Difference Between Inboard and Outboard Motors

If you are looking for a big daysailer or a little travelling sailboat, you may be picking in between sailboats that have an inboard engine and those having an outboard motor. Each comes with specific benefits. These are two typical types of boat motors, and their names are obtained in the way that they are attached to the boat.

Outboard Motors

An outboard motor is a single system including engine, shaft and propeller (and in some cases fuel tank) mounted on a pivot on the stern of a boat. To steer the vessel, the whole motor is rotated with either a tiller fixed directly to the motor. For larger units, a hydraulic or rod coupling from a wheel. The engine axis is vertical, with a vertical shaft and a 90-degree gearbox underwater driving the propeller.

Many outboard brackets can be moved up and down to raise and reduce the motor. This is a beneficial function because the mounting does not necessarily provide sufficient space for all outboards to be slanted forward on their mounts. Measure this carefully if you're purchasing a sailboat with an installed bracket with no inclusive motor.

Inboard Motors

A conventional inboard engine is installed horizontally (or almost so) inside the boat. It sits below the waterline, with a shaft and propeller extending through a watertight stern gland into the water. The boat is steered with a conventional rudder, usually mounted behind the propeller to permit steering.

A boat can typically accommodate larger and more efficient inboard motors than outboard motors. This is mainly because of the position of the motor in the boat. These types of motors are popular with slalom skiers as they produce a smaller sized wake in addition to fishing boats in the sea because they have a low centre of gravity. If a much heavier vessel wants to have an inboard motor, they will need a motor too large in size and weight to be mounted at the aft end of the hull.

Sterndrive Motors

A sterndrive, or stern drive, is a kind of boat propulsion likewise referred to as inboard/outboard or I/O. The upper unit engine is located inboard, just forward of the boat stern, producing power by way of a shaft that goes through the stern to the lower drive unit (likewise called the outdrive) located outside the hull, which resembles the bottom half of an outboard. The lower drive system carries the boat propeller and consists of tailoring for the engine system. This unit manages the steering of the boat, just like an outboard motor.

Benefits of the sterndrive versus the outboard consist of greater offered engine horsepower, a tidy stern with no cutouts for outboard motor setup and no extending powerhead, making for easier egress and ingress for pleasure boat guests and convenient fishing. Advantages of the sterndrive system versus outboards include easier engineering for boat contractors and space cost savings with engines mounted all the way aft, allowing more tenancy space for the boat's passengers.

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