I was delivering a new-to-them sailboat with a customer last week. There was an obvious issue with the deck
lights. We could clearly see the sidelights from the cockpit
. Clearly something was wrong for lights whose visibility angle should only be 22.5 degrees behind the beam. The assumption was the mounting bracket was bent, or inappropriate, or something.
When we were doing our post delivery inspection
, it turns out the bracket was fine, and so were the fixtures. So what was the problem?
This was a pair of AquaSignal Series 40 lamps designed for a festoon style tungsten bulb with a single
, vertical, filament. The bulb had been replaced with an aftermarket LED bulb specifically sold
for use in "nav lights". The light emitting part of this bulb is at least 100 times larger in diameter than the fine filament of the bulb the fixture was designed for, making a total mess of the angles with large amounts of spill over both around the bow, and back toward the stern.
Why is this a problem? If you can see BOTH red and green lights from your boat
, you would know that the oncoming vessel is pointed very close to directly at you, and make your collision
avoidance decisions based on that. Except on this boat
, the red/green overlap on the bow was almost 45 degrees, just because of installing the wrong bulbs.They could make a significant turn to alter course, and STILL show you both red and green side lights.
In addition, when the fixtures were disassembled to put the right bulb in, the internal metal parts
crumbled away from corrosion
. Filament fixtures are at best, poorly sealed, and they will typically fail long before the LED. You spend the extra money
for the LED bulb and you don't really get full use of it before the fixture fails. Fixtures that were designed for LEDs are typically potted and fully sealed, and they will allow the LED to life a long and happy life, with proper light brightness, color, and visibility angles.
Remember, the Coast Guard approval for your fixture, is ONLY valid for the bulb that was used to do the tests. If you are buying
a bulb other than the exact one that came with the fixture, ask the seller if the combination has been USCG approved. If not... DON'T buy it!