Before you install a small outboard motor, make sure that your boat is in good condition. Prepare the boat's transom by replacing any rotten wood; reinforce it with plywood to strengthen it if necessary. Using a framing square, measure and mark the transom from the centerline of the keel. The correct measurements are 19 inches for a 20-inch shaft motor, and 24 inches for a 25-inch shaft motor.
Center the bracket on the markings you have made above the keel. If necessary, drill the bracket before attaching it to the transom. Use a marine sealant to cover any drill holes to keep the installation waterproof. Strengthen the inside of the transom with an aluminum plate. Complete the motor mount installation by setting the engine at the correct height for your boat.
Ensure that the cavitation plate is between 10 to 25 millimeters above the straight edge line of the keel. Next, secure a backing plate between the engine and the hull to reduce some of the vibration from the engine. To prevent water from seeping into the boat, seal all of the threads on the mounting bolts.
Consider upgrading your steering with a new engine. Boats with new engines respond better and are safer with hydraulic steering. Make sure that engine controls, switches and gauges are easy to reach. Clean up the boat's deck after any installation to prevent hazards that could cause dangerous problems on the water. If you want to use your old controls with your new engine, consider installing an adapter kit from the engine manufacturer.