WindServe Marine was an early adopter in the offshore wind sector. After three deliveries within the last year, its fleet of crew transfer vessels (CTVs) has grown to four with two more on the way.
The three 88.5-by-29.5-foot (27-by-9-meter) CTVs WindServe has added to the fleet are WindServe Genesis, WindServe Journey and WindServe Explorer. Each was designed by BMT and built by Senesco Shipyard, a sister company to WindServe. The three vessels are supporting multiple offshore wind projects off southern New England.
The 27-meter CTV series is powered by four 700-hp Volvo Penta D13 engines paired with Volvo Penta IPS 900 drives that also have a Volvo Penta dynamic positioning system. Electrical power comes from two 40-kW Kohler generators. Their top speed is around 27 knots, with an efficient cruise speed at 22 knots.
Josh Diedrich, WindServe’s managing director, spoke highly about the vessels’ power, maneuverability and safety. But he’s equally proud of the comforts available to technicians who ride the CTVs day after day to work on offshore wind farms.
“The biggest thing is the client is happy with it,” he said in a recent interview. “We definitely see they are very pleased with our service. These vessels have a very comfortable passenger area with lots of amenities. It’s comparable to first class seating on an airplane.”
CTVs are the maritime offshore wind equivalent of a utility player on a baseball team — they can do a little of everything. The primary job of a CTV is to carry technicians to and from offshore wind turbines. But they also have ample forward deck space to carry cargo and a Toimil knuckle-boom crane to hoist it onto the vessel from land. With tankage for 10,000 gallons of fuel, these vessels also can carry fuel as a cargo for other purposes during turbine construction.
During operations and maintenance of existing wind farms, these CTVs ferry people back and forth from shore. But they perform the same duty with a service operations vessel (SOV), which operates as a floating hotel and warehouse within the wind farm.
Once the CTV arrives at the turbine base with a technician, the vessel takes on a different role. It becomes a stable platform for the worker to embark or disembark from the turbine itself. For this to work, the bow of the CTV must push with at least half power and remain locked against the turbine base while the workers wearing a safety harness embark or disembark the vessel.
Resilient-mounted bow fenders on WindServe’s 27-meter CTVs supplied by RG Seasight cushion the approach into the tower base and help keep the bow locked against it.
Sufficient power and stability are critical for this maneuver, explained Capt. Lance Bishop from WindServe Explorer. But visibility is another. The wheelhouse is equipped with a massive front window that provides the operator with an excellent vantage point from which to oversee the deck hand and any activity involving the technicians.
“I can lean forward and see the tower and see almost the entire deck,” Bishop said.
WindServe built its first CTV, WindServe Odyssey, in 2020. The 64.7-by-23-foot vessel was designed to stay under 65 feet, where regulatory speed limits kick in to protect migrating right whales. That vessel is powered by four 800-hp Scania engines paired with HamiltonJet waterjets and can hit 30 knots in the right conditions.
Speed took a back seat to efficiency and a longer endurance in subsequent rounds of CTVs to hit the market since 2020. WindServe’s 27-meter series, for instance, has crew accommodations for six people and a crew galley/mess and four heads with two showers.
This is possible thanks to a much larger superstructure aft of the wheelhouse and passenger cabin and six additional feet of width at the beam. Ample fuel tanks also give the crew flexibility to stay on station for days at a time, and a watermaker ensures a steady supply of fresh water.
“We’re basically only limited by the amount of food we can carry,” Bishop said.
Holding station against the turbine base, occasionally in 4- or 5-foot seas, requires plenty of power. But these CTVs also must be maneuverable and quick to ensure a smooth connection against the turbine base.
“These are pretty nimble boats,” Bishop said during a vessel tour in Rhode Island. “We can walk this boat straight sideways. They handle very well in tight quarters. And as far as getting onto the tower base, it has very quick responsiveness and when it makes good contact with the base it holds onto it.”
The passenger cabin is located forward on the main deck. It is outfitted with 24 shock-absorbing seats each with four-point harnesses for wind farm technicians. There is a dedicated space for crews to place their gear, a refreshment center and two TVs installed forward with a DirecTV package. The vessel also has a Starlink satellite internet connection that allows for video conferencing and other operations that require reliable wireless service.
The wheelhouse is equipped primarily with Furuno navigation electronics and a Simrad autopilot. Off-ship communication can be done in many ways, including Sailor VHF radios, Starlink or via email or video call from a computer aft in the wheelhouse.
Senesco Marine expects to deliver two additional 95-foot CTVs for WindServe by the end of the year. The extra length creates space in the forward hulls to install batteries at some future date to reduce emissions while underway or loitering at the wind farm. The term for vessels like this is “hybrid ready.”
Ted Williams, president of the North Kingstown, R.I., shipyard, said the multi-vessel CTV project starting with WindServe Odyssey presented a challenge for a yard that until then had primarily specialized in steel-hulled vessels.
Although steel welding can take place in most conditions without issue, welding aluminum requires very clean, climate-controlled spaces to prevent issues with the welds. The shipyard developed a team of highly skilled welders through construction of these CTVs.
“I am most proud of leading the United States in building this type of vessel,” he said in an interview. “I don’t think anyone has built as many as we have. We have developed quite a capable team that is able to do this. It has been a good challenge and a good journey and we continue to suceed.”
And so have these new CTVs, as they bolster WindServe’s capabilities in the offshore wind industry that continues to expand and create new opportunities for mariners and operators. •