Rest assured there is nothing supernatural happening here.

What Damen proposes is a vessel designed to provide onsite work facilities and accommodation for 45 maintenance personnel plus 15 crew for voyages up to one month long.

"There is a growing trend for wind turbines to be located further from shore," Damen offshore wind business development manager Peter Robert said.

"At distances greater than 30 nautical miles, maintenance crew transfer from shore within one day becomes impractical and costly."

The dynamically positioned wind farm service vessel will have a telescopic, motion-compensated gangway.

It will let each three-man maintenance team walk quickly and safely between vessel and turbine.

"When we sought market views on a larger support vessel, customers set us an 80% availability target for maintenance crew transfer in wave heights up to 3m," Robert said.

"At the same time the vessel needed exceptional levels of comfort because turbine engineers often have a land-based background and staff retention is an issue."

The result is a monohull vessel with its bridge and accommodation located amidships.

With a 90m length overall and a 20m beam the Damen WSV will have 500 cubic metres of deck space, a helideck and a motion and heave compensating crane.

Its 4.6m draft will allow for comfort while also conferring power savings.

Special attention has been paid to the interiors and onboard service space layout.

Public spaces have been mapped for efficient workflows and storage, while 60 single occupancy cabins, a fitness centre and internet and movie services will benefit life at sea.

The vessel is designed to drop off all seven of its three-person maintenance crews within three hours and then remain within range to provide support and emergency assistance through the day before pick-up.

Robert said the Damen WSV would adhere to the company's "E3" commitment to deliver vessels that are environmentally friendly, efficient in operation and economically viable.

To this end, the main propulsion system will be diesel-electric.

"This vessel has been designed to meet our aims of serving the needs of the planet, the people working and living on it and those of the owner to make a healthy profit," Robert said.

He said the vessel was also attracting interest from the oil and gas sector.