"Dazed and Confuzed" writes:

What do you do when the boat is unattended if you don't have a level
switch?

Close any open seacocks when leaving the boat for extended periods.

And what do you think about an electronic level switch?
snip
What technology?

Capacitance, hydrostatic, and vibration are all possibilities, and all have
a down side.

Vibration would be my choice since it is not affected by conductivity or
lack of it.

Having said that, sloshing around will be a major problem. Level switches
like steady state conditions.

It's a bigger engineering problem than it's worth IMHO.

Having an automatic pump on an unattended boat can get VERY expensive.

As an example, spring a fuel leak and allow 10-20 gallons to drain into the
bilge, then pump it overboard while the vessel is unattended.

Need I say more?

HTH


--
Lew

S/A: Challenge, The Bullet Proof Boat, (Under Construction in the Southland)
Visit: http://home.earthlink.net/~lewhodgett for Pictures