ESNA Launches New Offshore Wind CTV Design

ESNA AS, a Norwegian company specializing in Surface Effect Ship (SES) design, has introduced its new vessel design – an air cushion catamaran for offshore wind crew transfer, called the Tern.

The crew transfer vessel (CTV) is partly supported by an air cushion in addition to the two side hulls.

The Tern uses the air cushion not only for motion damping during transit, but also to increase operational wave height at a wind farm. The vessel has a maximum service speed of above 40 knots in calm sea, it can have a draught of less than 1m, and can transfer personnel safely in sea states above 2m significant wave height.

“The Tern’s air cushion design offers a unique set of performances that matches very well with offshore windfarms’ requirements. Especially windfarms with medium distance from land, say between 25 and 50 nautical miles, benefit greatly from the high vessel speed. No other vessel type can offer the combination of high vessel speed, almost non-existent seasickness and such high operational wave height,” said Nere G. Skomedal, Naval Architect and Co-founder of ESNA AS.

“The Tern reduces the windfarms’ operational costs by providing significantly more efficient in-farm working hours per day due to less weather days, shorter transit time and less tidal and shallow water restrictions,” Skomedal explained.

ESNA (Espeland and Skomedal Naval Architects) introduced the Tern design only a few months after the company was officially launched as an independent ship design house that specializes on high-speed Surface Effect Ships (SES). It was founded by Nere G. Skomedal and Trygve H. Espeland, who have more than 25 years of extensive experience with design, construcion and operation of SES.

Trygve H. Espeland, Naval Architect and Co-founder of ESNA AS, said: “As a design office one of our main advantages is that we can tailor the vessel design to any shipyard, operator or windfarm owner’s requirements. The offshore windfarms have quite different requirements for speed, operational wave height, draught and payload. And with an average wind farm lifetime outperforming that of a service vessel, the O&M costs could be significantly reduced by tailoring the vessel design to the specific windfarm.

“Although the first Tern is designed to offshore windfarm service, the design can easily be adapted to other markets and the design can be scaled to meet even tougher environments. ESNA can also provide all the necessary SES expertise and equipment needed for efficient construction of SES at a shipyard.”

According to the company, the Tern is another example of advanced Norwegian ship technology now establishing a strong foothold in the offshore wind industry.

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Image: ESNA