A hull configuration for the planar surface region in the tunnel area between hulls(pontoons) in a fishing type catamaran. In the tunnel bottom surface is a raised frontwardly located center section adjacent the bow forms a venturi where low pressure is formed by incoming waves passing about the squared off rear portion of the center section. Behind the center section is a raised longitudinal stabilizer running to the rear(stern) of the boat which diverts and splits incoming air coming from the bow section to each side of the tunnel. Adjacent to the center section are two raised side stabilizers which straighten out incoming air and reduce the turbulence effects therefrom. On the rear ends of the two side stabilizers and the center section are through-holes that allow for venting excessive pressure from inside the tunnel to the interior of the bilge of the boat. Keel pads on the bottom of each pontoon hull each have exterior raised ridges (interior of lifting strokes) along the front portion flush to a rear portion surface. The keel pads give an extra planar surface for lifting the boat from the water.
A boat hull having an upper hull section, a pair of spaced apart substantially parallel elongated outer sponsons extending from a forward portion to a stern portion of a bottom of the upper hull section, the outer sponsons and upper hull section defining a tunnel therebetween; and an elongated center sponson extending along the bottom of the upper hull and positioned in the tunnel between and substantially parallel to the pair of outer sponsons and having a forward section with an upwardly extending trailing step wall defining an upward step in the center sponson, and an aft section that is located aft of the forward section, the aft section having an upwardly curved leading edge intersecting the step wall of the forward section. The upper hull section can have planar bottom.
