Among all the energy demands aboard a modern boat—electronics, pressure-water systems, watermakers, autopilots, refrigeration, and so on—it’s simple DC cabin lighting that’s often the largest factor in overwhelming the storage batteries. Turn on three measly 20-watt incandescent lamps and leave them on from dusk until bed time—say, four hours —and you’ll take 20 amp hours out of your system (3 x 20 watts = 60 watts; 60 watts / 12 volts = 5 amps; 5 amps x 4 hours = 20 amp hours.) That’s comparable to running an anchor windlass, under a working load of 40 amps, continuously for half an hour. The same is true at home, of course, where parents since the days of Edison have adjured their kids to turn the lights off when they leave a room. The difference is that on shore we notice the carelessness when the bill comes. On boats, we notice when the house battery dies. If the battery switch has been left on “Both,” or there’s only one battery for all duties, including engine-starting, that carelessness can spoil your day.
The power demands of lights are so important aboard boats that for this article we initially intended to cut to the chase and review only LED-based cabin lights. We had in mind a scenario in which a boat owner wanted to use LEDs to replace reading lights in the forward and main cabins, and dome lights in the main cabin and galley. We think of dome lights as spreading a wide angle of illumination, and bulkhead reading lights as more directional, although these, too, are often used for general illumination, and aren’t as strictly directional as a chart light in the nav station.
Would such a wholesale move be possible for both area and spot lighting? Yes. Would it be advisable? Not yet. In any case, LED lights really need to be compared directly with the other types of lights on the market, especially since most of the makers and purveyors of LEDs tell us that the technology is changing rapidly and markedly, and that what might be a decent cabin light now will be much better, and cost less, in a matter of months. So we decided to expand our scope and survey a wide sampling of cabin lights on the market, including LEDs.
Some basic concepts and definitions are in order, so that we can make reasonable comparisons.
A lumen is the measurement unit for luminous flux, the quantity of lamplight cast in all directions.
A lux is the measurement unit for illuminance, the quantity or density of light cast on a surface. One lux equals one lumen per square meter. (Illuminance can also be expressed in foot-candles, which measure light on a square foot of surface, but the foot-candle measurement is becoming obsolete.)
These definitions are intertwined with those of candelas, luminance, luminous intensity, and several more that help people get a grip on artificial light. For the purposes of this article, we’ll be speaking in terms of lumens, and measuring in lux units.
Of particular concern is the relationship of lumens and watts. For example, a 60-watt incandescent household light bulb rated at 840 lumens produces 14 lumens per watt. On a boat, a 10-watt xenon bulb might typically perform about the same, while a fluorescent bulb would produce a much higher ratio of lumens per watt.
The apparent “warmth” of a lamp’s color can be expressed through its color temperature in degrees Kelvin (K). The lower the color temperature, the warmer-looking the glow of the light. A candle flame has a color temperature of about 1800K. Sunlight at dawn or dusk is around 2000K. A 100-watt standard incandescent (tungsten) lamp is about 2800K. A standard “warm white” fluorescent would be about 3000-3300K. Direct sunlight at noontime is around 5000-6000K, and “daylight” fluorescents are in that range or somewhat cooler. And so on—up to the high numbers represented by various levels of sun/cloud combinations and cool blue northern skies.
Color temperature can be metered and measured, but we found it easy enough to eyeball the lights for any remarkable warmth or coolness. Those remarks are in the chart on pages 30-31.
Light Types—Pros and Cons
We’ll make the assumption that all of us are seeking pretty much the same ideals in cabin lights aboard sailboats: 1. They should provide a large number of lumens per watt. 2. The light they cast should be warm and welcoming. 3. They should produce little heat. (There are, of course, people who sail in colder weather who often prefer a bit of extra heat when they can get it.) 4. They shouldn’t cost much. 5. They should last a long time.
Obviously, no single light type can offer all of these things. So there are trade-offs to consider.
LEDs are narrow-beamed and directional. They don’t spread light, so if you want to use them as area lights, you have to arrange them in a cluster so that individual LEDs shine outward in a pattern. LEDs deliver long life (forever, for most practical purposes), hardiness (no fragile glass or filaments to break), very low power consumption per diode, and low heat per diode. On the downside, they’re still quite expensive, and while red LEDs are good as night-vision lights in the nav station and cockpit, white LEDs emit a cool, bluish light, which few would say makes for pleasant company. Individual LEDs vary in quality, and are culled and graded by manufacturers before they leave the factory.
If this sounds like faint praise, it isn’t. The long lifespans of LEDs eventually justify their cost. They’re extremely versatile and hardy, and with the technology developing almost hour-by-hour, they’re becoming both warmer and less expensive (see this month’s PS Advisor).
Fluorescent bulbs come in several varieties, such as standard, compact, and cold cathode. Color temperatures vary from about 2700K all the way to 5000K and above, depending on whether the tubes are standard, “warm-white,” “daylight,” and so on. The advantages of fluorescent bulbs are long life, excellent lumens-to-watt ratio, low heat, and reasonable cost. The downside of the typical fluorescent lamp is a color temperature that’s too blue and cool; however, some fluorescents are quite warm, as we shall see. Also, all fluorescents run on AC power, which means that they must be adapted to DC power systems by means of a built-in inverter. Sometimes this can cause radio frequency interference, so be careful if you mount a fluorescent light near sensitive electronics and communications equipment.
]Incandescent lights of the familiar tungsten-filament variety cost less than any other type, and offer a warm glow. Bulbs are readily available. The downsides are that they burn out relatively quickly, offer the lowest lumens-per-watt ratio, and produce heat. Interestingly, it’s getting harder to find standard incandescent bulb lamps in marine stores these days. (Replacement bulbs are available, but new lamps are scarcer.) Most light makers are now going with halogen and xenon bulbs.
Halogen and xenon bulbs are closely related to the standard incandescent. The difference is that the inert gas inside the bulb contains halogen, which helps return tungsten particles to the filament, slowing the burn-out process as well as enabling the filament to be heated to a brighter temperature without. In order for the process to work, the bulb has to be very hot. This, in turn, means that the bulb needs to be made of thick, heat-resistant glass or a quartz-based crystal.
Some bulbs contain high-quality xenon as the inert gas. This enables a more efficient process of returning tungsten to the filament, increasing brightness and bulb life still further.
Aside from cost, the downside to all this is—you guessed it—more heat, which can not only make it uncomfortable for people inside the boat in warm weather, but cause fire if a light is thoughtlessly installed. Nils Nelson of D.R. Smith & Associates told us some hair-raising stories of people who insisted on installing high-wattage halogens in non-fire-resistant headliners and other areas where their heat couldn’t be dissipated properly. “Just because a fixture will accept a higher-wattage bulb doesn’t mean you should install one,” he cautioned.
Even so, halogen bulbs are an excellent balance of cost with effective light. They typically show a whiter, higher color temperature than standard incandescents; about 3200K versus 2800K. This can be harsh in some situations, but makes great task lighting. And they have a good lumens-per-watt ratio of about 15.
As standard-issue sailors, not experts in lights and lighting, we admit being a bit flummoxed by the prodigious amount of science involved in the study of light—its color, intensity, warmth, concentration, etc.—as well as by the large number of artificial lighting products available for boats, and the variations and overlapping characteristics of many of them. Add to that the fact that several of the light makers and light experts we talked to are in disagreement over the finer points of both science and light engineering, and it was difficult to figure out how to bite off a digestible amount for this article. When we were griping to our friend the shellfisherman about the vastness of this topic, he said: “Hey, people don’t need to know all that. What they need to know is, when you’re down in the cabin, trying to make some time with your honey, do you light the oil lamp and turn it down low—or flip on the halogen?”
The man, of course, is entirely correct. It’s not so difficult to define what kind of light serves what purpose best. Consider what Al Johnstone of J/Boats had to say when we asked what kind of lights his company preferred in different locations aboard: “In general, we use halogen lighting in main cabin areas for reading lights and red/white domes, and fluorescent fixtures in head areas. Ninety-eight percent of the lights are sourced from Imtra (Cantalupi) and Hella Marine (including domes and nav lights). On a boat like the J/105 we’ll use very simple plastic-finished self-contained halogen lights, whereas on the J/42, J/46 and J/160, we’ll go for a complete dimmer system for ambient lighting in the main salon and galley areas, in addition to chrome-finished self-contained reading lights. We occasionally will still use incandescent lighting, depending on the application and available fixtures/style. We continue to watch with interest the developments in LED lighting, due to the low energy requirements. We have little experience yet with xenon fixtures.”
These views would be typical, we think, of many sailors—we lean toward warmer lights for area lighting, and fluorescent for galley, head, and engine-room areas. When we can substitute LEDs without sacrificing too much warmth or dramatically increasing cost, we will.
And so it remained for us to gather the sampling and try to find lights that we’d actually like to buy. The only way to get to the bottom of that essential question was to line ’em up and shine ’em. The results of our explorations are shown in the big chart on the preceding pages.
What and How We Tested
We went shopping at West Marine and ordered a pretty fair sampling of what’s on their shelves. We also solicited lights from several of the big light purveyors and talked to experts about the state of the art in DC cabin lighting.
Generally, the lights we evaluated were in two categories—overhead dome-type lights with wide light spread for area illumination, and bulkhead-mounted reading lights. Also included are a few LED lights that could go either way, and LED replacement clusters for incandescent bulbs.
We powered the lights with a 12-volt power supply, dimmed the office to an ambient light of two lux, and turned on the lights one by one. We measured the spread of each light from 12″ away, and took photos for comparison. We took a multitude of light meter readings for each light from different angles and distances, using a Meterman LM631. Then, because handheld light meter readings can fluctuate so much, we took into account the spread of readings, did some averaging, added some Kentucky windage, and came up with the rather simple ratings shown on the chart—Dim, Low, Medium, Bright, and Intense.
To measure heat produced by the lights, we used a Raytek Mini-Temp infrared temperature sensor to report the surface temperature of a piece of brown particle board held 6″ from the front of the lens for 10 minutes. (In each case, the ambient office temperature was kept at 75°.)
We measured current draw using a Radio Shack digital multimeter.
Over the course of about six weeks, we spent quality time with each light in an otherwise darkened space, reading and contemplating the mysteries of the universe.
The results of all the measurements, along with ratings and subjective comments, also appear in that mammoth chart.
Noted in Particular
The Alpenglow compact fluorescent light has received words of praise several times in this publication over the years, and we see no reason to stop now. The fixture is trimmed in attractive wood; the light is warm and adjustable in four levels (two for the red LED light, two for the white fluorescent), and the light it casts will pleasantly fill the typical saloon aboard a big variety of boats. And, we think it’s fairly priced (see chart).
The cold-cathode fluorescent lights from Taylorbrite (Taylor Made Products) deserve a very positive mention. We looked at the self-contained bulkhead-mounted reading light and were impressed by its design and the warm, even light it cast. It’s expensive, and you would have to replace the whole fixture—but it should have a very long lifespan. Consider these if you’re thinking of replacing reading lights in the master cabin.
Among the incandescent dome lights, we’d buy the mahogany-based West/ABI 20-watt xenon model 260786, and put it on a dimmer, or the Imtra/Cantalupi halogen “Chip.” For an incandescent bulkhead light, we’d go with the Catalupi “Patty” model.
As for LED lights, in our view they’re still a bit too cool-colored and directional to be used where a warm mood is a must, but if you can use a coolish, medium-widespread LED for reading in the bunk, Daniel R. Smith’s “Little Inagua” would be a good bet. Another strong contender for that job would be Imtra’s F1 “warm white” cluster, which at this writing is just going to market. The former is more of an whole-bunk light, the latter more for directing right at a book. Imtra’s Touch LED would do very well on its gooseneck over a nav table.
Lamp shades, lens types, and interior reflectors can make a big difference in the intensity, spread, and color warmth of any light. So can the depth of the bulb in the socket, and the color and reflectivity of the surrounding areas. Light will behave differently on a white Formica surface than it will on mahogany—and differently on the mahogany, depending on whether the wood is varnished in a glossy or matte finish. Dimmer is often better than brighter, and narrow better than wide.
Filament-based cabin lights can be adjusted for both light output and power demand with dimmers, which can be a simple rheostat type (an energy-waster and heat-producer) or a more sophisticated dimmer such as that made by Reddford Technology (www.reddford.com), reviewed in the January 1, 2000 issue of PS.
Also With This Article
“Value Guide: Cabin Lights”
• ABI, 800/422-1301, www.abimarine.com
• Alpenglow, 406/889-3586, www.alpenglowlights.com
• Aqua-Signal, 011 49 421 4893-224-205, www.aquasignal.de
• Daniel R. Smith & Assoc., 561/842-5704, www.drsa.com
• Deep Creek Design, 615/646-2532, www.deepcreekdesign.com
• Gator Lights, 941/355-4488, www.interconmktg.com
• Guest, 800/767-8541, www.marinco2.com
• Hella Marine, 770/631-7500, www.hellamarine.com
• Imtra (Cantalupi), 508/995-7000, www.imtra.com
• Lumileds, 877/298-9455, www.lumileds.com
• Perko, 305/621-7525, www.perko.com
• Reddford Technology, 208/666-1955, www.reddford.com
• Sailor’s Solutions, 631/754-1945, www.sailorssolutions.com
• Taylorbrite (Taylor Made), 941/708-0940, www.taylorbrite.com
• Thin-Lite, 805/987-5021, www.thinlite.com
• Weems & Plath, 410/263.6700, www.weemsandplath.com
• West Marine, 800/262-8464, www.westmarine.com