Ugo Conti’s patent, approved in April 2005, offers some clues, describing the craft this way: The boat is “an entirely different type of vessel that creates the minimum possible disruption of the waves. In other words, this vessel does not push, slap or pierce the waves but instead ‘dances’ with them.

“The vessel has a pair of flexible hulls flexibly coupled to a ‘cabin’ between and above the hulls, thereby allowing the hulls to independently follow the surface of the water. Motor pods are hinged to the back of the hulls to maintain the propulsion system in the water.”

The patent lists possible uses as rescue or patrol vessels, pleasure craft, military uses or research vessels for deployment of submarines or other instruments.

The patent notes the boat could move at 60 knots or more, with a range of 2,000 miles.

After leaving Ilwaco on Sept. 30, the boat was not seen again until early October, when it moored at the Marina Bay Yacht Harbor in Richmond, Calif.