VESSEL REVIEW | DC1 – Crest Wind's daughtercraft to support offshore renewables operations on US East Coast

Crest Wind, a joint venture formed by Crowley Maritime Corporation and Danish offshore vessel operator Esvagt, has taken delivery of a new crewboat/daughtercraft built by Derecktor Shipyards of Mamaroneck, New York.

DC1 was designed by UK-based naval architecture firm Chartwell Marine. She was built to US Coast Guard Subchapter T and L requirements and will support the activities of customers in the US offshore wind market.

The catamaran crewboat will provide safe and efficient transfers of personnel and equipment between service operation vessels (SOVs) and offshore wind turbines, even in challenging conditions.

Designed for challenging offshore conditions

“DC1 offers an adaptable platform capable of supporting a wide range of offshore and coastal missions,” Robin Saunders, Naval Architect at Chartwell Marine, told Baird Maritime. “[It is] a high-performance workboat that delivers stability, manoeuvrability, and practical functionality.”

Saunders said the owner required a US-built vessel capable of safely and efficiently supporting personnel transfers to and from an SOV in offshore environments. The crewboat needed to be able to maintain station alongside the SOV and operate reliably in challenging conditions, while meeting US Coast Guard Subchapter T certification requirements.

“The multihull offers superior seakeeping performance and increased stability to provide a comfortable, safe and workable platform for Siemens Gamesa’s operations and maintenance workforce. Daily duties will include personnel transfer, equipment movement, and supporting technicians conducting inspection, maintenance, and operational work.”

DC1 has a length of 40 feet (12 metres), a beam of 13 feet (four metres), a draught of just under two feet (0.6 metre), and space for two crewmembers and up to eight passengers. The design incorporates a very high bow freeboard, allowing the vessel to operate in higher sea states while mitigating tunnel slamming.

“This improves both the operability of the vessel and the comfort for those on board,” Saunders remarked. “It also increases the separation between the thruster and bow fender, greatly improving the vessel push-on ability compared to a similarly sized vessel with standard freeboard.”

The interior layout and crew comfort were also prioritised during the vessel’s development. Saunders explained that this would allow crew and personnel on board to focus on the task at hand without being negatively affected by environmental factors.

Improved comfort and station keeping

“Compared to a traditional daughtercraft, DC1 offers several features that create a safe and comfortable environment offshore. These include suspension seating that can be adjusted to crew preferences and sea conditions; large windows that enhance visibility and reduce motion-induced fatigue; and thermal and sound insulation that provide a climate-controlled, low-noise environment.”

The catamaran is powered by twin Volvo Penta IPS D6-500 systems, which deliver a combination of precise manoeuvrability, high thrust, and fuel efficiency. According to Saunders, this setup supports the vessel’s station-keeping needs when working alongside an SOV and provides the speed and responsiveness required for offshore personnel transfer.

Delivering required performance while addressing size constraints

In Saunders’ view, one of the key challenges that come with designing a vessel of this size is ensuring a high standard of comfort for both crew and passengers while delivering the performance required for offshore operations.

“Its layout and systems had to be tailored carefully to operator and end-use requirements without compromising on safety or functionality,” he told Baird Maritime.

“As with the wider design family [of daughtercraft], a core challenge is achieving crewboat-style performance within a much more compact footprint that meets operational requirements and the increasing demands of the offshore industry. This includes providing safe ‘push-on’ transfers, supporting rapid personnel movement, and remaining fully operable as an SOV-launched craft.”

Saunders explained that meeting these expectations required detailed optimisation of the hull form, fendering arrangements, and propulsion efficiency to ensure the vessel remains stable, predictable, and comfortable in challenging conditions.

“Weight management is another design consideration that applies across the platform. The vessel must remain within the strict limits of the SOV’s launch and recovery system while still incorporating the systems, structural strength, and capabilities required offshore. Achieving this demands close coordination between the designer and the builder to maintain tight weight control throughout the construction process.”

Saunders said that working with an experienced builder such as Derecktor allowed the kit set and construction methods to be refined and tailored to the preferred working practices of the vessel builder to ensure that the best vessel can be delivered to the client.