Berwick Bank B: Seaway7's Preferred-Supplier Nod Puts 90 Foundations — and a 60-Metre Water-Depth Record — on the 2027 FID Clock

SSE Renewables has named Seaway7 preferred supplier for the engineering, procurement, construction and installation (EPCI) of turbine foundations and inter-array cables at Berwick Bank B, the 1.4 GW second phase of its 4.1 GW Firth of Forth development. The agreement is conditional on a final contract award and on SSE taking a final investment decision, which the company expects in late 2027.

The headline number circulating is employment: 465 UK jobs supported, 400 of them in Scotland, of which around 160 are direct roles with Seaway7 led from its Aberdeen base and 105 sit in the UK supply chain, with a further 200 tied to foundation marshalling at a Scottish port still to be named.

For the fabrication and steel supply chain, however, the more consequential details are buried in the technical scope: around 90 fixed-bottom foundations, average water depth of 52 m and a maximum of 59.7 m, with installation scheduled for 2029–2031 and preparatory offshore works possibly starting in 2028. That is a demanding structural brief, and its timing matters more than its present contractual status.

A preferred-supplier agreement is a schedule signal, not a contract

It is worth being precise about what has and has not happened. No contract value has been disclosed. SSE has not confirmed whether the arrangement is exclusive. Foundation type — monopile or jacket — has not been specified publicly. The steel tonnage therefore cannot be stated as fact, only modelled.

What the announcement does establish is an intent to procure on a known timetable. SSE's own framing — that this would be the third EPCI contract between the two companies after Beatrice and Seagreen, alongside Seaway7's current turbine installation work at Dogger Bank — indicates an incumbent-led, repeat-supplier strategy rather than a competitive re-tender. For a project of this water depth, that is rational: the installation methodology, vessel selection and geotechnical risk profile are the hard parts, and Seaway7 has already executed in comparable Scottish conditions.

The named vessels — Seaway Alfa Lift, Seaway Strashnov and Seaway Phoenix — are consistent with a large-monopile or jacket campaign requiring heavy-lift and specialised foundation-installation capability. The inclusion of Alfa Lift, a dedicated foundation-installation vessel, is the clearest available hint that the campaign is being planned around large, single-piece foundations rather than a component-assembly approach.

Why 59.7 metres is the number that matters

Water depth drives foundation mass, steel grade, wall thickness, weld complexity and installation vessel requirements more than almost any other variable. At an average of 52 m and a maximum just under 60 m, Berwick Bank B sits at the deep end of the fixed-bottom envelope — SSE states it would become the world's deepest fixed-bottom offshore wind farm on completion, a claim that will be tested against Seagreen (around 58 m) and other deep-water projects but is not implausible given the stated maximum.

Deep water pushes designers toward either very large monopiles with thick walls and heavy transition pieces, or jackets with higher fabrication labour content. Either route is steel-intensive per megawatt. My estimate, using typical industry rule-of-thumb masses for 12–15 MW-class hardware, is that ~90 foundations imply roughly 160,000–270,000 t of structural steel if monopile-based, and potentially more if jacket-based given higher unit mass per foundation. That range is an analytical estimate, not a reported figure, and should be treated as an order-of-magnitude planning input rather than a procurement forecast.

The turbine count implied by the foundation number is consistent with roughly 90–95 units at 15 MW class — arithmetic that aligns with the ~90 foundations SSE cites and suggests the project is being designed around current-generation large turbines rather than a smaller, higher-count array.

The procurement clock is tighter than the FID date suggests

A late-2027 FID with installation in 2029–2031 implies foundation fabrication must begin almost immediately after sanction. Monopile and jacket lead times of 12–24 months are normal, which places steel plate and section procurement in roughly 2027–2029 — overlapping the FID decision rather than following it comfortably.

This has two practical consequences. First, fabricators hoping to participate need to be engaged during 2027, before contract award, or they will miss the window. Second, the unresolved marshalling port is not a minor logistical detail: it determines load-out logistics, quay capacity and heavy-transport routing, and its announcement will be a meaningful signal for whichever Scottish port secures it. Trade coverage has used imagery of Seaway Alfa Lift at Invergordon, but SSE has explicitly said the port will be announced in due course — Invergordon should not be treated as confirmed.

Inter-array cable scope is smaller in steel terms but relevant to the non-ferrous and armouring supply chains. Estimated volumes for a 1.4 GW array at 66 kV are in the range of 250–450 km of cable, implying substantial copper or aluminium conductor demand plus lead sheathing and steel wire armour. Those are different suppliers from the plate mills, and worth tracking separately.

Jobs arithmetic and the political economy of the award

The employment figures deserve a note of caution. Of the 465 UK jobs cited, only around 160 are direct Seaway7 roles; 105 are supply-chain indirect; and 200 depend on a marshalling port decision that has not been made. SSE's cumulative Berwick Bank B figure of roughly 600 UK jobs, more than 500 in Scotland, includes 100 long-term and around 30 construction roles at the Montrose Port operations and maintenance base.

These are legitimate commitments, but they are projections contingent on FID, port selection and final contract award. Presenting them as achieved outcomes would overstate the position; presenting them as aspiration would understate the seriousness of the preparatory work SSE has already done. The honest reading is that they are conditional planning assumptions backed by a secured CfD — which is a stronger footing than most pre-FID projects enjoy.

The CfD is the decisive commercial fact here. A 20-year contract awarded in Allocation Round 7 in January 2026 removes the revenue-certainty obstacle that has stalled other UK projects. The remaining risks are cost-side: fabrication capacity, vessel availability and the depth-driven engineering challenge.

What to watch

• Foundation type disclosure. Monopile versus jacket changes the steel tonnage, the fabricator shortlist and the welding labour profile. This is the single most useful piece of information still missing.
• Port announcement. The marshalling decision will indicate which Scottish fabrication and logistics cluster benefits, and whether any domestic content is achievable.
• Final contract award timing. A preferred-supplier status that persists into 2027 without conversion would be a warning sign on FID readiness.
• CfD strike price. Not established in the available material; it determines the project's cost tolerance and therefore its willingness to pay for European rather than Asian fabrication.

Berwick Bank B is, on the evidence available, a well-sequenced project: consent secured, revenue support secured, installation contractor effectively selected, O&M base chosen. The gap between preferred supplier and contract is real, but it is a gap of timing rather than of intent — and for the foundation fabrication supply chain, the clock starts well before the FID is signed.

Note on sourcing: job figures, foundation count, water depths, vessel names, installation window and CfD/consent dates are as reported by SSE and OffshoreWIND.biz. Steel tonnage and cable length ranges are the author's estimates based on typical industry parameters and are not reported project figures. Contract value, exclusivity, foundation type and CfD strike price were not available in the sources reviewed.