Tuesday, June 7, 2011

Anchor Lights

The sailing vessel Valhalla has some interesting ideas for those anchor lights we like to put lower down on our sail boats. He writes...
VALHALLA, like most cruising boats, has an anchor light at the top of the main mast.  Though in full compliance with the Colregs, it is NOT the best situation for two important reasons:

1.  The bulb consumes 20 watts which, at 12 VDC, draws 1.67 amps ... an excessive amount of power.
2.  The light is too high for easy recognition by small boats moving around an anchorage, and can be mistaken for a star or planet due to the elevation!
There are now low powered LED navigation lights on the market which range in price from US$ 100-250.  A bit pricey for the budget. 
My first solution was to use a utility light (Davis Utility Mega-Light)  hung on the flag halyard, below the spreaders. This light has a photocell switch and, with the most efficient of two supplied bulbs, reduced the amperage draw to 0.11 amps.  A further reduction in power was to build a new bulb using the base of a burned out one.  Four white LED's (which have a drop of 3 volts at 20 ma) were soldered in series and positioned to face 90 degrees apart.  The leads were secured inside the bulb with a small amount of epoxy putty.  The current of 0.02 amps was negligible while giving sufficient brightness at a cost of US$0.50.

The Davis utility lights have a short (6 -9 months) life span due to UV deterioration of the plastic housing which soon cracks and allows water to flood the unit and short out the circuitry.  That is unless the photo cell circuit quits working first, which also happens.
To build my own, I salvaged the fresnel lens from the failed unit, built a photo cell circuit (again with 4 white LEDs) and, with a plastic cover (it is the retaining knob for a household fan!), used silicone to seal everything.
So far it has outlasted the Davis lights ($39.99)!

While cruising in Malaysian waters we noticed that numerous fishing boats used flashing lights ... of many different colors.  Their nets were sometimes marked with flashing lights as well, though not often enough for our satisfaction.  Browsing the fishing supply stores we found numerous models of small flashing lights, both incandescent, strobe, and LED.  These lights are powered with either one or two flashlight batteries and incorporate a photocell switch.  After trying several brands I found one that has blue LEDs, runs on two batteries and last about three weeks.  The price we paid was RM18 (US$ 4.75). 
Here's one undergoing 'trials' along with my 'home brew' white anchor light.

The markings on this light are:
Yang Cheng
Made in China

The colored dot indicates the light color, in this case blue.

To avoid the use of flashlight batteries I constructed a simple voltage reducing circuit (one IC 7805 and three diodes 1N4001) to reduce 12 VDC to 3.2 VDC.  The circuit board and components fit inside the light housing with a power lead to the boat's batteries.  The low power consumption obviates the need for a heat sink.

The blue flashing light is now mounted just beneath the white one.  If we were to make an addition to the navigation light memory phrases, such as 'red over red the captain is dead' for a vessel not under command, ours would be 'blue under white that's our boat all right'!  Very useful after an evening ashore while finding your own boat in a dark and crowded anchorage !!!!!


  1. This anchor lights looks cool. Such a interesting and attractive night lights. Keep posting such post.

  2. Dubai. That's an interesting place I would love to visit. Thanks for looking and your comments.


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