The Online Magazine For Amateur Boat Builders

LED Thoughts
by Gary Blankenship

Around 1979-80, I got a 10-watt solar panel for a 24-foot sailboat (a sloop rig held up by a maintenance-intensive matrix of fiberglass-covered wet rot). Ever since, the idea of energy independence, not only afloat but on land, has provided many hours of pleasant contemplation.

The evolution of LED lights has aided in those agreeable thoughts. In a way they parallel the development of solar cells. At first expensive and modest in ability, the quality is improving as the price comes down (the last 10-watt solar panel I bought cost, in real dollars, about one fifth to one sixth of that initial panel and small, handheld LED flashlights cost only a fraction of what they did a couple years ago).

Most people by now probably know the advantages of LEDs — low power consumption, little heat output compared to incandescent bulbs, and incredibly long bulb life. They will also continue to put out reduced but useable light with a nearly dead battery that will not light an incandescent bulb. According to Alpenglow, makers of high quality flourescent cabin lights, LEDs still are not quite as efficient as flourescent for large cabin lights, but they are using red LEDs for night light options on their lamps.

Practical Sailor in its recent review of cabin lights, noted that great strides are being made in LED lights almost monthly. (I admit to getting some sticker shock at the price of the LED lights evaluated; they ranged from about $72 to almost $200. The magazine rated the Alpenglow light set on high as “bright” and drawing .54 amps; the brightest LED fixture was rated at “medium” and drew .25 amps.) What surprised me was discovering when bopping around the Internet is that LED lights are now available in a wide variety of 12-volt applications, including in bulbs that fit commonly available 12-volt marine lighting fixtures. I was able to add six LED fixtures around our 30-foot boat, in addition to the three older type LEDs already installed. The total cost for the upgrade was around the $72 that Practical Sailor had for its cheapest LED light, but I’m sure their lights have more style . . . .

Before the details, some caveats. LED lights are frequently promoted as “super bright” or some similar verbiage. Let’s be honest. Although things are changing the only thing super bright about a super bright LED bulb is its name. A single bulb isn’t going to put out that much light. Put enough of them together, however, and you can get a useable light. Secondly, LEDs are directional in that each one puts out light in a fairly narrow cone. Not bad if you need a directional light (and most cabin lights seem to get mounted on bulkheads or ceilings), but if you want one that illuminates a circle, you have to find a bulb with LEDs mounted all around.

An interesting side effect is you don’t get blinded by an LED light unless you look directly at it (in fact it can be painful if you’re up close, and dangerous if it’s a UV light because you won’t feel pain from rays that can damage your eyes. Don’t mount UV LEDs on your boat. . . .). If you can mount LEDs in recessed or out of the way areas, you’re less likely to be “dazzled” at night than with an incandescent. Also, LEDs come in almost any color but the white ones actually put out a bluish-white light. Some people might find that a bit harsh; I prefer it to the “warm” incandescents. Finally, some LEDs are brighter than others. If you’re buying bulbs or lights, try to get both brightness figures (usually expressed in MCDs for millacandelas) and power consumption (usually expressed in milliamps).

The first LED lights added to my boat came from a South Florida supplier from whom I had purchased that last 10-watt solar panel three or four years ago. The company sent me a catalog with the solar cells, which included these three-LED modules. They were advertised as waterproof and came complete with switch and an articulated neck that allowed the lights to swivel. I bought three at $31 each and mounted them in the boat, intending them as reading lights. One swivels between the chart table and a single berth, and another between the galley and the second berth. The third is in the forward cabin/storage area. As reading lights, they work well for the berths. As area lights, they are inadequate. You can see in the cabin with them on, but the best word for the ambient level is gloomy. The one light is too directional to light up the whole chart table. In addition, the articulating necks have broken on two of the lights; those lights droop like . . . well, make up your own image.

With three LEDs each, these were the first LED fixtures installed on the boat. Good for reading, but not area lighting. In the background is the chart table.

I’ve forgotten the exact power consumption of these lights, but its something on the order of an amp hour per day — for all three combined. In other words, with only the 10-watt solar panel, even if all three lights were left on, the battery won’t run down, barring a couple months of heavy clouds. Pretty neat for reading lights.

Until I started browsing on the web, the only other LEDs I saw designed for marine use were generally designated as “courtesy” lights and have three LEDs. They are not focused like my reading lights, which meant they are generally too dim to read or see much by. The price also seemed high for a fairly dim light — $25 to $30.

But the Web revealed LEDs intended for truck and automotive use. Several companies are making red and amber LEDs designed to be side and marker lights for trailers and the like, and at least the red ones would seem to be effective as night lights. They also were waterproof. Further research showed there are now a wide variety of bulbs on the market to fit a variety of fixtures, from regular flashlight variety to 12-volt fixtures and even 110-volt regular light sockets. Some LED bulbs also come in their own housings, ready to mount and use.

I dealt with an Arizona company, found at For interior lighting, several of their 39 mm long “festoon” bulbs — the tubular type bulbs frequently found in automobile interior dome lights — were ordered, both white for regular use and red for night lights. They have nine LEDs each, aligned in two rows and lighting a decently wide arc. Also obtained were two small dome lights, 1 3/4-inch in diameter, with eight LEDs and a plastic cover designed to disperse the light over a wider angle. These lights are advertised as waterproof and even capable of being mounted underwater.

The nine-LED festoon lights used in the Seafit and auto interior light fixtures. There are 39 mm long; three other sizes are also available, as are three-LED versions. Photo courtesy of Superlumination.

The domelights are rated at 60,000 MCDs and consume 60 milliamps — or about 16 hours to use one amp hour. My impression is the festoon bulbs are quite a bit brighter, more than would be explained by one extra LED, and that’s backed by the technical data. They put out 75,000 MCDs but only use 50 milliamps, or 20 hours to consume an amp hour. They’re also more directional.

The eight-LED dome light. Two, with switches, were installed. They have sticky backs for mounting, but contact cement was also used. Less than two inches in diameter. Photo courtesy of Superlumination. A three-LED version is also available as are a variety of colors.

To mount the festoons, I got a Seafit economy dome light from Boat/U.S., normally $10 but discounted to $5 because of a small crack in the white plastic cover. It has a three-way switch and takes two white lights for normal work and one red light for night vision. At an auto parts store, I picked up some auxiliary interior lights with clear covers that hold the same size bulb and include a built-in switch. The price was less that $3 each. (Okay, so they may not hold up great in a marine environment, but this is for a test.) The dome LEDs need switches, which came from Radio Shack. Both the bulbs and dome lights were $6.99 each, not including a modest shipping charge.

How did it work out? Well first, compared to the incandescent festoon lights that came standard in the various fixtures, the nine-LED festoons were not quite as bright. I don’t have metering equipment to measure, but I’d guess the LEDs are about 50 to 75 percent as bright. The LED illumination, though, is noticeably more even. There’s no rating on the incandescent bulbs that came with the fixtures, but they look about the same as the 10-watt bulbs in my running lights. If that’s the case, each bulb would draw a bit less than an amp.
The festoons at 50 milliamps, would run for 20 hours on one amp hour, or about the same energy to run a regular bulb for one hour. Quite a savings in power. In fact, if all the LEDs are tuned on at once, including the reading lights, the total consumption is less than half an amp.

The Seafit light was mounted over the full-size chart table, about 30 inches above the surface. Since the LEDs produce an even light, I took the cover off. The results are great. With the two white lights on, it’s easy to read the chart or do any navigation-related activity on the table. Even with the single red light, it’s possible to make out most of the information on a chart and to see what’s needed on the table.

The Seafit economy dome light with two of the nine-LED festoons does a great job of lighting the chart table and navigation area. It also has one red light for night vision.

The auto interior lights were mounted one each about three feet over the head of each berth. They’re bright enough to read by, but I think I’d get eye strain after a while. The older, three-LED spotlights will work fine for that. More importantly, the new lights provide enough light to move easily around the main cabin without the half blind feeling. The gloom is gone. It ain’t super bright, but it’s more than adequate. I’m going to add a third one of these in the main cabin with a red light for night use.

The auto fixture with a festoon light. The line dangling from the bulkhead is used to hang a rustproof coal miner-type kerosene lantern for nonelectric light. The lantern was temporarily removed until after various and assorted hurricanes passed safely by. The galley is behind the bulkhead, but the Sea Swing cooker has also been removed for safety, and for home use of the power fails.

For the dome lights, one is mounted on the ceiling in the galley (across from the chart table) and the other in the forward cabin, which is where the porta-potti is along with storage shelves. Those lights are a bit dim to read by (not their intended purpose here) but plenty bright for the necessary activities in both those areas.

The auto fixture with a festoon light. The line dangling from the bulkhead is used to hang a rustproof coal miner-type kerosene lantern for nonelectric light. The lantern was temporarily removed until after various and assorted hurricanes passed safely by. The galley is behind the bulkhead, but the Sea Swing cooker has also been removed for safety, and for home use of the power fails.

I was tempted, but did not try an LED fixture with 13 LEDs (available in white and a variety of colors), it’s also waterproof. It costs less than $20, and is rated at 260,000 MCDs and a quarter amp of power consumption. That’s a bit more than four times as bright as the eight-LED dome lights (remember, all LEDs are not equal brightness) and more than three times as bright as the festoons, It has three wires for bright and dim options, so a three-way switch would be needed. Based on results from my initial installations, that would provide a good bright cabin light for my white-painted, 8-by-6.5 foot cabin — but for now I’m happy.

The dome light and switch mounted on the bulkhead in the forward cabin. The grey band below the light is common foam pipe insulation from Lowes, glued to the passageway to protect my cranium, or it might be to protect the bulkhead from my noggin.

The point is, there are now a variety of power saving LED lights out there, and very likely bulbs that fit current fixtures you have installed. (You may have to experiment. For example, if I want to use one of the nine-LED festoons as a reading light, it will have to be mounted no more than two feet from what I want illuminated.) And for the cost of one or two traditional and more energy intensive cabin lights, I’m able to put a little light everywhere on the boat, with extra brightness for reading and navigation areas.

The dome light lit. Below it and in the background is the interior auto fixture with a festoon bulb.

The LEDs are a great way to extend your battery power, and become more energy independent. While the bulbs are still more expensive than other types of lights, there are savings from not having to add a second battery or a noisy generator to keep up with power demands. If, like me, you can be happy with inexpensive fixtures and self-contained modules, the cost will be less than traditional off-the-shelf marine cabin lights. And the bulbs will likely never have to be replaced.

What’s next? Well, the running lights need to be replaced, and the ones offered in the Duckworks chandlery take festoon bulbs. But because of the narrow arc that the festoons illuminate, the housings would have to be modified to take two bulbs each. But that would make up for them not being as bright as the incandescent bulbs. Even with two bulbs each, the running lights would use only a fifth of an amp, as opposed to nearly two amps with the incandescents. Hmmm. . . .

For the technically inclined, below are a couple links that provide detailed information on LEDs, courtesy of Chris Bacon of Superlumination. The first link notes the difficulty of comparing incandescents, measure in lumens, and LEDs, measure in milliamps, but notes that LEDs are generally considered about five times as efficient as incandescents. My eyeball evaluations certainly agree with that.