SSE Renewables has selected Seaway7 as preferred supplier for the offshore turbine foundations and inter-array cables at Berwick Bank B, a proposed 1.4GW wind development off the Scottish Borders. The engineering, procurement, construction and installation package remains conditional on the award of a final contract and SSE’s investment decision.
The arrangement, announced on 20 October, concerns around 90 fixed-bottom turbine foundations and their associated subsea connections. Seaway7, part of the Subsea7 group and based in Aberdeen, would oversee design, supply and installation across a site approximately 38km from the Scottish Borders coastline. The project is one phase of SSE’s wider Berwick Bank development, which has potential capacity of up to 4.1GW.
Water depths across the proposed site average 52 metres and reach approximately 59.7 metres. SSE says that, if delivered as planned, Berwick Bank B would be the world’s deepest fixed-bottom offshore wind farm. Such depths influence foundation geometry, installation vessel capabilities, lifting procedures and the tolerances achievable when positioning heavy structures on the seabed, although the final foundation design and installation methodology remain subject to project engineering.
A fixed-bottom foundation must transfer static turbine loads and cyclic forces from wind and waves into the seabed while maintaining the tower’s position and integrity. The 90 planned foundations therefore require site-specific assessment of soils, load cases and installation tolerances. SSE has not published the precise foundation type for every turbine position or a complete geotechnical design package in the preferred supplier disclosure.
Inter-array cables would connect individual turbines into the offshore collection network. Route design, laying and burial or other protection must take account of seabed conditions and interactions with marine activity. Damage at a cable joint or along an unprotected span can interrupt transmission from functioning turbines, making installation quality and subsequent inspection part of the project’s operational planning.
Seaway7 expects to deploy the Seaway Alfa Lift, Seaway Strashnov and Seaway Phoenix installation vessels on the campaign. SSE has set out a provisional sequence in which preparatory offshore construction work could begin in 2028, with foundation and inter-array cable installation starting in 2029 and concluding in 2031. Those dates depend on the project receiving its final investment approval, currently expected in late 2027.
SSE estimates that the preferred supplier agreement would create or support 465 UK jobs, including 400 in Scotland. Its breakdown comprises about 160 direct roles with Seaway7, 105 indirect roles in the UK supply chain, and another 200 direct and indirect positions linked to foundation marshalling at a Scottish port. The port is still to be selected and the job figures remain projections tied to a project awaiting final approval.
The projected employment combines newly created posts and existing or project-based roles that the work could sustain. Marshalling would involve receiving, inspecting and staging heavy foundations, arranging storage and lifting operations, and feeding components to offshore installation vessels in the required sequence. Quayside load capacity, transport interfaces and berth access will influence the selection of the Scottish port.
Through its Berwick Bank B commitments so far, SSE now expects around 600 roles to be created or supported across the UK, including more than 500 in Scotland. The cumulative figures include the separately proposed operations and maintenance base at Montrose Port, associated with around 100 long-term jobs and 30 construction positions. Those roles should not be counted again as additional employment arising solely from the Seaway7 agreement.
Seaway7 and SSE have worked together on the Beatrice and Seagreen offshore wind projects, while Seaway7 has also been involved in installation work at Dogger Bank. Previous projects provide experience of vessel scheduling, heavy offshore lifting, interface management and complex installation sequences, although each site’s geology, metocean conditions and turbine configuration require new engineering assessments.
The wider Berwick Bank development received consent in July 2025. Berwick Bank B subsequently secured a Contract for Difference lasting 20 years under Allocation Round 7, which provides a route to contracted electricity revenue but does not amount to approval to invest in construction. SSE expects its final investment decision in late 2027, with the preferred supplier arrangement still subject to final contract award.
At full planned capacity, SSE estimates that the wider 4.1GW Berwick Bank project could generate enough electricity annually to match the consumption of about 6.5 million UK homes. That comparison refers to the entire development rather than the 1.4GW B phase alone and is based on projected output assumptions, not measured generation.
SSE’s next commercial milestones are a definitive Seaway7 contract, the foundation marshalling port selection and the project’s final investment decision. Only after those approvals can the planned deployment of vessels, supported employment and 2029–31 installation programme become firm delivery commitments.
