An improved trimaran of a type having a central hull, a starboard outrigger, a port outrigger, a starboard crossbar for attaching the starboard outrigger laterally to the starboard of the central hull, and a port crossbar for attaching the port outrigger laterally to the port of the central hull is provided. The improvement comprises a starboard propulsor attached to the starboard outrigger for propelling the trimaran, a port propulsor attached to the port outrigger for propelling the trimaran; and a motor controller connected to both the starboard and port propulsors for controlling the combined propulsion of the starboard and port propulsors for controlling both the speed and direction of the trimaran by tank steering.