America’s First Jones Act Rock Installation Ship Can Place 20,000 Metric Tons Of Rock On The Seabed

Great Lakes Dredge & Dock Corporation (GLDD) has taken delivery of the Acadia from Hanwha Philly Shipyard in Philadelphia, which is the first U.S.-flagged, Jones Act-compliant subsea rock installation vessel (SRIV).

The order for this vessel was placed in 2021, with the first steel cutting done in 2023, followed by keel laying in 2024. The vessel was then launched into the Delaware River in 2025, and it completed its sea trials in 2026.

The project supported the domestic supply chain as it used steel sourced from Ohio and generated high-paying jobs for labourers across Texas, Louisiana, Pennsylvania and New Jersey.

The Acadia has an S211 design by Ulstein Design and Solutions BV. It is 140.5 m long, 34.1 m wide and can accommodate 45 personnel.

It is bio-fuel ready and has battery and shore power capabilities for when it is berthed. The vessel operates with a DP-2 dynamic positioning system that ensures accuracy in water depths of up to 65 m.

It uses an inclined fall pipe system to transport and install up to 20,000 metric tonnes of rock onto the seabed. This rock, which is put in place with precision, offers protection to subsea infrastructure like communication cables or oil and gas pipelines, offshore wind turbine foundations from strong currents, other ships’ anchors or wave erosion.

“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 specialised 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”.

After its delivery, the Acadia will sail to New York to support Equinor’s Empire Wind 1 offshore wind project, after which it will proceed to Ørsted’s Sunrise Wind project, which is also located in New York.

After completing these two domestic contracts, GLDD plans to pivot the vessel’s operations to international waters. The Acadia will head to the Atlantic and then Europe to begin rock installation for a major international offshore wind developer, a robust contract expected to keep the specialised vessel busy for the majority of 2027.