Abstract: A multihull windsurfer providing increased sailing stability, exceptional steerability and providing a moveable mast allowing for an adjustable sail carrying capacity. The preferred embodiment is a catamaran with hulls that are elongated, upwardly curved and substantially triangular in transverse cross-section, thereby forming keels. Dual rudders, disposed in tandem, are mounted under each hull and are controlled through a steering assembly. One rudder in each pair is removable so that the steering sensitivity of the boat may be varied. The mast is fully articulating and is disposed with a sail and a manually engageable boom. The mast is carried on a mast mount comprising a mast track assembly which is slidably adjustable fore and aft, so that the mast may be moved forward or rearward on the vessel, thereby providing for an adjustable sail area. The hulls are attached to and held substantially parallel by a platform providing deck space for the sailor.