The vehicle with the hull suitably shaped to develop the hydrodynamic forces during forward motion, sufficient to support the craft with a substantial proportion of the hull out of the water. The wetted area is thus smaller than at a low speed, and so for a given speed the viscous resistance is also reduced. A semi-planning vessel is a craft that is supported partially by the buoyancy of water it displaces and partially by the dynamic pressure generated by the bottom surface running over the water.