This futuristic-looking windsail is the brainchild of Hugues De Turckheim and Philippe Marcovich...

The ACCWing is essentially a twin-skinned sail that can be raised or lowered.

It’s fully battened, can be reefed, and can change its section shape using its own internal muscles, operated by compressed air.

It achieves this with ‘muscles’ fitted at various positions up the sail on the inside of the wing.

The muscles consist of a braided line around flexible hoses, one on each side of the wing. When the hose contracts on one side, it pulls the sail into shape, creating a deeper camber.

Having muscles in different positions up along the sail means the section shape can change with height, allowing the twist to be controlled and developing a smooth transition from top to bottom.

The rotation of the masts changes the sail’s angle of attack.

When it comes to sheet loads, wingsails are often light. This is thanks to the sail’s balancing effect ahead of the mast, much like the equilibrium on a spade rudder.

It’s easy to imagine how this system could be totally automated to respond to wind speed and direction, both in section shape and with automated reefing.

While you might turn your nose up at letting a computer and servos take over the boat, there will surely be shipping companies that’ll sit up and take note. Since the clipper ships went out of fashion, there’s never been a need for them to put muscles and sails in the same sentence.

Until now.

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