Remove the boat from the water.
Determine the light's mounting location.
Hold the light in place and drill one of the light's screw holes into the hull. Size the hole according to the screws included with the lights.
Install a mounting screw loosely into the screw hole to hold the light. Then use a level to position the light completely straight and drill the second screw hole into the hull. Leveling the light is necessary only for rectangular lights.
Install the second screw to attach the light to the hull.
Mark the outline of the light into the hull with a metal scribe.
Unscrew and remove the light from the hull.
Remove the paint from inside the scribed area where the light will install with fine-grit sandpaper.
Drill a hole completely through the hull for the light's power wire. Drill this hole slightly off-center from the middle of the light, if possible.
Apply a bead of marine caulking around the perimeter of the back of the light. Also cover the first three to four inches of the light's power wire with caulking.
Place the light back into its mounting position and tighten the mounting screws with a screwdriver.
Caulk around the power wire where it comes through the interior of the hull.
Clean excess caulk from the edges of the light and the hull interior with acetone.
Attach the power cable to a fused power supply inside the boat. Some lights come with stand-alone power supplies that mount inside the boat, while others have kits to integrate the new lighting into the boat's existing electronics.
