MacGregorSailors.com

1.See for example posts on this board on May 17 '04 re LED anchor lights.
2.Same includes my post re my DIY unit running a Luxeon I Star 1.2 watt side emitter at about 1/2 power (about 175 mA thru the LED and so equivalent in lumens to maybe 8 +/-conventional super bright white LEDs, and with the additional advantage of radial, i. e. planar, rather than axial, primary light output) and further focused by a scrounged Megalight Fresnel lens. Multiple times brighter than a commercial garden LED light or the stock Davis with its small bulb (and I suspect with its big one).
3.An earlier DIY unit used no lens and a radially aimed array of 16 evenly cicumferentially spaced conventional ~2.5 cd 45 degree half angle LEDs with about a 120-140 mA draw. Bright a few steps away, but too much of its light wasted angling up into the sky and down into the water and too little left in the lateral plane to be useful at distance.
4.Good luck in finding the desired combination of low cost, low mA draw, and 2 mile visibility. My unit at 2 above is as close as I've come and would be even brighter with the latest Luxeon 1.2 watt LED (about 50% increase in lumens @< $7) or, for much bigger $, with a 12v constant I source driving the Luxeon I, or brighter yet, a Luxeon III or V.

Good material, Ron. Thanks!

I was looking at the radiation pattern of the Luxeon Side Emitter and noticed that, "right side up", most of the light radiation is above 90 degrees to the side, the 100% point being about 83 degrees and the 50% points being at about 67 degrees and 96 degrees, from vertical:



I'm thinking that the side emitter might do better in an anchor light application mounted upside down in the top of the light, where the illumination would be something like this (if I've done the math correctly this morning):



Another pro to this is that a heat sink could be mounted on top of the light and more current used. A con would be the shadow of two power wires running up to the top of the light. Perhaps it would be best to use four or more pairs of finer wires spread around the light to carry the current to narrow the shadow on any one point.

Thoughts? Best I can tell OGM uses it "right side up." Am I totally off-base here, or do they use a different reflector?
--
Moe

Moe.....
1. Interesting point on "rightside up" mounting. Had not thot about it, but for simplicity of construction and use, my anchor light and the side emitter therein hang upside down....closed lens end downmost,open lens end up facing, LED extending down from its heat sink, entire unit hanging down from its electric supply wire.....in general like the cheaper version of the Megalight. I had no interest in permanent mast mounting, but rather intended to hoist the anchor light on a halyard when needed and stow it away when not.
2. Also, I adjusted the relative axial location of the side emitter and lens until the brightest light output is substantially planar (90 degrees to the axis of the LED and lens). It would probably a bit brighter if the LED max output were at 90 degrees rather than at 83 or so, but thats not our call, and my relative axial positioning of LED and lens apears to be useable compromise.
Thanks for your comments.
Ron