First US Subsea Rock Installation Vessel Nears Inaugural Offshore Wind Assignment

Texas-headquartered Great Lakes Dredge & Dock Corporation (GLDD) has taken delivery of Acadia, the first US-flagged, Jones Act-compliant subsea rock installation vessel (SRIV).

GLDD ordered the vessel from Philly Shipyard, Inc. in 2021, with the first steel cut in July 2023 and the keel laid in May 2024. Acadia was then launched into the water of the Delaware River at the Hanwha Philly Shipyard in July 2025 and started sea trials this March.

“Taking delivery of Acadia represents a transformative moment for Great Lakes and underscores our dedication to installing and protecting domestic and international offshore energy infrastructure,” said Lasse Petterson, President and Chief Executive Officer of GLDD.

“This highly specialized vessel positions us at the forefront of subsea rock installation in the U.S. and international markets and enables us to play a critical role in major projects such as Empire Wind 1 and Sunrise Wind that offer a reliable, affordable, clean energy solution to the State of New York.”

The SRIV, of the S211 design by Ulstein, is capable of transporting and installing up to 20,000 tonnes of rock on the seabed, used as critical scour protection for subsea infrastructure such as power transmission cables, telecommunications cables, oil & gas pipelines, offshore wind turbine foundations, among other things.

With an overall length of 140.5 metres and a breadth of 34.1 metres, the vessel can accommodate 45 people.

Following delivery, Acadia will mobilise for Equinor’s Empire Wind 1 offshore wind project in New York, after which it is expected to proceed directly to Ørsted’s Sunrise Wind project, also located offshore New York.

After these two US projects, the vessel will mobilize to Europe to begin rock installation for a “major offshore wind developer”, staying busy for the majority of 2027, GLDD said.

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