US Patent 7878874 Marine vessel propulsion drive module

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.