Patent ID: 7666040

Claim:
A planing watercraft, comprising a hull having a starboard hull section and a port hull section meeting at a centerline, a tunnel formed at the centerline, and a traction swivel drive with at least one attached propeller mounted in the tunnel, wherein the tunnel has a forward sloping ramp section, a rear section that opens out at least partly into a cross section of the watercraft transom and a mid section contiguous to and positioned between the forward sloping ramp section and the rear section, wherein the rear section of the tunnel comprises vertical lateral wall surfaces from the midsection to the transom and wherein the vertical lateral wall surfaces diverge from a centerline of the tunnel through a distance of between 0.5 to 1.5 propeller diameters in size along the centerline adjacent to the transom opening, wherein the swivel drive has a vertical swivel axis located within the mid section, and wherein the at least one propeller is located not more than 2 propeller diameters aft of a junction between the forward ramp and the mid section.