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ACADIA

GLDD’s Critical Role in Realizing Offshore Energy’s Potential

Subsea rock installation is the most effective means of providing long-term scour protection. With the first and only Jones Act–compliant subsea rock installation vessel built at the Hanwha Philly Shipyard in Philadelphia, GLDD is helping to strengthen the foundations for U.S. offshore energy.

Among its leading-edge technologies to better protect the environment, the vessel has EPA Tier 4–compliant engines, a battery energy storage system to shave peak loads, and plug-in capability to obtain shore power while loading. Additionally, it will be able to run on biofuel, reducing the ship’s CO2, SOx, and overall hydrocarbon footprint, and will be equipped with active emissions control technology to mitigate NOx emissions.

Acadia specification:

Main dimensions of the vessel are:

Loa 140.5 m / 461 ft
Lpp 134.9 m / 442 ft
Beam (moulded) 34.1 m / 112 ft
Depth (main deck) 10.7 m / 35 ft
Draught (operational) 7.0 m / 23 ft
Service speed 12 kn
Installed power 2 x 3,150 kW – 2 x 2,250 kW
Propulsion thrusters 2 x 2,500 kW
Retractable thruster 2 x 1,200 kW
Tunnel thrusters (fwd) 2 x 900 kW
Positioning system DP 2
Class ABS
Rock hold capacity 20,000 t
Complement 45 P

Offshore Energy Projects

Empire Wind 1

Great Lakes Dredge & Dock Company, in joint venture with Van Oord, is supporting Empire Wind 1—an 810 MW offshore wind farm off New York that will power approximately 700,000 homes.

Under a 2022 agreement, the joint venture has executed rock installation activities, mobilizing the subsea rock installation vessels Nordness and Bravenes to place approximately 291,000 metric tons of rock to protect critical subsea infrastructure.

Work remains ongoing, with GLDD’s subsea rock installation vessel Acadia set to perform additional precision rock placement as the project advances.

Through this partnership, GLDD and Van Oord are helping advance clean, reliable energy in the U.S.

South Brooklyn Marine Terminal, NY (SBMT)

Empire Wind 1 Export Cable Rock Protection at South Brooklyn Marine Terminal

Great Lakes Dredge & Dock Company supported the Empire Wind 1 offshore wind development by completing critical export cable protection work at the South Brooklyn Marine Terminal (SBMT), helping safeguard the cables that will carry clean energy from the wind farm back to New York.

Empire Wind 1 is expected to deliver renewable energy to approximately 700,000 households, making the export cable system a vital link between offshore generation and onshore power distribution. The export cables were installed in a pre-dredged trench along the SBMT approach and landing area. GLDD’s scope focused on stabilizing and protecting the cables by placing a precisely engineered two-layer rock system.

The first layer, known as Cable Top, was installed directly over and around the cable to provide foundational protection and support. A second layer, Cover Stone, was then placed to provide long-term armoring and resistance to currents, vessel activity, and seabed movement. At the slope landing area, where the export cables transition and are exposed to increased hydraulic forces, GLDD installed an additional armor rock layer on top of the standard two-layer system, delivering enhanced protection in the most vulnerable section of the alignment.

In total, GLDD installed 47,889 metric tons of rock to meet the project’s design requirements. In addition to cable protection, GLDD performed restoration work in the southeast corner of the project footprint, where a designated tidal restoration area required the seabed to be returned to its original condition. This restoration was completed by rebuilding a mound using cover stone, chock stone, and a sand cap, designed to mimic the surrounding seabed and reinstate the area as it existed prior to dredging.

GLDD executed the work between May and October using Carver’s 2000 HP tending tug and the highly capable Carver 2000 Series E-Crane, operating from a spudded barge. This equipment package provided the stability and placement control required for accurate rock installation in a confined marine terminal environment.

Through careful placement, engineered layering, and environmental restoration, GLDD helped ensure Empire Wind 1’s export cables are protected for long-term service, supporting the delivery of renewable offshore wind energy to New York.

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GLDD’s Critical Role in Realizing Offshore Energy’s Potential

Acadia specification:

Empire Wind 1

South Brooklyn Marine Terminal, NY (SBMT)