Abstract: Four spars project downward and outward from a common juncture; a mast projects upward from the same juncture. Adjustable cables interconnect all the distal ends to each other. Thus a uniquely strong and light pentahedral-shaped space frame is provided. A unique system for cable length adjustment makes it practical to reconfigure the geometry of the vessel while underway. The vessel can be made tall and narrow for easier maneuvering, in light winds, or broad and low for maximum capsize resistance. Two hulls provide a suitable low speed displacement shape. When sufficient propulsion force is present, however, these two hulls can be split into four hulls, each of a planing shape and each connected to a spar. The wind drag, that is noramlly associated with frames of this nature, is transformed into useful forces by airfoil-shaped spars which are rotatable. These forces may be used to produce a downward push to prevent heeling over, a lift to reduce hydrodynamic drag, and a propulsive push.

Abstract: A colapsible light and strong vessel adapted for movement over water having a substantially terahedral frame comprising three elongated rigid members each connected to a buoyant hull and which meet at a common juncture, the hulls are configured such that one hull is forward and the other two aftward, a fourth rigid member projects upwardly from this juncture, A plurality of stays are connected proximal to the distal ends of these four members. A fifth member is connected to the two aft members proximal to the the aft hulls, this fifth member may serve as a stay, decking is connected to this aft member and to the common juncture. An engine is connected proximal to the forward hull. A light weight sail is provided which comprises a plurality of elongated airfoil shaped surfaces.