Trickle-Down Power Theory
Advances in afforable technology are opening efficient diesel/electric power options to the pleasure boat market.

The world’s largest cruise ships, Royal Caribbean’s Freedom of the Seas and the even larger 6,400 passenger 1,180-foot long, 220,000-ton Genesis that will be launched in 2009, are diesel/electric powered. The single propeller of the world’s largest cargo vessel, the 1,302-foot long container ship Emma Maersk, is directly powered by a 109,000-hp Wartsilla diesel turning at just 92 to 102 rpm. However, when that’s not enough, her 88-foot long, 14-cylinder diesel engine can be assisted by two electric motors powered by five 4,140kW Cat diesel generators and an 8,500kW turbo-electric generator. Seems the designers of these ships know something about the attractiveness of diesel/electric power.

There’s no question that diesel/electric power is ideal for a cruise ship on which more than 75 percent of the power generated is used to operate the “hotel,” the massive air conditioning system, galleys, laundries, tens of thousands of lights, and all the rest of what amounts to a good size town. It’s also obvious that the 40,000 diesel/electric horsepower that can be delivered to Emma Maersk’s prop shaft will help get even that massive vessel moving. Diesel/electric propulsion also makes sense for builders of boats smaller than these leviathans. Nordhavn’s new 76-foot trawler is propelled by a Siemens ELFA diesel/electric system. The system has also been very successfully retrofitted to a 42-foot trawler. With recent advances, we believe diesel/electric propulsion will become popular in displacement hull boats as small as 30 feet. ...

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