Planing boat having stepped hull bottom - of tunnel shape for trapping air cushion

摘要

Stable planing is possible with outboard motor boats having this hull design, in which air is forced under the hull via one or more openings in the planing step. The air may be supplied from ram intakes above a forward deck, and is trapped under the hull due to the tunnel shape of the hull bottom, the shape being accentuated by side keels or air cushion sidewalls extending aft from the step. During planing, the air cushion is set up both force and aft of the step, and the hull may contact the water at three areas, namely two side areas forward of the step and a third area at the stern end of a central keel.