A combined hull and steering mechanism for a marine vessel has a substantially rectangularly-shaped upper hull joined to a lower hull that is dual-tapered from its sidewalls to both its forward and aft portions. A directional thrust steering mechanism having a pair of vertical rudder blades positioned on either side of a conventional propeller extending from the centerline of the lower hull directs the water from the propeller, thus enabling the vessel to move more efficiently and with greater maneuverability in both forward and reverse directions. The dual-tapered hull permits a significantly better flow of water to and from the propeller and steering mechanism of the vessel, particularly when operating in reverse, thereby allowing the vessel to turn 360.degree. in its own length.