This one is interesting. The Rigging Co. did a nice job and replaced our rigging last year which including new wiring inside the mast and other bits and bobs getting replaced. We touched on this re-rig in a different post. We have slept well knowing that the standing rigging is essentially 100% new.
A teensy tiny part of that project was the installation of a new Forespar ML-2 steaming/deck light combination on the mast replacing whatever was there previously. Fast forward to today: In 12 months, we burned up two (2) LED steaming bulbs, even though we rarely had to use it that light.
The deck light worked flawlessly but the steaming light portion of the ML-2 was giving us problems. Something wasn’t adding up. So I knew we had to dig into this issue. The light is a single unit with 3 wires. The deck light points downwards and the steaming light is on the top with a reflective lens cover.
When the steaming light is powered on, the light facing forwards shine as you would expect and the light pointing backward is reflected forward with some reflective tape affixed to the inside of the cover. We climbed the mast to replace the bulb or investigate the cause several times.
Before I climbed the mast this last time most recently, some questions came to mind. Could the light that we have be defective? Should I just go buy a new light and install it? Was it installed incorrectly? Did I wire it incorrectly in the cabin? It is a relatively simple device, so I didn’t think the root cause could be complex.
I checked our wiring below the mast and it all looked to be in good condition. Then I went up the mast, and the first observation that I made was that the cover looked burnt up and had a coating of gray/white powder which would not easily wipe off by hand (no picture, unfortunately). I cleaned up the cover with some denatured alcohol.
The wiring on the back of the fixture looked fine. The wiring coming up from the mast and out to the fixture looked to be in good shape as well. I noted that we didn’t have any grommet on the exit hole to mininize chafe, but I didn’t see any unusual wear. I tested the steaming light fixture with a multimeter, and I didn’t see any issues; we were getting 24V. So I was puzzled.
A new light would cost me almost $170 US. That was a relatively big expense to make without understanding the root cause.
Then I remembered that the wiring on the back of the fixture was simply 3 wires. One for steaming, one for deck and the other is ground. If there was a problem with the steaming light, then I would not have been able to get 24V at the fixture where the bulb connects.
I contacted a few folks including Jimmie from The Rigging Co. who installed the light and also Ray. Both had a lot of good suggestions. Since I didn’t have another spare LED bulb, I decided to install an incandescent bulb in the fixture. I turned on the steaming light switch in so that I could get some instant feedback when installing the bulb up while I was up on the mast. As I climbed the mast and started to insert the bulb into the socket it lit up instantly. That was a good sign!
It was a bit windy when I did this, and I noticed the light bulb flickering on and off quickly. What I saw was the upper end of the bulb (cone shaped festoon style) was freely moving and wiggling in the upper arm of the light fixture. There upper arm of the light fixture was not securing the bulb making positive contact at all times. Seeing this, I bent the arm down to ensure contact at all times.
Back to the root cause. In my opinion, while using the steaming light for the few times that I did, the LED bulb was getting cycled on/off at a high frequency whenever the boat was rocking and heeling or when the mast was vibrating. Cycling LED bulbs on/off quickly will dramatically reduce their lifespan and cause them to burn out prematurely. Bending that upper fixture arm to put tension on the bulb is the solution to the problem.
If the Forespar ML-2 steaming light had a socket style design to positively holds the bulb this wound never have happened. But I think we have this one solved for now. Hopefully you can learn from this as well if you have an ML-2 or any similar design “festoon” bulb holder.
A big thanks to Jimmie at TRC, Ray and many others for brainstorming with me!
The Loxodograph 