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VIDEO: Boating on air power

Plain is probably an appropriate term for the M65, with its angular deckhouse, small windows and conspicuous air intake grilles on each side of the bow, as the white 65-footer sits at a dock at Antalya on Turkey's southern coast.

Click play to watch the M65 under way. Mobile users can click here.

But looks don't matter to an air-supported vessel, which blows bubbles out the stern as it rises on a cushion of air, reducing the friction between hull and water and allowing the boat to go faster and farther on less fuel and horsepower. Such qualities get attention these days because they save money and are easier on the environment. Traditional planing hulls need plenty of horsepower because they push lots of water out of the way as they get on plane and up to speed.

"We have scientifically documented fuel savings of 50 percent, compared with the leading European and U.S. brands in the 50- to 70-foot range," says Ulf Tudem, the general manager of Effect Ships International AS in Sandefjord, Norway.

The cushion of compressed air under the hull lifts the boat in the water and reduces performance-robbing drag. One collateral benefit of an efficient hull is weight reduction. Weight also detracts from performance. ESI says tests show hull resistance could be reduced by 50 percent or more at design speed, which means the engine could be as much as 50 percent smaller. That, in turn, begets more space and weight savings through smaller tanks that carry less fuel.

The concept requires a special underwater hull shape with a large cavity to trap the air, which is blown in by a fan mounted in the bow. The cavity is closed off at the stern with a special flap. On the prototype, the hydraulically driven fan is powered by a Volvo Penta D3 diesel, but future versions might use electric power from a genset or from a hybrid main propulsion system. The hull also needs pronounced "rails" on each side that prevent the air from escaping and lend stability under way.

ESI says the M65 prototype achieved a verified fuel consumption of about 1.3 gallons per nautical mile at a cruise speed of 28 knots once the boat was optimized and in proper balance.