"John H." wrote in message
...
On Mon, 28 Jul 2008 18:11:25 -0700 (PDT), "
wrote:

It could also be a case of disimular metals causing this accelerated
corrosion.

Marty

On Jul 28, 4:14 pm, "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)

http://www.thespaceexplorers.com/cor...olts2.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!

Chuck

I wondered if there might be a reaction between the zinc coating and the
chromium copper arsenate in the treated lumber. Lo and behold:

http://www.fpl.fs.fed.us/documnts/pdf1987/baker87a.pdf

Look at the comparisons between galvanized, aluminum, and stainless steel
rates of corrosion when in treated wood.

That was a good reference. To catch everyone up, YES it is in sal****er.
As far as electrical isolation from shore power, I leave the circuit breaker
for the lift powered at all times since I use the lift a lot. The boat
itself is never connected to shore power. I never leave any part of the
boat or lift hanging down in the sal****er. That last photo of the
new-looking piling was from a neighbor lift where I am now visiting. My
actual one is older and worse looking.

On the other piling, I am going to put a strong lagbolt down the top end and
attach one end of a come-along to it with the other end under the beam
cradle. Then I will try to drive out the bad galvanized bolt with a new
galvanized bold with a thin plastic sleeve on it to isolate it from the
wood. I hate that this happened to me but I guess everyone should take a
look at their own lift situations.

Chuck (another one)