I'd like to thank licensed ship captain and editor of the gCaptain.com blog, John A. Conrad, for this one: a ship that floats on a curtain of bubbles.
The Bubbling Ship is a concept devised by Yoshiaki Kodama, director of the Advanced Maritime Transport Technology Department at Japan's National Maritime Research Institute in Tokyo. The ship would blow bubbles from slits near the bow of the ship. The bubbles would travel along the hull, reduce friction, and hence increase gas mileage.
Is it feasible now? No, but that's what research grants are for. Ships are one of the largest consumers of diesel fuel in the world.
In any event, Captain John has assembled a list of his top 10 green ship concepts. Among the ideas: putting a parachute-like sail on a ship, an idea being championed by KiteShip and SkySails. SkySails in fact recently completed a two-month voyage and found that the sail cut fuel consumption by 20 percent.
There's also a boat with a giant wind turbine, and the Solar Sailor from Australia.
Captain John's site also features an interesting collection of clips about nautical mishaps. Check it out, sailor.