On Mon, 28 Jul 2008 20:14:30 GMT, "Chuck" wrote:

I know... I only post when I have a problem. This happened two weeks ago.
The bolt on the front outer piling holding the boat lift cradle pulley
sheared right off and the boat went in the drink. Photos of the boat, the
bolts, and some telltale corrosion streaks are stored at the links below.

www.thespaceexplorers.com/corrodedbolts3.jpg (boat in water)

www.thespaceexplorers.com/corrodedbolts1.jpg (3/4 galv. bolts corroded away
to nothing)

www.thespaceexplorers.com/corrodedbolts2.jpg (bolt rust stains on pulley
housing)

OK. So my question is.......... is there any way to diagnose a galvanized
bolts integrity before it rusts through like this again? I can't seem to
find my portable X-ray machine. I also can't quite figure out how to do a
simple swapout on the other three. I don't know anybody who swaps their
lift bolts out every few years!

I'm probably wrong, but that looks like electrolysis. Which means
that you have some kind of current leakage somewhere - maybe from a
shore charger?

Is your boat isolated from shore side current?