Technical Detail Page 2

(See also Technical Summary page.)

CURRENT APPROACHES

Before I return to how to match the intended application to specific LED types, I want to make a few comments about current differing 'real world' approaches.

If we consider some of the various LED anchor lights on the market for instance, (now that there are some others!) we see various levels of quality in LEDs, driver design, and suitability for application.

In general, the more expensive designs are aimed at the marine market with all due consideration to the environment, whereas the cheaper versions seem to be generic designs modified a bit to make do. The best units all strive to maximize efficiency while protecting the LED array 'driver' electronics and the LED's from spikes and surges. The better ones also have enhanced features such as overvoltage sensors, day sensors, etc. All of the better designs have carefully chosen the LED's to match the required emission pattern, chromaticity, intensity, environmental parameters such as thermal issues, and expected lifetime with the application.

For example, one competitor to the FirstStar (all will be nameless here) is an expensive, well made unit, with a reasonably efficient dc-dc converter LED array 'driver' and a shatter resistant housing, (this unit it not a retro fit 'bulb). The unit is not bi-polar, and does not come with a day sensor as standard, nor are the electronics potted, although the unit is sealed and the electronics are coated. The design is fairly immune to surges and spikes. The light output is very good, and the input voltage is quite wide. As might be expected for a well designed and built product, it is pretty expensive.

Another competitor makes a light that is almost as bright as the above mentioned manufacture, but this one costs only one sixth as much! Why? Well, this light uses LEDs that are not rated to last nearly as long as the best ones for this application, and they have nowhere near the width of beam angle, so even though they look bright they are not nearly as efficient. In addition, there are big dark areas between the LEDs'' beam patterns. Also, even though there is some surge protection in this light, it is not nearly as robust a design electrically as the previous model. The 'driver' that powers the LED array is also much, much less efficient, and generates a lot more heat, potentially shortening the life of the cheap LEDs still further. The unit becomes dim at normal operating voltages, the light has no day sensor, is not potted or coated or encased for physical environmental protection in any manner, and will not fit into most fixtures as it is too big in diameter. To top it off, the base on this LED retro fit 'bulb' will not even go into most sockets on marine navigation lights! In sum, even though it costs only a fraction of what the first example costs, it's just not worth it.

A competitor who also makes a retro fit unit seems to have copied an early version of the FirstStar (I am flattered), at least as far as the LED array is concerned. However, he discarded the more expensive driver the FirstStar MKI used, in favor of a simple design that is nowhere near as efficient throughout its operating input voltage range. The unit claims to be brighter than our light...well, perhaps it is, but the real question has to be, is it more visible to the eye? (Given that brightness is measured by a machine, whereas with our pulse method the light will look brighter than it measures). That I doubt, especially when compared to a MKIII FirstStar. But the unit also has a stated operating voltage of only up to 14V...so I guess you are supposed to shut it off if you start charging the batteries. (I have tested the FirstStar MKIII by exposing it to 115VAC, it just shrugged it off, I have also left it plugged in to 30VDC for a week, no problem!) Or ! maybe just let it get fried and buy another one. The LED's themselves look to be second rate Asian copies of the more durable brands, maybe not so bad, but not as reliable or efficient either, just way cheaper. This light has NO physical environmental protection whatsoever for the LEDs, and poor protection for the driver electronics...humidity will kill it quickly. No day sensor, of course, they do not say if it is bi-polar so most likely it is not. In sum, not a smart buy.

The next example is a stand alone anchor light, a unit that has a solar cell and batteries built into the fixture/housing. This is a first rate product, plenty bright, very efficient, well made and rugged, should last until the batteries die, which they will eventually. So why pay a premium for a design that will sooner or later let you down? With a design that uses the house bank, you have many options to supply power and replacing the batteries or charging sources is much more cost effective than when done on the small compact scale needed for this stand alone design.

There are now several offerings in the LED navigation lights other than anchor lights. Besides the already discussed issues related to driver design, ie trying to get the 'bottom line' down by using a cheap inefficient electrically fragile design and offering no or poor electrical and physical environmental protection, there is a separate issue with navigation lights, that is sector coverage and overlap. LED's emit their light in a more or less conical pattern, unlike the incandescent bulb used in marine navigation lights that has a vertical filament that can for all practical purposes be considered a 'point source' at least in the horizontal emission plane(s). The result is that to get correct sector coverage you must start with a LED that has adequate coverage and then modify the beam pattern with optical elements, either light shields alone that have a three dimensional design (NOT a simple 2D vertical 'blocking strip') or with reflective/refractive elements. The designs that achieve good coverage all use some combination of optical elements, even if, as in the case of at least one design, that includes shielding the lights by using part of the boats structure. The designs that do not in some way modify the LED's beam (and yes, there are some) will have poor sector coverage and may well have sector overlap, resulting in a confusing display.

There are a number of D.I.Y. articles, and proponents will say that you can design and build your own anchor/nav lights for a fraction of what is costs to buy one, and the one you can build will work almost as well as one you can buy. Not so. There are many things to consider to make a light that is even reliable and has the required coverage, vertical and horizontal, and unless you spend an inordinate amount of time tinkering around with many designs to work out the solutions to these problems, you almost certainly will end up with a light that is not reliable, efficient, bright, and shows the required pattern(s).

Cabin lights are an entire subject just by themselves. I would venture to say that our StarDrops model is both the brightest and most efficient, also the most cost effective when you consider the amount of illumination per watt, and they have more user features than any one else's, and leave it at that.

If you don't want to buy a FirstStar light because you think it costs too much, fine, but then at least buy a light from a reputable manufacture, don't get an eBay special from some fly by night Asian entrepreneur who got what he knows about sailing by watching the Discovery Channel!

Return to Technical Detail page 1.