When Deepwater Wind set out to build America's first commercial offshore wind farm, no domestic manufacturer could supply the monopile foundations Europe had standardised on. European offshore wind contractors, meanwhile, were waiting to see whether a US market would materialise before committing resources of their own.

The answer engineers reached for wasn't a new foundation type — it was an old one, borrowed from a different industry entirely. Four-pile jacket foundations, developed for offshore oil and gas platforms, were adapted for wind turbines and built using expertise the US Gulf Coast already had in abundance.

30 MW
Total capacity
5
Turbines installed
400 t
First jacket weight
300 ft
Pile length, per corner
Phase 1 — Borrowing from oil and gas
A foundation type Europe wasn't using
With no US-manufactured monopile technology available, and European offshore wind contractors waiting on the sidelines, Keystone Engineering adapted a four-pile jacket foundation design directly from offshore oil and gas platform technology — a substructure type Gulf Coast fabricators already understood well.
Phase 2 — Fabrication in Louisiana
New industry, familiar fabricators
The jackets were fabricated by Gulf Island Fabrication in Louisiana, a company experienced with offshore oil and gas platforms but new to wind — bringing an existing domestic supply chain into an industry the US hadn't built one for yet.
Phase 3 — Steel in the water
The first jacket, and four more to follow
On 26 July 2015, the Weeks Marine and Manson Construction joint venture set the first 400-tonne steel jacket on the seafloor. Each jacket, semi-submerged with its topside rising 20 to 95 ft above the water, was secured with four 300-foot piles driven into its corners, then welded and grouted.
Phase 4 — Adapting to weather in real time
Bringing in reinforcements mid-schedule
Waves averaging over 3 ft challenged the project's floating rigs during pile driving. To keep the schedule intact, the team brought in an additional lift boat carrying a 500-tonne crane as a subcontractor — a vessel normally used to decommission offshore oil and gas platforms — to carry the majority of the pile-driving work through to completion.

No domestic monopile supply chain existed yet, so the industry didn't wait to build one — it borrowed a proven foundation type from offshore oil and gas instead.

Block Island Wind Farm became fully operational in December 2016, the first commercial offshore wind farm in the United States. As a reference case, it shows how an entire new industry segment got its start not through novel technology, but through the deliberate reuse of proven offshore engineering from an adjacent sector — jacket foundations, Gulf Coast fabrication, and marine installation expertise, all repurposed for wind.

For further reading on offshore wind foundation methods, see Offshore Wind Sector Hub

Related case studies: Horns Rev 1 · Vindeby · Borssele

Sources: Weeks Marine — installation contractor account of jacket transport, pile driving, welding and grouting; Manson Construction — joint-venture project record for the five 400-ton jacket foundations; Keystone Engineering — designer's account of the four-pile jacket substructures; Tethys (Pacific Northwest National Laboratory) — project status, capacity, foundation type and commercial-operation date.

Frequently Asked Questions

At the time of development, Europe had built many offshore wind farms predominantly using monopile foundations, but that manufacturing capability did not exist in the United States, and European firms were waiting to see how the US offshore wind industry developed before becoming engaged. Engineers instead adapted a four-pile jacket foundation design from offshore oil and gas platform technology, which US suppliers could fabricate.

The jacket foundations were designed by Keystone Engineering and fabricated by Gulf Island Fabrication in Louisiana, a company experienced with oil and gas platforms but new to wind. A joint venture between Weeks Marine and Manson Construction served as the offshore foundation installation contractor.

Each jacket was semi-submerged with its topside rising between 20 and 95 feet above the water, then secured with four 300-foot-long piles driven into the seabed at each corner, with the pile tops welded and grouted to complete the connection.

Waves averaging over 3 ft challenged the project's floating rigs during pile driving. To keep the schedule on track, the installation team brought in an additional lift boat carrying a 500-tonne crane as a subcontractor — a vessel normally used for decommissioning offshore oil and gas platforms — to support the majority of the pile-driving work.