Choosing the right outboard boat motor requires careful consideration of many factors. The boat's size and its intended use are perhaps the most important two. Others considerations when choosing a 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 motor that is not as powerful as the type used by experienced boat operators. The design of the motor can also be a determining factor since some designs are not offered in all sizes.
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 occur when a large motor is operated at extremely slow speeds for long periods of time. Another option to consider includes the choice of 2-stroke or 4-stroke 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 one. 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 motor can be traded in on a larger model or used on a different, back-up boat.