sterndrives

A sterndrive, also known as an inboard/outboard (I/O) drive, is a marine propulsion system that combines elements of both inboard and outboard motors. The engine is located inside the hull of the boat, similar to an inboard motor, while the drive unit, which includes the propeller and gearcase, is mounted on the exterior of the transom. This drive unit can be tilted up and down, allowing the propeller to be lifted partially or fully out of the water.

Sterndrives offer several advantages. They provide a good balance of performance and efficiency, and the engine placement within the hull contributes to a quieter operation compared to traditional outboard motors. The ability to tilt the drive unit simplifies trailering, docking, and maintenance, as it reduces the draft and allows for easier access to the propeller. They are commonly found on a wide range of recreational boats, from runabouts to larger cruisers.

The sterndrive system consists of an engine, a transmission, and a lower unit containing the propeller. Power is transmitted from the engine through the transmission to a drive shaft that passes through the transom and connects to the lower unit. Steering is typically achieved by pivoting the entire drive unit. While offering versatility, sterndrives can be more complex to maintain than outboard motors due to the internal engine and the external drive components.