High speed outboard drive unit

摘要

An engine driven outboard drive unit for propelling a watercraft has a vertical drive shaft driving a horizontal propeller shaft on which a propeller is mounted. The drive unit has a gearcase torpedo which houses both the propeller shaft and an annular exhaust gas passage. The exhaust passage discharges aft through the plane of the propeller. A small annular projection is formed around the aft end of the torpedo to improve high speed performance.