It rises up out of the water on hydrofoil type thingys which means its displacement is negligible which allows it to go superfast (for a wind driven water craft). They say it can also handle rough seas while at speed as well. It looks like it would be a real blast to sail (but I imagine if you were to tack or gybe at speed you'd go ass over teakettle in a hurry).
http://www.youtube.com/watch?v=xFJocBvj-_wl'Hydroptère refitted in bid for record
l'Hydroptère is a 60-foot hydrofoiling trimaran. The outer hulls --- or amas --- are fitted with hydrofoils. Upon reaching a speed of about 12 knots, the boat lifts all its hulls out of the water and planes above the waves.
The so-called "flying yacht" set a category record last year, averaging 41.69 knots over a full nautical mile.
The all-carbon trimaran was dry-docked over the winter, where skipper Alain Thébault and crew reconfigured the boat specifically to make an attempt on the 50-knot title. Design changes have included shortening the mast, and optimising the boat's hydrodynamics.
l'Hydroptère was re-launched near Marseille last week. Thébault plans to spend the next few weeks conducting speed trials on a stretch of relatively flat water nearby at Port Saint Louis du Rhône, where the mistral winds frequently blow at 30-35 knots.
http://thetyee.ca/News/2008/05/30/SailingSpeeds/They've also got some more embedded video on their web site:
http://www.hydroptere.com/_en/