Parallax wrote in message
om...
Practical Sailor had an interesting article about a laser device used
as an alert/locate device for ppl in distress. Basically its a 5 mW
laser diode with a plastic line generating lens. They say that it has
to be held to sweep the horizon and jiggled slowly and that it takes
practice before it is needed. Otherwise it worked great. I imagine
it might be hard for a person in a sinking boat to do this in spite of
practice so why not.........

Mount the laser in a housing with a weight so it always points toward
the horizon. The laser would also be mounted on a flexible rod that
would vibrate at the correct period when thumped by a spring loaded
hammer (a tuning fork like thing).

I have had one of these for over two years. It does not need to be
"giggled" slowly to be noticed. It sounds to me like the person who wrote
the article may not have tested it.

The lens in the device spreads the laser out along a angle (i.e. it draws a
line). The farther away you are from the device, the longer the line is.
At 16 miles, the line is 6000 feet high. The personal ones are about the
size of a AA battery maglight. Our snowmobile club has done some testing of
them, and we have easily seen them at about 15 miles at night with the
unaided eye. If you were in the ocean and somebody looking for you with
night vision, 20+ miles would be no problem at all.

Both the military and coast guard search and rescue are officially using
them. The companies website is www.greatlandlaser.com/

Scott