On Mon, 6 Aug 2007 16:55:40 -0400, "Roger Long"
wrote:

So Larry, what would you recommend for this MOB application?

I have one of those plastic mounted magnetic switches used on windows in
burglar alarm set ups epoxied into the pole. The magnet is glued into a
Velcro strip with a line to the boat. When the MOB pole goes overboard, the
magnet stays behind and the light goes on. Perfect - except for reed
switches being unreliable.

What would be flush, watertight, and reliable?

There is a reed switch - a mercury wetted reed switch - which is less
bad than most - though environmentally suspect.

Brian W