Abstract: The instant invention is a shroud/keel/rudder combination for use on a engine driven marine vessel having a vented tunnel propulsion system. The combination produces acceptable acceleration, minimal loss of speed, resistance to weed entanglement and optimized steering, in both forward and reverse, especially when used with surface piercing propellers.

Abstract: A drop-in-module consisting of a mass produced engine coupled to a drive system by use of a common mid-section mounting platform. The module provides a single assembly that can be easily installed and removed from a vessel. The drive system is based on motors using a vertical crankshaft orientation joined to a 90 degree gearbox with a forward-neutral-reverse transmission. A speed sensitive clutch arrangement separates the engine from the gearbox. The heat created by the air cooled versions of these engines can be vented into the propeller wash through a passage formed in the mounting plate.

Abstract: An improved tunnel configuration for tunnel mounted surface piercing propellers. The improved tunnel configuration provides a flooding suction to the tunnel to allow flooded propeller operation at speeds below planning. The tunnel is stepped whereby an upper portion of the tunnel is sized to allow the propeller to draw air at high speeds. The lower portion of the tunnel is sized to allow the propeller to be flooded resulting in smooth acceleration, improved handling in forward and reverse and a reduction of the transition period.