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.

http://www.thespaceexplorers.com/cor...lts3.jpg*(boat in water)

http://www.thespaceexplorers.com/cor...olts1.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.