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3 Main Types of Boat Engines

What Is the Difference Between Inboard, Outboard, and Inboard/Outboard (I/O) Engines

Did you know there are three types of motors? – Inboard, Outboard, and Inboard/Outboard (I/O). Each motor performs differently. Here’s a simple breakdown of each model to help you decide which one is right for you.

1. Inboard Engine

There are 2 types of Inboard engines, D-Drive and V-Drive.

Direct-Drive Inboard Motors

With Direct Drive motors, the engine is mounted in the center of the boat with the prop and rudder built into the hull (underneath the boat). Direct Drives are used specifically for ski boats as they leave a very little wake.

V-Drive Inboard Motors

V-Drive motors are stowed under the transom seating, with a Prop and Rudder built into the hull (underneath the boat). V-Drive Inboard engines are most commonly found on watersport boats making it easy to wakeboard, wakesurf, tube, kneeboard, and anything else you want to try behind the boat, including skiing.

To make larger wakes for wakeboarding, tubing, and wakesurfing, inboard boat manufacturers use built-in Ballast Sytems, Surf Systems, and unique hull designs to manipulate the wake. To scale back the wake to allow skiing, boaters often choose a “Crossover” model V-Drive inboard boat, like the MasterCraft XT Series, for example, designed with a hull that can produce very little wake when the added ballast and surf systems aren’t in use.

Examples of Boat Manufacturers That Use V-Drive Motors

Malibu Boats | Nautique | MasterCraft | Moomba | Tige | Supra | MB |

2. Outboard Engine

Outboard engines are the idyllic choice for fishermen and light commercial inshore boats. Outboard engines are mounted on the outside of the boat, high on the transom, and can be tilted completely out of the water making it very easy to perform maintenance and if need be, replace. With mostly positive attributes, outboards do lack power and torque. In order to get the power an inboard engine produces, there must be multiple outboard engines mounted on the transom.

3. Inboard/Outboard (I/O) Engine

Inboard/Outboard (I/O) engines otherwise known as Sterndrive combines inboard power with outboard driveability. The engine’s drive unit lies just below the swim deck with the motor mounted under the transom. Sterndrives are mostly used in “pocket cruisers” aka, boats less than 30 feet long that have amenities like a head, galley, and sleeping quarters.

The advantages of a sterndrive over an outboard engine are sterndrives have more horsepower and allow for a more attractive transom as the engine is hidden beneath the boat. They are also easier to fish on.

The advantages a sterndrive has over an inboard are sterndrives have no need for a prop shaft or rudder system making it easy to trailer and operate in shallow water. Sterndrives also allow for more space in the interior passenger cabin of the boat as the engine is mounted all the way in the back of the boat.

— Since 1965 —