(Fortune Magazine) -- Propeller technology for boats hasn't changed much in the past 150 years. Now Swedish inventor Torbjörn Eriksson says he has designed a better propeller that, combined with a new hull design, is capable of speeds of more than 100 knots.

But it isn't just speed that Eriksson, a 49-year-old third-generation sailor, is after. His boat, Stormfågeln ("stormbird" in Swedish), will be able to go nearly twice as far or twice as fast as comparably sized boats on the same amount of fuel. "It's crazy that ships take so much energy when diesel fuel is expensive and environmentally unfriendly," Eriksson says.

A 44-foot prototype of Eriksson's boat, under construction near Stockholm, will be ready for trials on the Baltic Sea this fall. Stormfågeln, the company developing Eriksson's design, hopes to license the technology for near-coast use as ferries, luxury yachts, and coast-guard vessels.

The secret? The hubs of Stormfågeln's two propellers are above the surface, with only three of their ten blades in the water at any time. And the rocketlike hull touches the water in only three places, resulting in minimal resistance and greater efficiency.