"Calif Bill" wrote in message
m...

"Richard Casady" wrote in message
...
On Mon, 28 Jul 2008 17:40:29 -0700, "CalifBill"
wrote:


"Short Wave Sportfishing" wrote in message
...
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?

How about adding some zincs?

These are galvanized bolts. Adding zinc to zinc will accomplish
little.

Casady

The zinc on those bolts was long gone.


So.... the zinc is just a coating and not mixed into the steel bolts?