranging Systems

13.9 Sound Navigation Ranging Systems

No evidence has been found to date with regard to existing offshore wind farms to suggest that Sound Navigation Ranging (SONAR) systems produce any kind of SONAR interference which is detrimental to the fishing industry, or to military systems. No risk is therefore anticipated in relation to the presence of the Proposed Development.

13.10 Noise

13.10 Noise

No evidence has been found to date with regard to existing offshore wind farms to suggest that prescribed sound signals are in any way impacted by acoustic noise produced by the wind farm.

13.11 Summary of Risk

13.11 Summary of Risk

Based on the detailed technical assessment of the effects due to the presence of the Proposed Development on navigation, communication, and position fixing equipment in the previous subsections, the assessment of frequency and consequence and the resulting significance of risk for each topic is summarised in Table 13.3   Open ▸ .

Table 13.3 Summary of Risk on Navigation, Communication, and Position-fixing Equipment

On the basis of the NRA findings, associated risks are screened out of volume 2, chapter 13.

14 Cumulative and Transboundary Overview

14 Cumulative and Transboundary Overview

Cumulative risks have been considered for activities in combination and cumulatively with the Proposed Development. This section provides an overview of the baseline used to inform the cumulative risk assessment, including the developments and projects screened into the cumulative risk assessment based on the criteria outlined in section 3.3.

The outputs of the cumulative risk assessment are then provided in section 19.2.

14.1   Screened In Developments

14.1 Screened In Developments

14.1.1    Other Offshore Wind Farms

In addition to the Proposed Development, there are a number of other offshore wind farm developments in the outer Firth of Forth and Firth of Tay region and the UK east coast as a whole. Table 14.1   Open ▸ includes details of these offshore wind farm developments and includes the cumulative risk assessment scenario applied as well as whether each development is screened in or out of the cumulative risk assessment based on the methodology outlined in section 3.3. The project statuses are as of August 2022 when the most up-to-date vessel traffic data used to inform the baseline was collected. Additionally, although Forthwind was consented in 2016, an EIA Report for a new project design was submitted in May 2022 (Marine Scotland, 2022) following a scoping report in August 2021 and so this development is defined as scoped.

As per the methodology, any development greater than 50 nm from the Proposed Development array area is not considered.

Figure 14.1   Open ▸ presents the locations of the offshore wind farm developments screened into the cumulative risk assessment.

Figure 14.1 Offshore Wind Farms Developments Screened into Cumulative Risk Assessment

14.1.2    Oil and Gas Infrastructure

The only oil and gas infrastructure within 50 nm of the array site are seven wellheads, all of which are decommissioned, and therefore have no future influence of vessel movements. The closest surface oil and gas infrastructure is the BW Catcher FPSO at the Catcher Area Development, located approximately 73 nm to the east.

Therefore, no oil and gas infrastructure has been screened into the cumulative risk assessment.

14.1.3    Other Developments and Infrastructure

The Cambois connection is a potential secondary offshore export cable option for the Proposed Development which will connect at the southern extent of the Proposed Development array area and make landfall at Blyth on the UK east coast[9]. Given that this development will not include any surface infrastructure there is a limited pathway through which a hazard can be transmitted between the development and shipping and navigation users. Therefore, the Cambois connection is screened out of the cumulative risk assessment.

Other developments within 50 nm of the Proposed Development array area include the Inch Cape Met Mast (located approximately 8.3 nm to the west) and Energy Park Fife (located within the Firth of Forth). Both are existing developments and are therefore considered as part of the baseline.

There are no other known future developments (other than offshore wind farm developments) within 50 nm of the Proposed Development array area.

Therefore, no other developments or infrastructure has been screened into the cumulative risk assessment.

Table 14.1 Cumulative Screening

14.2   Cumulative Pre-Wind Farm Routeing

14.2 Cumulative Pre-Wind Farm Routeing

Figure 14.2   Open ▸ presents a plot of the main commercial routes within the Proposed Development array area shipping and navigation study area (full extent) alongside the screened in cumulative developments. Descriptions of the vessel traffic on each of the main commercial routes are provided in Table 11.1   Open ▸ .

Figure 14.2 Offshore Wind Farms Developments Screened into Cumulative Risk Assessment with Main Commercial Routes (Pre Wind Farm)

Table 14.2   Open ▸ summarises which main commercial routes interact with which cumulative developments (i.e. are defined as requiring a deviation due to the future presence of a cumulative development). As per the methodology for re-routeing due to the Proposed Development in isolation (see section 15.5.1), it has been assumed that any main commercial route within 1 nm of an offshore installation will require a deviation.

Table 14.2 Anticipated Cumulative Routeing Interaction with Cumulative Developments

In summary, three routes are anticipated to require a deviation due to the additional presence of Inch Cape (Scenario 1). There are no Scenario 2 developments and therefore no further deviations are considered noting that, as per the cumulative risk assessment methodology, Scenario 3 developments are considered only qualitatively and at a high level due to the limited information available.

15 Future Case Vessel Traffic

15 Future Case Vessel Traffic

This section presents the future case level of activity within and in proximity to the Proposed Development and the anticipated shift in the mean positions of the main commercial routes post wind farm.

The future case activity and routeing has been fed into the collision and allision risk modelling. The future case is considered throughout the risk assessment undertaken in volume 12, chapter 13 where future case refers to the assessment of risk based upon the predicted growth in future shipping densities and traffic types. The future case also refers to foreseeable changes in the marine environment, as discussed in the following subsections.

15.1   Increases in Commercial Vessel Activity

15.1 Increases in Commercial Vessel Activity

Forth Ports are the port operator for the major ports within the Forth including Grangemouth, Dundee, Leith and Rosyth. Given the influence of ports within the Firth of Forth and Firth of Tay in relation to vessel traffic movements within and in proximity to the Proposed Development, Forth Ports were consulted regarding future case traffic levels.

Forth Ports indicated that no terminal or berth changes are planned that may affect vessel traffic in the future with vessel numbers expected to remain reasonably consistent. Additionally, there are no commercial ferry routes planned. If anything, over the next five years any volume changes out of the Firth of Forth are likely to be decreases and beyond five years is difficult to forecast. At the Port of Dundee there is a lease for development relating to an offshore wind base.

The Scottish Whitefish Producers Association indicated that once Aberdeen South Harbour is operational there could be an increase in cruise traffic through the region.

In the longer-term, there may be increases in wind farm related traffic associated with the ScotWind developments north and east of the Proposed Development. This was raised during consultation, with the potential for terminals within the Forth to be used. However, given the low data confidence associated with these developments it is not possible to make any quantitative assumptions.

Given the uncertainty associated with long-term predictions of vessel traffic growth, as indicated by Forth Ports, two conservative and independent scenarios of potential growth in commercial vessel movements of 10% and 20% have been estimated throughout the lifetime of the Proposed Development. In reality, future case traffic growth is likely to fluctuate depending on seasonality and cargo and industry trends.

15.2   Increases in Commercial Fishing Vessel Activity

15.2 Increases in Commercial Fishing Vessel Activity

There is similar uncertainty associated with long-term predictions for commercial fishing vessel transits given the limited reliable information on future trends upon which any firm assumption can be made. Therefore, again to ensure a conservative approach, 10% and 20% growths in commercial fishing vessel movements have been estimated throughout the lifetime of the Proposed Development. Changes in commercial fishing activity are considered further in volume 2, chapter 12.

15.3   Increases in Recreational Vessel Activity

15.3 Increases in Recreational Vessel Activity

There are no known major developments which will increase the activity of recreational vessels in the region. As with commercial fishing vessels, given the limited reliable information on future trends, conservative 10% and 20% growths in recreational vessel movements have been estimated throughout the lifetime of the Proposed Development.

15.4   Increases in Traffic Associated with Project Operations

15.4 Increases in Traffic Associated with Project Operations

The anticipated number of vessels associated with the Proposed Development during the construction and operation and maintenance phases are presented in section 6.5.

15.5   Commercial Traffic Routeing (Project in Isolation)

15.5 Commercial Traffic Routeing (Project in Isolation)

15.5.1    Methodology

It is not possible to consider all potential alternative routeing options for commercial traffic and therefore alternatives have been considered where possible in consultation with operators. Assumptions for re-routeing include:

• All alternative routes maintain a minimum mean distance of 1 nm from offshore installations and existing offshore wind farm boundaries in line with industry experience. This distance is considered for shipping and navigation from a safety perspective as explained below; and
• All mean routes take into count sandbanks, aids to navigation and known routeing preferences.

Additionally, some routes which pass at a mean distance greater than 1 nm are sufficiently wide that there may be some interaction with the offshore wind farm boundaries (within the 90th percentile range). In such instances the width of the route has been reduced within reason and if required the mean position of the route has been shifted to a distance further from the offshore wind farm boundary to ensure there is no direct interaction.

Annex 1 of MGN 654 defines as methodology for assessing passing distance from offshore wind farm boundaries but states that it is “not a prescriptive tool but needs intelligent application”.

To date, internal and external studies undertaken by Anatec on behalf of the UK Government and individual clients show that vessels do pass consistently and safely within 1 nm of established offshore wind farms (including between distinct developments) and these distances vary depending upon the sea room available as well as the prevailing conditions. This evidence also demonstrates that the Mariner defines their own safe passing distance based upon the conditions and nature of the traffic at the time, but they are shown to frequently pass 1 nm off established developments.

Evidence also demonstrates that commercial vessels do not transit through arrays and this has been supported by feedback from Regular Operators during consultation (see 24 September 2021, 27 September 2021 and 1 October 2021 entries in Table 4.1   Open ▸ ).

The NRA also aims to establish the maximum design scenario based on navigational safety parameters, and when considering this the most conservative realistic scenario for vessel routeing is considered to be when main commercial routes pass 1 nm off developments. Evidence collected during numerous assessments at an industry level confirms that it is a safe and reasonable distance for vessels to pass; however, it is likely that a large number of vessels would instead choose to pass at a greater distance depending upon their own passage plan and the current conditions. One such example is Evergas, who have indicated during consultation (via charted passage plans) that they will pass further than 1 nm off the Proposed Development Array Area. This has been accounted for when establishing the main commercial route deviations (specifically for Route 14).

15.5.2    Main Commercial Route Deviations

An illustration of the anticipated worst case shift in the mean positions of the main commercial routes within the Proposed Development array area study area following the development of the Project is presented in Figure 15.1   Open ▸ . These deviations are based on Anatec’s assessment of the maximum design scenario including the outputs of consultation.

Figure 15.1 Anticipated Main Commercial Routes within Proposed Development Array Area Study Area (Post Wind Farm)

Deviations from the pre wind farm scenario would be required for seven out of the 14 main commercial routes identified, with the level of deviation varying between a 0.1 nm decrease for Route 4 and a 26.0 nm increase for Route 14. For the displaced routes, the increase in distance from the pre wind farm scenario is presented in Table 15.1   Open ▸ .

Table 15.1 Summary of Post Wind Farm Main Commercial Route Deviations within Study Area

In the case of Route 14, although the increase in route length is very high, since this is a transatlantic route the percentage change in the total route length is relatively low. Moreover, there will be large periods where vessels on this route are in open seas and should be able to make up any time losses incurred due to the deviations.

In the case of Route 11, although the deviation is negligible, the route does pass through the gap between the Proposed Development array area and Seagreen. This gap has variable width; at the western extent the minimum width is approximately 6.0 nm and at the eastern extent is approximately 2.8 nm. Usage of Route 11 is very low (an average of less than one vessel per day) and so the likelihood of an encounter between vessels is very low. Additionally, given the width of the gap there is sufficient sea room to allow a vessel navigating within to maintain a minimum distance of 1 nm from wind farm structures, minimising allision risk. Additionally, with the additional presence of Inch Cape immediately west of the gap, mariners are expected to choose a routeing option passing north of Inch Cape and Seagreen rather than utilise the gap (see section 15.6.6).

15.6   Commercial Traffic Routeing (Cumulative)

15.6 Commercial Traffic Routeing (Cumulative)

15.6.1    Methodology

Given the complex nature of the cumulative scenario (in terms of the influence of cumulative developments and number of affected main commercial routes), each of the leading routeing options is considered individually on a cumulative level. This allows full consideration of the various options available.

Consultation feedback with regards to likely vessel behaviour (see section 4.2) has been incorporated where appropriate including specific behaviour by vessel type and size.

This approach has been applied to the relevant cumulative risk assessment scenarios where a quantitative approach is required, i.e., Scenario 1 and Scenario 2 developments (see section 3.3), noting that no developments were screened into Scenario 2.

15.6.2    Main Commercial Routeing Between Forth Ports and Northern Ports

This subsection considers main commercial routeing between ports located within the Firth of Forth and UK ports located north of the Firth of Forth and Firth of Tay, such as Aberdeen and Invergordon. Figure 15.2   Open ▸ presents two example routes for the pre wind farm scenario together with the baseline, Scenario 1 and Scenario 2 developments.

The route passing south of NnG is Route 14 from section 11.2. The route passing north of NnG is not represented in the analysis of pre wind farm routeing for the Proposed Development in isolation since it is located outside the Proposed Development array area study area and is therefore not characterised by the vessel traffic survey data nor affected by the presence of the Proposed Development in isolation. However, from Anatec’s ShipRoutes database it is known that this coastal route, transited by an average of one vessel per day, exists and as discussed below vessels on this route are considered potential users of the navigation corridor between the Proposed Development array area and Inch Cape.

Figure 15.2 Examples of Pre Wind Farm Main Commercial Routes Between Forth Ports and Northern Ports

Based on Anatec’s ShipRoutes database, the majority of commercial vessels associated with the example routeing passing north of NnG are commercial vessels less than 150 m in length. Based on a review of the vessel traffic data, the vessels passing south on the associated routeing largely comprise tankers in the 100 to 200 m range.

With the presence of Scenario 1 developments (Inch Cape) in addition to baseline developments and the Proposed Development, a deviation will be required for north-south routeing out of the Firth of Forth which passes north of NnG. There are three clear options as illustrated in Figure 15.3   Open ▸ and detailed in the text that follows.

Figure 15.3 Cumulative Options for Main Commercial Routes Between Forth Ports and Northern Ports Passing North of NnG

• Pass inshore of Inch Cape (option A) – this option would involve vessels making a change in course to pass between Bell Rock and Inch Cape, resulting in a small deviation.
  • Vessels in transit on the relevant routes include commercial vessels; however charted water depths (30 to 40 m contours) could be considered suitable for such a deviation, noting the following factors that would make such navigation unsuitable for vessels carrying hazardous cargoes:
    • Proximity to shore and shallows;
    • Potential for failures; and
    • The approaches to the Firth of Tay and subsequent interaction with other vessel traffic.
  • The need for additional course adjustments and proximity to surface piercing features to both port and starboard result in this option increasing collision and allision risk for passing vessels.
  • This option would not be suitable for vessels that are not already passing Bell Rock at this proximity.
  • Forth Ports noted that they may also have to contact vessels asking for intentions if vessels shifted to this option (see section 4).
  • This option may increase encounters with recreational vessels, noting that it was raised during consultation (see section 4) that the presence of coastal fishing pots may displace recreational vessels into deviated commercial vessels.
• Utilise the navigation corridor between the Proposed Development array area and Inch Cape (option B) – this option would involve vessels passing closer to the northern boundary of NnG and then steering a course through the navigation corridor, resulting in a moderate deviation.
  • The proximity to surface piercing features to both port and starboard result in this option introducing increased collision and allision risk for passing vessels. However, the width and shape of the navigation corridor results in the number of additional course adjustments required being similar to the other options and the navigation corridor is MGN 654 compliant.
  • The presence of small craft operating within or in proximity to the navigation corridor may increase potential collision risk with commercial vessels (noting the associated routeing included large commercial vessels), noting this may discourage small craft from operating in proximity to the navigation corridor.
• Pass offshore of the Proposed Development array area (option C) – this option would involve vessels passing around the south and east of the Proposed Development array area, resulting in a very large deviation.
  • Vessels using this option would be more exposed to adverse weather given the greater distance from the UK east coast. However, there is sufficient available sea room to the south and east of the Proposed Development array area and Seagreen to ensure that a safe distance can be maintained from wind farm structures, and so collision and allision risk is considered to be low.

For north-south routeing out of the Firth of Forth which passes south of NnG, the available options are considered equivalent to those outlined above for north-south routeing out of the Firth of Forth which passes north of NnG, as illustrated in Figure 15.4   Open ▸ and detailed in the text that follows.

Figure 15.4 Cumulative Options for Main Commercial Routes Between Forth Ports and Northern Ports Passing South of NnG

• Pass inshore of Inch Cape (option A) – this option would involve vessels passing north of the Isle of May and inshore of Inch Cape, resulting in a large deviation.
  • This option is considered less feasible in this instance since passing north of the Isle of May requires navigating in shallower water where fishing pots are known to be present or making a sharp turn once beyond the two special marks located east of the Isle of May.
  • Vessels on this route include gas carriers with flammable cargoes that may not wish to use this route due to the potential for machinery failure closer to shore. Their own risk assessments (standing orders) may also prevent them passing closer to the shore.
  • From consultation with the RNLI, the increase in commercial vessel movements inshore of Inch Cape could increase the occurrence of incidents between Arbroath and Anstruther, especially in relation to leisure craft.
• Utilise the navigation corridor between the Proposed Development array area and Inch Cape (option B) – this option would involve vessels steering a course through the navigation corridor, resulting in a small deviation.
  • This option is considered more feasible in this instance since vessels will have better alignment with the navigation corridor after making a turn to port around NnG, with limited further course adjustments required.
  • The proximity to surface piercing features to both port and starboard result in this option introducing increased collision and allision risk for passing vessels. However, this may be mitigated by the navigation corridor being MGN 654 compliant.
  • The note on gas carriers for option A is again relevant here.
• Pass offshore of the Proposed Development array area (option C) – this option would involve vessels passing around the south and east of the Proposed Development array area resulting in a large deviation.
  • As per the equivalent option for north-south routeing out of the Firth of Forth, noting that a Regular Operator on this route indicated during consultation that their vessels would opt for this option given the navigational safety risks associated with the other options.

In summary, a safe deviation is available for vessels routeing between the Firth of Forth and northern ports. This can be achieved either by passing offshore of the Proposed Development array area or utilising the MGN 654 compliant navigation corridor. Although use of the navigation corridor will result in some increases in collision and allision risk, the size of the deviation associated with this routeing option is small compared with the very large deviation associated with passing offshore of the Proposed Development array area.

15.6.3    Main Commercial Routeing Between Forth Ports and Eastern Ports

This subsection considers main commercial routeing between ports located in the Firth of Forth and mainland European ports located in Norway and the Baltic region. Figure 15.5   Open ▸ presents two example routes for the pre wind farm scenario together with the baseline, Scenario 1 and Scenario 2 developments. These are based on Routes 5 and 10 from section 11.2.

Figure 15.5 Examples of Pre Wind Farm Main Commercial Routes Between Forth Ports and Eastern Ports

Based on a review of the vessel traffic data, the majority of commercial vessels associated with the example routeing are commercial vessels in the 100 to 200 m range. However, larger vessels are present including passenger vessels and tankers in excess of 200 m.

With the presence of Scenario 1 developments (Inch Cape) in addition to baseline developments and the Proposed Development, a deviation would be required for east-west routeing out of the Firth of Forth. There are three clear options as illustrated in Figure 15.6   Open ▸ and detailed in the text that follows. This figure also shows the worst case pre wind farm route.

Figure 15.6 Cumulative Options for Main Commercial Routes Between Forth Ports and Eastern Ports

• Pass inshore of Inch Cape (option A) – this option would involve vessels passing between Bell Rock and Inch Cape, resulting in a large deviation.
  • Water depths are suitable for such a deviation including for the large commercial vessels present.
  • Since these vessels do not currently pass in proximity to Bell Rock it is unlikely to be favoured by mariners.
  • Since this option passes in proximity to both Inch Cape and Seagreen there is also an increased collision and allision risk, which could increase due to the presence of coastal cruising routes for small craft.
• Utilise the navigation corridor between the Proposed Development array area and Inch Cape (option B) – this option would involve vessels passing around the south of NnG and then steering a course through the navigation corridor, resulting in a large deviation.
  • The proximity to surface piercing structures to both port and starboard result in this option introducing increased collision and allision risk for passing vessels. However, the width and shape of the navigation corridor results in the number of additional course adjustments required being similar to option A and the navigation corridor is MGN 654 compliant. However, this option is more complex to navigate than option C.
  • The presence of small craft operating within or in proximity to the navigation corridor may increase collision risk with commercial vessels (noting the associated routeing included large commercial vessels), noting this may discourage small craft from operating in proximity to the navigation corridor.
• Pass offshore of the Proposed Development array area (option C) – this option would involve vessels passing south of the Proposed Development array area, resulting in a large deviation.
  • Vessel schedules could be compromised, although given that the route heads into the open Northern and Central North Sea there is likely to be sufficient opportunity to make up time and soften the extent of the deviation.

In summary, a safe deviation is available for vessels routeing between the Firth of Forth and eastern ports. This can be achieved either by passing offshore of the Proposed Development array area or by utilising the MGN 654 compliant navigation corridor. Given that the size of the deviation associated with these options is similar, it is more likely that mariners will choose to pass offshore of the Proposed Development array area, noting that this option also minimises increases in collision and allision risk.

15.6.4    Main Commercial Routeing Between Forth Ports and Southern Ports

This subsection considers main commercial routeing between ports located within the Firth of Forth and European ports located in the Southern North Sea, such as Antwerp and Hamburg. Figure 15.7   Open ▸ presents two example routes for the pre wind farm scenario – both on a straight east/west course out of the Forth and passing south of the Proposed Development and NnG – together with the baseline, Scenario 1 and Scenario 2 developments. These are based on Routes 2 and 8 from section 11.2.

Figure 15.7 Examples of Pre Wind Farm Main Commercial Routes Between Forth Ports and Southern Ports

The majority of vessels on the associated example routeing were tankers. This included large tankers in excess of 300 m in length, however the majority were less than 200 m.

With the presence of Scenario 1 developments (Inch Cape) in addition to baseline developments and the Proposed Development there is not expected to be any deviation required for routeing out of the Forth and headed into the Southern North Sea, owing to the distance from Scenario 1 developments.

15.6.5    Main Commercial Routeing North–South Following UK East Coast

This subsection considers main commercial routeing between ports located on the UK east coast, such as Aberdeen and ports in the Humber. Figure 15.8   Open ▸ presents two example routes for the pre wind farm scenario – one on a relatively straight north-south course passing towards the eastern extent of the Proposed Development array area and one on a curved course following the UK east coast passing west of the Proposed Development array area and through Inch Cape – together with the baseline, Scenario 1 and Scenario 2 developments. These are based on Routes 1 and 4 from section 11.2, although also bear similarities to Routes 3 and 9.

Figure 15.8 Examples of Pre Wind Farm Main Commercial Routes North-South Following UK East Coast

The majority of vessels on the associated example routeing were commercial vessels of less than 100 m in length, however larger vessels were also present on the routeing further offshore.

With the presence of Scenario 1 developments (Inch Cape) in addition to baseline developments and the Proposed Development a deviation will be required for more westerly routeing. There are three clear options as illustrated in Figure 15.9   Open ▸ and detailed in the text that follows.

Figure 15.9 Cumulative Options for Main Commercial Routes North-South Following UK East Coast

• Pass inshore of the Proposed Development array area and Inch Cape (option A) – this option would involve vessels passing between Bell Rock and Inch Cape, resulting in a moderate deviation.
  • Water depths are suitable for such a deviation for the relevant vessels.
  • Since these vessels do not currently pass in proximity to Bell Rock it is unlikely to be favoured by mariners.
  • Since this option passes in proximity to both Inch Cape and Seagreen there is also an increased collision and allision risk, which could increase due to the presence of coastal cruising routes for small craft.
  • Forth Ports would have to contact vessels asking for intentions if vessels shifted to this option (see section 4.2).
  • This deviation may increase encounters with recreational vessels, noting that it was raised during consultation (see section 4.2) that the presence of coastal pots may ‘push’ recreational vessels into deviated commercial vessels.

• Utilise the navigation corridor between the Proposed Development array area and Inch Cape (option B) – this option would involve vessels steering a course through the navigation corridor, resulting in a small deviation.
  • The proximity to surface piercing features to both port and starboard result in this option introducing increased collision and allision risk for passing vessels. However, the width and shape of the navigation corridor results in the number of additional course adjustments required being similar to the pre wind farm route and the navigation corridor is MGN 654 compliant.
  • There is a risk for larger vessels utilising this option in adverse weather associated with under keel clearance from the shallow Marr Bank although given that the associated depths are similar to those navigated on the pre wind farm route the additional risks are considered minimal.
  • The presence of small craft operating within or in proximity to the navigation corridor may also increase collision risk with commercial vessels, which may discourage small craft from operating in proximity to the navigation corridor. However, during consultation it was indicated that recreational vessels operating a north-south transit may choose to navigate internally within the eastern portion of Inch Cape (depending on layout), thus avoiding the navigation corridor and reducing collision risk involving recreational vessels.
• Pass offshore of the Proposed Development array area (option C) – this option would involve vessels passing around the east of the Proposed Development array area, likely resulting in a decrease in the route length.
  • Vessels using this option would be more exposed to adverse weather given the greater distance from the UK east coast. Given the curved course of this route in the pre wind farm scenario, it is assumed that using the UK east coast as shelter is a key justification for the choice of longer passage and therefore use of this option would not be preferable.
  • This option would likely involve passing offshore of Kincardine, potentially increasing adverse weather exposure.

In summary, a safe deviation is available for vessels routeing north-south following the UK east coast. This can be achieved either by passing offshore of the Proposed Development array area or utilising the MGN 654 compliant navigation corridor. Given that the offshore option results in a shorter passage distance and minimises collision and allision risk it is more likely that mariners will choose to pass offshore of the Proposed Development array area in standard weather conditions, noting that this option also minimises increases in collision and allision risk. However, some vessels may prefer to utilise the navigation corridor given that this option retains a passage closer to the coast, particularly in adverse weather conditions.

For more easterly routeing in a north-south direction, there is not anticipated to be any deviation in addition to those anticipated for the Project in isolation scenario, owing to the distance from Inch Cape and the assumption that such vessels will make a small deviation east of the Proposed Development array area.

15.6.6    Main Commercial Routeing Between Dundee and Eastern Ports

This subsection considers main commercial routeing between Dundee and mainland European ports located in the Baltic region. Figure 15.10   Open ▸ presents an example route for the pre wind farm scenario passing north of the Proposed Development array area, together with the baseline, Scenario 1 and Scenario 2 developments. This is based on Route 11 from section 11.2.

Figure 15.10 Example of Pre Wind Farm Main Commercial Route Between Dundee and Eastern Ports

The majority of vessels on the associated example routeing were commercial vessels of less than 100 m in length, however larger vessels were also present.

With the presence of Scenario 1 developments (Inch Cape) in addition to baseline developments and the Proposed Development, a deviation would be required. There is one clear option as illustrated in Figure 15.11   Open ▸ and detailed in the text that follows.

Figure 15.11 Cumulative Options for Main Commercial Routes Between Dundee and Eastern Ports

• Pass north of Inch Cape and Seagreen – this option would involve vessels passing around Seagreen, resulting in a large deviation.
  • Water depths are suitable for such a deviation and there is sufficient available sea room west and north of Inch Cape to ensure a safe distance can be maintained from the wind farm structures. Therefore, collision and allision risk is considered to be low.
  • Additionally, Regular Operator consultation feedback from HAV Ship Management indicated that when considering the cumulative scenario there are no safety problems foreseen for their vessels – which operate on such a route out of Dundee – including in adverse weather conditions.

In summary, a safe deviation is available for vessels routeing between Dundee and eastern ports. This can be achieved by passing north of Inch Cape and Seagreen. Although a longer passage, this option minimises collision and allision risk and, once the route reaches the open Central North Sea, there is likely to be sufficient opportunity to make up time and soften the extent of the deviation.

16 Collision and Allision Risk Modelling

16 Collision and Allision Risk Modelling

16.1   Overview

16.1 Overview

To inform the risk assessment, a quantitative assessment of some of the major hazards associated with the Proposed Development has been undertaken. The following subsections outline the inputs and methodology used for the collision and allision risk modelling.

16.1.1    Scenarios Under Consideration

For each element of the quantitative assessment, both a pre and post wind farm scenarios with base and future case traffic levels have been considered. As a result, six distinct scenarios have been modelled:

• Pre wind farm with base case traffic levels;
• Pre wind farm future case with a 10% increase on base case traffic levels;
• Pre wind farm future case with a 20% increase on base case traffic levels;
• Post wind farm with base case traffic levels;
• Post wind farm future case with a 10% increase on base case traffic levels; and
• Post wind farm future case with a 20% increase on base case traffic levels.

The results of the base case scenarios are detailed in full in the following subsections, with the equivalent results for each future case scenario provided in section 16.4.

16.1.2    Hazards Under Consideration

Hazards considered in the quantitative assessment are as follows:

• Increased vessel to vessel collision risk;
• Increased powered vessel to structure allision risk;
• Increased drifting vessel to structure allision risk; and
• Increased fishing vessel to structure allision risk.

The pre wind farm assessment has been informed by the vessel traffic survey data (see section 10 and other baseline data sources (such as Anatec’s ShipRoutes database). Conservative assumptions have been made with regard to route deviations and future shipping growth over the lifetime of the Proposed Development.

16.1.3    Post Wind Farm Routeing

The methodology for the post wind farm routeing is outlined in section 15.5.1.

16.2   Pre Wind Farm Modelling

16.2 Pre Wind Farm Modelling

16.2.1    Vessel to Vessel Encounters

An assessment of current vessel to vessel encounters has been undertaken by replaying at high speed the vessel traffic data collected as part of the vessel traffic surveys (see section 5.2). The model defines an encounter as two vessels passing within 1 nm of each other within the same minute. This helps to illustrate where existing shipping congestion is highest and therefore where offshore developments, such as an offshore wind farm, could potentially increase congestion and therefore also increase the risk of encounters and collisions. No account of whether encounters are head on or stern to head are given; only close proximity is accounted for.

Figure 16.1   Open ▸ presents a heat map based upon the geographical distribution of vessel encounter tracks within a density grid. Following this, Figure 16.2   Open ▸ illustrates the daily number of encounters recorded within both the Proposed Development array area study area and the Proposed Development array area throughout the survey periods.

Figure 16.1 Vessel Encounters Heat Map within the Proposed Development Array Area Study Area (28 Days, August 2022 and January 2021)

Figure 16.2 Vessel Encounters per Day within the Proposed Development Array Area Study Area (28 Days, July 2020 & January 2021)

There was on average one encounter per day within the Proposed Development array area study area throughout the survey periods. The greatest number of encounters recorded in one day was four, on 23 January 2021, due to a number of cargo vessels and tankers transiting in the NW corner of the Proposed Development array area study area.

The most frequent vessel types involved in encounters within the Proposed Development array area study area were cargo vessels (31%) followed by tankers (28%) and commercial fishing vessels (19%).

16.2.2    Vessel to Vessel Collision Risk

Using the pre wind farm vessel routeing as input, Anatec’s COLLRISK model has been run to estimate the existing vessel to vessel collision risk within the Proposed Development array area study area. The route positions and widths are based on the vessel traffic survey data and have been validated using the long-term vessel traffic data and consultation with local stakeholders.

A heat map based upon the geographical distribution of collision risk within a density grid for the pre wind farm base case is presented in Figure 16.3   Open ▸ .

Figure 16.3 Pre Wind Farm Vessel to Vessel Collision Risk Heat Map within the Proposed Development Array Area Study Area

Assuming base case vessel traffic levels, the annual collision frequency pre wind farm was estimated to be 8.49×10-4, corresponding to a return period of approximately one in 1,178 years. This is slightly above the average for UK offshore wind farm developments and is reflective of the relatively large area covered. It is noted that the model is calibrated based upon major incident data at sea which allows for benchmarking but does not cover all incidents, such as minor effects. Other incident data, which includes minor incidents, is presented in section 9.

16.3   Post Wind Farm Modelling

16.3 Post Wind Farm Modelling

16.3.1    Simulated Automatic Identification System

Anatec’s AIS Simulator software was used to gain an insight into the potential re-routed commercial traffic following the installation of the wind farm structures within the Proposed Development array area. The AIS Simulator uses the mean positions of the main commercial routes identified within the Proposed Development array area study area and the anticipated shift post wind farm, together with the standard deviations and average number of vessels on each main commercial route to simulate tracks.

A plot of 28 days of simulated AIS (matching the total duration of the vessel traffic surveys) within the Proposed Development array area study area, based on the deviated main commercial routes, is presented in Figure 16.4   Open ▸ .

It is noted that the simulated AIS represents a maximum design scenario based on routes passing at a minimum mean distance of 1 nm from the Proposed Development array area.

Figure 16.4 Post Wind Farm Simulated Base Case AIS Tracks within the Proposed Development Array Area Study Area (28 Days)

16.3.2    Vessel to Vessel Collision Risk

Using the post wind farm routeing as input, Anatec’s COLLRISK model has been run to estimate the anticipated vessel to vessel collision risk within the Proposed Development array area study area.

A heat map based on the geographical distribution of collision risk within a density grid for post wind farm base case is presented in Figure 16.5   Open ▸ .

Figure 16.5 Post Wind Farm Vessel to Vessel Collision Risk Heat Map within the Proposed Development Array Area Study Area

Assuming base case traffic levels, the annual collision frequency post wind farm was estimated to be 9.69×10-4, corresponding to a return period of approximately one in 1,032 years. This represents a 15% increase in collision frequency compared to the pre wind farm base case result.

The increase in vessel to vessel collision risk was greatest along the southern and eastern edges of the Proposed Development array area. The change in vessel to vessel collision risk between the base case pre wind farm and post wind farm scenarios is presented in a heat map in Figure 16.6   Open ▸ .

Figure 16.6 Change in Vessel to Vessel Collision Risk within the Proposed Development Array Area Study Area

16.3.3    Powered Vessel to Structure Allision Risk

Based upon the vessel routeing identified within the Proposed Development array area study area, the anticipated re-routeing as a result of the presence of the Proposed Development, and the assumptions that relevant embedded mitigation measures are in place (see section 17), the frequency of an errant vessel under power deviating from its route to the extent that it may come into proximity with a wind farm structure associated with the Proposed Development is considered to be low.

From consultation with the shipping industry, it is also assumed that commercial vessels would be highly unlikely to navigate between wind farm structures due to the restricted sea room and will instead be directed by the aids to navigation located in the region and those present at the Proposed Development. During the construction and decommissioning phases this will primarily consist of the buoyed construction area, while during the operation and maintenance phase this will primarily consist of the lighting and marking of the wind farm structures themselves.

Using the post wind farm routeing as input, together with the maximum design scenario and local meteorological ocean data, Anatec’s COLLRISK model was run to estimate the likelihood of a commercial vessel alluding with one of the wind farm structures within the Proposed Development array area whilst under power. In order to maintain a maximum design scenario, the model did not consider one structure shielding another.

A plot of the annual powered allision frequency per structure for the base case is presented in Figure 16.7   Open ▸ , with the chart background removed to increase the visibility of those structures with lower allision frequencies.

Figure 16.7 Base Case Powered Allision Risk per Structure

Assuming base case vessel traffic levels, the annual powered allision frequency was estimated to be 1.52×10-4, corresponding to a collision return period of approximately one in 6,581 years.

The greatest powered vessel to structure allision risk was associated with structures along the western edge of the Proposed Development array area, where multiple main commercial routes pass at the minimum 1 nm distance. The greatest individual allision risk was associated with one of the structures on the western edge of the Proposed Development array area (approximately 2.72×10-5, or one in 36,701 years).

16.3.4    Drifting Vessel to Structure Allision Risk

Using the post wind farm routeing as input, together with the worst-case indicative array layout and meteorological ocean data, Anatec’s COLLRISK model was run to estimate the likelihood of a commercial vessel alluding with one of the wind farm structures within the Proposed Development array area. The model is based on the premise that propulsion on a vessel must fail before drifting will occur. The model takes account of the type and size of the vessel, the number of engines and the average time required to repair but does not consider navigational errors caused by human actions.

The exposure times for a drifting scenario are based upon the vessel hours spent within the Proposed Development array area study area. These have been estimated based on the vessel traffic levels, speeds, and revised routeing patterns. The exposure is divided by vessel type and size to ensure that these specific factors, which based upon analysis of historical incident data have been shown to influence incident rates, are taken into account for the modelling.

Using this information, the overall rate of mechanical failure in proximity to the Proposed Development array area was estimated. The probability of a vessel drifting towards a wind farm structure and drift speed are dependent on the prevailing wind, wave and tidal conditions at the time of the incident. Therefore, three drift scenarios were modelled, each using the meteorological ocean data provided in section 8.