Specialist aluminium boatbuilder, Aluminium Marine Consultants (AMC), and Norway’s Espeland and Skomedal Naval Architects (ESNA) have entered a collaboration under which AMC added ESNA’s surface effect ship (SES) design to its portfolio.
Rob Stewart , commercial director, AMC, said: “This vessel is unique in the qualities that it offers and we’re very excited to work with ESNA. This new design will enhance the AMC portfolio and help innovate the crew transfer vessel market.”
The new ESNA Tern SES crew transfer vessel offers turbine access in up to 2.5m significant wave height, with a maximum speed above 40 knots and greatly reduced speed loss in high seas, the company said.
The vessel’s tern hull consists of two slender catamaran hulls with the area between the hulls closed with flexible reinforced rubber fingers in the bow and an inflated rubber bag in the stern.
This allows centrifugal fans blow air into the enclosed space, providing an air cushion that lifts up to 80% of the vessel weight. The vessel can be lifted up and down approximately two metres, which means it is able to cancel up to the same height of vessel motion in waves. This is especially effective in long waves/swell, where all other vessel types will float and follow the wave surface, the company explained.
The remaining 20% of the vessel’s weight is supported by side hull buoyancy which allows for high vessel speed because frictional resistance is decreased.
The Tern is equipped with a computer controlled active motion damping system which reduces vertical motions both at high and low vessel speeds reducing seasickness. As the lift fans supply air to the air cushion, the control system actively controls vent valves that either ventilate the air cushion to a low pressure or closes the valves so that the air cushion pressure is increased.