THE TURBOSAIL
EXPLAINED.

Both systems seek useful propulsive force from the wind, but they do not work in the same way. A Flettner rotor continuously spins a cylinder and develops lift through the Magnus effect. The Cousteau Turbosail used a largely fixed aerodynamic profile, active aspiration and a movable control flap.

The 1985 technical record places Jacques-Yves Cousteau, Lucien Malavard and Bertrand Charrier within a wider Cousteau Foundation and Pechiney development program supported by engineers and researchers. The work progressed from theoretical development and wind-tunnel testing toward a marine installation at meaningful scale.

Moulin à Vent provided the full-scale experimental vessel needed to determine whether the concept could function outside the laboratory—in variable wind, sea and operating conditions, and alongside conventional propulsion.

Bureau Mauric's later retrospective identifies Moulin à Vent as the prototype Turbosail boat and dates the experimental conversion to 1982. The 1985 technical record describes trials at Étang de Berre near Marseille and subsequent operation in the Mediterranean.

Those 1982–1983 trials moved the Turbovoile from controlled research toward sustained marine use and the 1983 Atlantic experiment. Moulin à Vent is historically important because the catamaran was not merely carrying the system: she was the full-scale platform through which it was tested at sea.

At sea, the installation had to operate through changing wind angles, vessel motion and structural loads while working in combination with engine propulsion. This was the difference between validating an aerodynamic idea under controlled conditions and learning how an experimental system behaved over prolonged marine operation.

Contemporary reporting records severe Atlantic weather during the 1983 passage and the eventual loss of the experimental mast and Turbosail installation. That loss describes the failure of that prototype installation; it does not establish that the aerodynamic concept itself ended there. The wider Turbosail program continued afterward.

Moulin à Vent was the full-scale experimental platform. Alcyone, launched in 1985, was the purpose-built expedition vessel that carried the evolved system into sustained service.

Alcyone combined twin Turbosails with engine propulsion aboard a ship designed around exploration, science and filmmaking. The transition from one vessel to the other makes Moulin à Vent an essential part of the record: the prototype through which the idea met the sea before its operational application travelled farther.