Slippery Ships That Float on Air: Air-carpet hulls could sail faster, save fuel and cut emissions

[OKIsItJustMe]

http://www.sciam.com/article.cfm?id=air-cavity-system

Extreme Tech - December 30, 2008

Slippery Ships That Float on Air

Air-carpet hulls could sail faster, save fuel and cut emissions

By Steven Ashley

For three days in September, an ordinary-looking cargo ship traveled up and down Norway's Oslo Fjord. Few casual observers would have guessed that the 272-foot (83-meter) -long vessel was gliding on a carpet of air.

Air pumped about 25 feet (less than 10 meters) below the waterline into subsurface cavities—broad, shallow recesses built into the underside of the ship's hull—creates buoyant pockets that help reduce drag, allowing the craft to slip more easily through the sea surface, according to Jørn Winkler, founder of DK Group, the small Rotterdam marine-engineering firm that developed the new system. Because less energy is required to propel the ship, less oil needs to be burned and emissions can be cut by as much as 15 percent, he says.

Winkler reports that his company's demo ACS (Air Cavity System (pdf)) reduced the ship's drag by up to 7 percent, a performance that confirmed DK Group's earlier results in tank tests on a smaller model. Greater efficiencies should be realized by bigger, standard-size ships, he says, "because larger hulls pitch less and are generally more stable, which helps maintain the air lubrication effect."

The recent sea trial could turn out to be significant. After all, the world's merchant fleet—50,000 ships that transport 90 percent of global trade goods—emit 800 million tons of carbon dioxide annually (about 5 percent of the planet's total), according to the International Maritime Organization. Anything that can green up the operating efficiencies of new shipping by double-digit percentages would be a notable contribution.

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[DJ13]

1. Oh boy, I can just see a billionaire using that on their next Americas Cup entry