A design contract has been awarded for the first US-flagged Jones Act compliant subsea rock installation vessel, to serve the US offshore wind industry.

inclined fallpipe vessel

The inclined fallpipe vessel will primarily install protective layers of rock at offshore wind turbine foundations. Photo: Ulstein

Great Lakes Dredge & Dock Co. LLC (GLDD) has contracted Ulstein Design & Solutions BV to design the inclined fallpipe vessel for subsea rock installation. The vessel is considered to be critical in building the future of the US offshore wind industry, including establishing a US-based rock supply chain network.

The Basic Design will be developed by Ulstein’s Dutch design office, with strong engineering contributions from its sister offices in Norway and Poland.

“We are extremely proud that GLDD has entrusted us to develop their new asset,” said Edwin van Leeuwen, managing director at Ulstein’s Dutch design office.

Rock installation

The vessel will primarily install protective layers of rock at offshore wind turbine foundations by means of an inclined fall pipe system. Its large and strong aft deck area makes the vessel a highly flexible asset, enabling specialised subsea operations.

“At the start of the design we applied our newly developed ‘Blended Design’ method, enabling GLDD to co-evolve their business case with the ship concept. This resulted in significant gains in economic performance, at the same time reducing fuel consumption and emissions, by optimising vessel main dimensions, speed and dynamic positioning capability,” explained Ko Stroo, Ulstein’s lead naval architect and project manager. “Our design for this US Coast Guard compliant vessel strongly focused on Jones Act compliant shipbuilding in the USA and ease of construction.”

By Rebecca Jeffrey