Corrosion from Galvanized Chain

[hardee]

See how great this sight is: I am learning more "stuff" again. Lots of new research to do, Re galvanizing and cold galvanizing. Not likely to find a galvanizer in our neighborhood but will definitely start looking.

Thanks Dr Bob, Boris, Roger, Warren, DaveS, Joe and all. Looking forward to some new searching.

Harvey
SleepyC

[hardee]

Beautiful day, Been mowing the lawn, need a break (and I'm liking Roger "Dreamer's" idea of chain maintanence more and more). Now back to mowing more lawn , Oh well, beats shoveling snow

I also will be looking into the cold galvanizing process and availability. (Sounds more like a DIY job than the alternatives.

Harvey
SleepyC

[hardee]

**** BRINGNIG BACK AN OLD (2009) THREAD *****

Last season was the first season with any serious anchoring. Most nights out of 6 weeks.

The anchor chain, (1/4" G-4 HT galvanized), did have some lightly rusty sections on it. I used a suggested cure. I found a section of gravel road that was not muddy (as if that would have made a difference) and hooked the chain to the trailer ball and dragged it for about a mile at about 5-10 MPH. That took most of the rust and whitish cover on the chain off. Brought it home and washed it thoroughly in fresh water and have used cold galvanize (rattle can) paint on the rusty sections (still in the process of several layers).

The next step is to mark the chain at several designated lengths. I'm wondering 2 things. If I paint over that cold galvanizing, will it have any adverse affect? AND, what is a good recommended paint for anchor chain?

Harvey
SleepyC

[Marco Flamingo]

I don't know if there is such a thing as a good paint for galvanized metal.

http://www.sherwin-williams.com/homeowners/ask-sherwin-williams/problem-solver/peeling-cracking/peeling-from-galvanized-metal/

Whether paint sticks to sprayed on zinc paint (cold galvanized), I don't know. Probably sticks better with less prep than hot dip, but still sounds like a pain and might not last. The problem with paint is that it will fail while just sitting in the locker.

How many markers do you need? If only a few, I'd use surveyor's tape. Tie it through chain or run it through 3 strand with a fid, leave the ends about 3 inches. Green at 50, red at 100, blue at 150, something like that. Interpolate for 125'. Simple, runs through a winch, impervious to rust, and I've had survey tape stay on for several seasons when run though the winch 50 times a year. Using one color works if you pay attention, red is 50, 100, 150. Simple. And it doesn't decompose in a damp locker.

Mark

[anchorout]

When I was a liveaboard and cranked chain daily, my experience was that re- galvanizing was the only solution to rusted chain problems. If you only anchor occasionally, or don't have a windlass, then the solution can be postponed by cold galvanizing spray or other stopgap methods, but re-galvanizing or replacement is the only real solution.

Galvanizing is worn off chain where the windlass grinds against the outside of the links, but also inside the links, where they grind against each other under load. It is very hard for paint to penetrate these areas. Even so, paint won't last long in these areas because of the constant wear.

Be careful in replacing your chain. As a rookie I once bought "hot dipped" (supposedly) chain at a hardware store. It started rusting after one year. Pay the extra and buy from a commercial marine supply. As someone previously stated the coating isn't very thick, even on good chain. Re-galvanizing will triple this coating.

[hardee]

So, I learned something new tonight. "White Rust". The white powdery coating on the galvanized chain. It is the galvanizing rusting. Once the gavanizing is "rusted through" then the steel can oxidize and rust in the reddish brown we see on bare metal rust.

Harvey
SleepyC

[AstoriaDave]

That white rust, aka zinc oxide, is a sign that the zinc in the galvanized coating is doing its job. Somewhere else on the chain, or on some ferrous metal in conduction with the chain, is an exposed surface where iron would be rusting EXCEPT that the zinc on the chain, being more active electrolysiswise, is "rusting," aka oxidizing, instead. That's why it is refered to as a sacrificial coating. And when it is gone, baby, the chain itself is next!

Yup, same zinc oxide found in ointments used to protect skin from sunburn.

[hardee]

Like the "Zincs" on the boat.

The most regular rusty place on the chain was near the end, where it had been connected to a stainless swivel. That area has some places with some regular rust mixed in with the white rust.

Harvey
SleepyC

[AstoriaDave]

[hardee]

Dave, I'm just guessing here. The Stainless Steel swivel attached between the galvanized anchor and galvanized chain ==> dissimilar metals??

AND the end of the chain at the anchor would get more abrasion from bottom contact, roaming with the angle of pull from the boat, although I would think there would be more length than the 5-6 feet.

Harvey
SleepyC

[teflonmom]

Hi again Tom,
I was reading this anchoring discussion and it rattled my old brain.
The weight of the chain was in the boat when I got it from the dealer. He thought that the boat balanced better with a lot of bow weight. However I forgot that Tom has added some other mods that increased the weight of the boat. To get the RPM up perhaps a prop with a little less pitch would be a help. Other brats will have good ideas as to the size. Tom painted the bottom because he kept the boat in the water. Bottom paint also adds drag, so prop size may be the answer.

Fred Messerly