Stern Drive (Inboard/Outboard)

A marine propulsion system combining an inboard engine with a steerable geared drive unit mounted through the transom.

The engine drives the external leg through a transom assembly; gears turn one or more propellers, and steering pivots the leg to direct thrust. The leg can normally be trimmed and raised for performance, shallow water or servicing.

Bellows, universal joints, bearings, cooling passages, anodes and gear oil require scheduled inspection. Damage or neglected bellows can lead to loss of drive or serious water ingress, so maintenance intervals and manufacturer procedures matter.