Gaining a comprehensive knowledge of boat motors is important, as it allows you to decipher what is wrong in case of malfunction. Recognizing a problem early on will allow you to avoid both physical and financial risk.



All three parts of a boat motor must be kept in good shape. If either the engine, propeller, or drive system fail to work properly, the motor will not run.

The drive system on motor boats may be inboard, outboard, or inboard/outboard (also known as a stern drive). The drive system controls the transfer of the engine's power to the water and directs the thrust. An outboard system places all parts of the motor together in a housing located on the outside of the boat.

The entire unit swivels to change direction. The outboard motor is lightweight, often portable, and takes up little to none of the boat's interior space. However, the weight of the motor can cause the boat to ride low at the stern and the cutout space where the motor is carried can make the boat prone to taking water in that location.

An inboard drive system moves the engine inside the boat, close to the center of the hull. The inboard location of the engine creates better balance in the boat. However, the inboard engine is generally heavier than the outboard system and critical interior space is reduced.

In a stern drive, or inboard/outboard motor, the engine is located inside the boat as with an inboard system. However, the rest of the motor is located outboard. This minimizes the loss of interior space while maintaining the balance and low center of gravity of the inboard system. The major disadvantage to this system is that the motor is more complicated, and therefore more prone to failure, than either the inboard or outboard motor.

The engine is perhaps the most important decision that must be made about motor boats. The most popular engine is the four-cycle internal combustion gasoline engine. This type of engine is sufficient for any boat up through a mid size family cruiser.

The engine is roughly equivalent to that of a heavy-duty truck engine. Remember that a gasoline engine must always be well ventilated to prevent fire or explosion. Two cycle engines are still available and are quite lightweight, but require adding oil to the mix. They tend to smoke and leak and are no longer considered ideal.

Diesel engines are in many ways superior to gasoline engines and are the engine of choice for large ships and commercial vessels, as well as some versions of the sports boat. They burn more cleanly and won't explode. However, the initial cost is much higher than that of a gasoline engine.

The final component in most boat motors is the propeller. At one time, choosing the proper propeller was a mysterious art best left to professionals. Now it is possible to choose your own. Propeller selection is still complicated, and it is best to consult with a professional or discuss your choices with experienced boat owners in a boat forum.

Take the time to make yourself familiar with boat motors. Doing so will allow you to successfully combine the components you need for a smooth running boat. If there is something you do not know about boat motors, consult an expert.