4. Position the Light
With a single bicolor light, position the fixture on the bow pointing dead ahead and the light pattern should be correct. With separate sidelights, curving bows and bulwarks can make positioning tricky. Many horizontally mounted fixtures have pointed backs that align parallel to the centerline. Vertically mounted sidelights are easier, as long as the vertical surface runs parallel to the centerline. Shim as required. Separate lights need not be at the bow, as long as they meet the visibility requirements stated above.
5. Mark and Drill Mounting Holes
Once the fixture’s in the correct position, mark the mounting holes, using the base of light itself as a template. Then drill each hole, being mindful of what’s behind the mounting surface, such as wires. Use a countersink to slightly bevel each hole to keep the gelcoat from cracking. At this stage, I prefer to pre-fit each mounting screw, driving it in gently and removing it. This ensures that the hole is the right size and also helps eliminate stripped screw heads during the actual installation.
6. Install the Fixture
Most LED nav lights come as “potted” solid-state units that are completely waterproof. To help seat the fixture, however, many have rubber or foam gaskets on the underside. Yet, I still like to bed the fixture, as well as the mounting screws, with marine sealant to keep water from seeping underneath and into the bowels of the boat. Lay a bead of sealant under the fixture before battening the mounting screws. A stainless-steel, chrome-brass or plastic beauty cap might screw or snap onto the unit to complete the installation.
Without proper shielding, LED switching circuitry can generate electromagnetic interference (EMI), resulting in static on VHF radios and stereos as well as “hash” on fish-finder displays. A CE mark on the LED indicates that it is shielded to attenuate EMI.