Mounting a Mercury outboard motor to your boat requires a good eye. Determine the center point, select the correct propeller height, lock the clamps, hook up the gas and you are all set. Where some people find mounting an outboard motor difficult is that outboard motors can be physically heavy. Basic launch motors run in the 50-75 pound range. As the horsepower rating increases, so does the weight of the engine. Before you mount your motor, make sure you can lift it, or make sure you have help.
Determine the center point of your boat's transom. The transom is the point at the stern (rear of the boat) where the outboard motor is mounted. Find the center point and mark it with your pencil or marker. It is very important to have a centered motor, otherwise you could find your boat drifting too far in one direction.
Open the clamp on your outboard motor. Newer motors have a knob that can be turned by hand. If this is an older model, you may need a pliers or wrench to open the clamp.
Set the motor on the transom at the center point.
Lock the clamp that holds the motor to the boat. This is accomplished either by hand or with the pliers used to open the clamp in the previous step.
Determine if your propeller is set at the right height. Using the clamp behind the transom lock, raise or lower the outboard. It is essential that propeller sits just below the water line, but that the water inlet is submerged. The outboard must be able to suck water in to cool the engine. When you have the correct height, lock that clamp.
Tie the engine to the boat with a safety line. Use your rope or chain and tie one end to the seat or rope anchor. Tie the other end to the motor. If for some reason your motor hits something and becomes dislodged from the boat, this safety line will hopefully keep your motor from sinking.
Connect your gas line from the motor to a full tank of gas.