Choosing the right outboard boat motor requires careful consideration of many factors. Boat size and the intended use are perhaps the most important two. Others considerations when choosing an outboard boat motor include the type of water on which the boat will be used as well as the experience of the boat owner; inexperienced boat owners should choose an outboard boat motor that is not as powerful as the type used by experienced boat operators. The design of the outboard boat motor can also be a determining factor since some designs are not offered in all sizes of motor.

Placing an outboard boat motor on a boat that is too big for it can lead to many problems. One of the most noticeable is the inability of the boat to come up on plane. A small motor is not able to generate the speed to allow a large boat to rise up out of the water. This can also be a safety issue, as the motor may not be able to push a large boat against a strong current. This can lead to a boat being out of control and at the mercy of the wind and current.

On the other hand, if an outboard boat motor used on a vessel intended for slow speed trolling is too large, the motor may suffer from the continual slow speed operation. Fouled spark plugs and overheating often accompany a large motor when operated at extremely slow speeds for long periods of time. Another option to consider includes the choice of 2-stroke or 4-stroke outboard boat motor. Often a 4-stroke engine will operate at slower speeds much better than a 2-stroke. The latter will suffer from oil-fouled plugs when not given the opportunity to clear itself out with a high-speed run.

With the tremendous power production of the larger outboard boat motor, it is often wise for the inexperienced boat owner to choose a smaller, less powerful motor. Pushing a large motor to its upper level of performance can often overwhelm an inexperienced boater and lead to disaster. A boat moving at top speed is easily upset by the smallest movement of the controls. Starting out with a smaller motor is a productive method of gaining experience. Once mastered, the smaller outboard boat motor can be traded in on a larger model or used on a different back-up boat.