Boat Engine Types Explained

Engine Types

Now let's look at the three types of engines you'll find on powered boats: outboard, inboard and stern drive engines.

What is an Outboard Engine?

This is an outboard engine. Outboard engines are mounted on the transom of the boat, outside of the boat's hull, which is why they're called "outboards".

Outboard engines are used to both power and steer the boat. To steer an outboard you need to move the entire engine. On smaller boats, this is often done using a hand tiller, while on larger outboards a steering wheel adjusts the direction of the engine.

What is an Inboard Engine?

Inboard engines are located inside the boat's hull. Inboard engines are four-stroke automotive engines that have been modified for use on the water. These engines power a drive shaft that is connected to a propeller.

Unlike an outboard, an inboard engine does not also steer the boat. Instead, inboards have a rudder or rudders that are located behind the propeller and controlled by a steering wheel.

What is a Stern Drive Engine?

The last type of engine is the stern drive, which is sometimes called an "inboard-outboard" because it shares features of both types of engines. Similar to inboards, stern drive engines use a four-stroke automotive engine mounted on the inside of the hull to power the boat.

Like an outboard, there is a drive unit used to steer the boat. To steer a stern drive, turn the steering wheel, which then turns the drive unit, and determines the direction of the boat.

What is a Jet Drive Engine?

A Jet Drive engine uses water to propel and steer the boat. Water enters in through an intake on the bottom of the boat and is accelerated through the jet drive unit at the transom, thrusting the boat forward.

Steering is achieved by changing the direction of the stream of water as it leaves the jet unit. REMINDER – Because steering is dependent on the water jet, Jet Drive engines will lose some steering control at low speeds.

Boat Hull Types | Boat Size Classifications