LED lights: are they worth the trouble?

[NetDoc]

I like the idea of LED lights. I like the idea so much, that I am equipping my nav lights with them. Ultra low current and they just won't "blow" are the key factors in this decision. But, as with most things, there might be a drawback that I am not seeing. Will they be in compliance with Coast Guard Reqs? How will they stand up to the corrosive forces of the ocean? Currently I have a bow green/red light and a single rear transom light and both are powered by festoon bulbs. Is that enough? Should I add a raised all around white light on the stern as well? I have a 23' Fibra power boat and live in Key Largo, Florida. I thought I knew the rules, but some doubts have entered my mind.

On a related issue, I want to add some red LEDs under the gunnel to light up the deck for night diving. How easy is it to control their intensity using a standard pot? I wonder what ohm pot I should use?

 

[dingbat]

Re: LED lights: are they worth the trouble?

I'm on the fence with LED on a boat. Power isn't an issue and rarely do I have bulbs burn out. Most failures are caused by corrosion and or vibration. None of the LED I looked at addressed the corrosion issue. Can't see paying 3-4 times the price to save a couple of watts of power

 

[ssobol]

Re: LED lights: are they worth the trouble?

I replaced the incandescent bulbs in my nav lights with short LED light strips. They are brighter and draw less power than the bulbs. They'll last a loooong time so they are wired in (no sockets) which will prevent issues with corrosion. When using white LEDs the color filter on the nav light controls the light color (not the LED) so there should be no issues with the CG. The LEDs are brighter than the bulbs they replaced so the viewing range should be better (the CG specifies the minimum range the light should be seen).

Originally I tried using green LEDs in the starboard nav light (kinda makes sense). However, the green light from the LEDs was a different green than the light filter and the nav light was pretty dim. White LEDs fixed this. Seems that the color pass of the green nav light filter was pretty narrow.

The brightness of the LED is controlled by the current flowing through them, not the voltage (above a certain minimum). To control the brightness you need to put a pot in series with the LEDs. You should also have a fixed resistor inline with the pot so that the resistance never gets less than a certain value. There are calculators online that let you figure out the value of the fixed resistor based on the number of LEDs, the circuit configuration, and the supply voltage.

Since the value of the fixed resistor is usually between 50 and 250 ohms, a 500 ohm to 2K pot will probably provide enough control, depends on what minimum brightness you want. You could also get a pot with a switch in it that would turn the lights off when they are turned all the way down. A larger value pot will have a smaller usable adjustment range.

I placed a number of short LED strips in strategic places around my boat as courtesy lights. They are white and not dimmable but have an on/off switch on the console. I simply stick a strip of LEDs where I want them and run a couple of thin wires. With no need for a lamp fixture or holder, these can go into some pretty tight places to get them out of the way.

Strips with 18 LEDs (~1 ft) can be had online from about $6/foot. This can be used whole or cut into up to 6 individual strips. You can order these in 1 foot increments or buy larger reels.

 

[NetDoc]

Re: LED lights: are they worth the trouble?

I know that water absorbs the LED light spectrum far quicker than an incandescent or HID bulb. They are fine as my back up lights underwater, but I use a 20W HID as a primary to light up a cave or a wreck for this very reason. They can be far brighter on the surface, but they dim an incredible amount below. That's why I am worried about Coast Guard approval. I wonder how visible they are in a rain storm?