First US subsea rock installation vessel begins sea trials

March 18, 2026, by Nadja Skopljak

Acadia, the first U.S.-flagged, Jones Act-compliant subsea rock installation vessel (SRIV), owned by Texas-headquartered Great Lakes Dredge & Dock Corporation (GLDD), has begun its sea trials, with operations to start soon.

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 on July 16, 2025.

The SRIV, of the S211 design by Ulstein, is capable of transporting and installing up to 20,000 metric tons 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 meters and a breadth of 34.1 meters, the vessel can accommodate 45 people.

Upon completion scheduled for the first quarter of 2026, Acadia is expected to begin operations immediately thereafter, first on Equinor’s Empire Wind 1 offshore wind farm and then on Ørsted’s Sunrise Wind project.