Now I understand, the Davis Mini-Mega light (it sure is Mini and a long way from Mega). For a while I thought it was those units that took a 6 volt lantern battery in a white base and had a big rubber donut connecting a fresnel lens on top.
I had one of the Mini-Mega thingies and found it so weak as to be useless as a serious anchor light. Perhaps in a popular anchorage they would be OK. Fresnel lenses are a mixed blessing. Try taking one below in the cabin and look at the light pattern. If the light source is perfectly centered there will be a flat disk of light around the lens with the lens at the center. If the light source is displaced up or down the disk will become a cone. For a fresnel lens to be effective the disk (or cone) of light must hit the observer's eye, if it doesn't it is worse than a plain lens. This is why motorboats can use them for running lights and sailboats must not. When the sailboat heels, one running light's radiant disk will be up in the air and the other down in the water. Except for dead astern, the same for the stern light. I wish the CG would use plain lenses instead of fresnel lenses in buoys. When the buoy is bobbing around in seas you have to be close or lucky to have the light disk hit your eyes the same time the light flashes. The anchor light is a major safety device. It does not pay to economize here. A few years ago two men were anchored in Fernandina Beach with no anchor light. They dragged anchor into the channel and run down by a barge that did not see their boat until it was too late. At least one died, maybe both. I'm sure it has happened more than it should. Get a first class automatic anchor lamp, like Ken makes, and put it in a sturdy fixture so you can sleep in peace, even when the weather makes up. As to location: on a sailboat I don't like the mast-top lights, they are not where one normally is looking and they tend to blend in with the stars. The forestay is a good location if you keep it from flopping around to prevent the wires from breaking, perhaps on a short staff in a lifeline socket or such on deck. That's where I have my anchor day signal, but put my light on a mast on the wheelhouse. I suppose ideally two anchor lights like two steaming lights, one on each side of the mast down low, would be best. Norm S/V Bandersnatch Lying Julington Creek 30 07.695N 081 38.484W > [Original Message] > From: Ken James <[EMAIL PROTECTED]> > To: <[email protected]> > Date: 10/14/2008 10:06:57 PM > Subject: Re: [Liveaboard] Anchor Light Location > > > > Ed Kelly wrote: > > Those little DAVIS lights with the Light detecting diode make it > > easy to have two, and just leave one up on the boom (or my > > preference - on the line to the front furler) all the time at anchor > > and let it go on and off with the sunset and sunrise automatically. > > The Davis lights use a cadmium sulfide light > sensitive resistive type photo cell for light > detection, not a photo-diode (so I am a bit nit > picky maybe ;-) ). The function is similar but > will use a bit more power than a diode. > The Davis lights also use an incandescent bulb for > the 'anchor light' function (some Davis lights > also use leds but not for the main light). > For the same amount of power used by the light as > the Davis you can get an LED anchor light 'bulb' > that also has built in light detection and will be > far brighter and last longer. > For a comparison photo of a Davis light and an > older led anchor light model in the late evening > see www.firststarled.com -Ken > _______________________________________________ Liveaboard mailing list [email protected] To adjust your membership settings over the web http://www.liveaboardnow.org/mailman/listinfo/liveaboard To subscribe send an email to [EMAIL PROTECTED] To unsubscribe send an email to [EMAIL PROTECTED] The archives are at http://www.liveaboardnow.org/pipermail/liveaboard/ To search the archives http://www.mail-archive.com/[email protected] The Mailman Users Guide can be found here http://www.gnu.org/software/mailman/mailman-member/index.html
