Seadog LED Port and Starboard Navigation Lights

These lights are meant to be mounted PARALLEL TO THE CENTERLINE. If your boat has a pointy bow, you will need to make wedge-shaped shims to make these legal. Here's how to test them.

Clamp a straightedge upright to the exact center of the transom. Measure from its tip to each side of the transom. Adjust until these measurements are the same, so it's vertical with respect to the hull. (Not necessarily the ground.)

Now stand 20 feet dead ahead of the lights. When the stem and the straightedge are in line with one another, you're dead ahead of the boat.

You should see red and green. Leaning 12 inches to either side is a change of about 3 degrees. This is enough that the opposite light should fade to nothing. If it doesn't, you need to shim the front edges of the light outward further. Leaning only 6" gets you closer to the ideal, but 3 degrees is within the law. ("The intensities shall decrease to reach practical cut-off between 1 degree and 3 degrees outside the prescribed sectors."

When the lights pass this test, the aft angles must be correct because of the lights' design.

Here is an example of a port light installed on a wedge to get the correct angle ( photo courtesy Rob Rhode-Szudy)