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When to replace anchor chain?

Feb 14, 2014
3,854
Hunter 430 Saba Waveland, MS
Rusty is a good thing, if you keep the water off of it.

A link is made from bar stock and has a 125% over design safety factor.
So measure the diameter of worst link.

Badly corroded links can be replaced
Jim...
PS:
It could also be re-galvanized.
That is for the show room. Zinc corrodes off.
 
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Feb 5, 2004
3,660
Tartan 3800 Westport, MA
Rusty is a good thing, if you keep the water off of it.
Not for steel. This is not a conversion coating.
That is for the show room. Zinc corrodes off.
No, it's not for the show room, it's to protect the steel from rotting away! How long do you think a plain steel chain that's not galvanized would last in salt water? Why do you think that almost all commercial marine hardware is galvanized? And trailers? And steel scuba tanks? Why do you think there are re-galvanizing companies, and that customers pay significant dollars to have chains, anchors, and other things re-galvanized? Wow.
 
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Feb 14, 2014
3,854
Hunter 430 Saba Waveland, MS
I inspected my Rusty 3/8th chain today [changing my Anchor rollers] and made sure my anchor locker drain was open.

No wave action bow spray or rain going to get to my....

Lowest Oxidation State , Fe2O3 [rust], covered chain that WON'T corrode, until I disturb that protective coating.

Boy I am glad that Zinc finally wore off.

18 years of use and minute loss of steel.
_____
Why do you think there are re-galvanizing companies, and that customers pay significant dollars to have chains, anchors, and other things re-galvanized?
Hmmmm?
Stupidity?
______
If you want "pretty", by a Stainless Steel Chain.
_______
I also inspected my Lowest Oxidation State, Anodized Aluminum Mast and Boom.
Nope, no corrosion either.

I wonder why they didn't Galvanize my mast?
Jim...
 
Feb 5, 2004
3,660
Tartan 3800 Westport, MA
"In the case of most low-carbon steel products, iron oxide (rust) develops on the surface and is not protective because it does not form a continuous, adherent film. Instead, it spalls, exposing fresh iron to the atmosphere which, in turn, allows more corrosion to occur."

https://www.astm.org/SNEWS/APRIL_2006/dallynside_apr06.html

You don't galvanize aluminum (your mast) to protect it, it's usually anodized.
 
Sep 11, 2017
149
Beneteau 373 Cape Cod
Jim, you're right about stainless being prettier than non-stainless, but you're dead wrong about rust on chains being a good thing (and wrong about "galvanizing" your mast (unless you have a steel mast, which is QUITE unlikely for what should be obvious reasons). Take a pair of calipers and measure the thickness of a rusty old chain, and you'll see that the steel is getting smaller and smaller as it rusts. The outer, rusty layer constantly flakes/chips/falls off, as evidenced by the rust stains left behind when rusty steel touches anything, constantly wearing away the steel itself. SURE, a little surface rust doesn't mean you need to toss out the whole thing... losing 1% of the steel (strength) in a chain isn't a meaningful amount... but as time goes by, and the rust gets worse and worse, it will eventually rust away entirely. I've literally witnessed chain links that once held 40 foot boats onto moorings, turn into steel links the thickness of toothpicks, and eventually snap. Your disclaimer about not getting it wet isn't terribly useful, since this is a question on a forum about BOATS, and specifically ANCHOR CHAIN. If you're point is "a little surface rust is just a cosmetic issue", I can let that slide. But you'll have a hard time convincing many folks here that "Rusty is a good thing..." and "... keep the water off it" are words to live by in this context.
 
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Oct 22, 2014
9,926
CAL 35 Cruiser Portland OR, moored EVERETT WA
Context.
I think @JamesG161 identified that his anchor locker was dry, not that he was keeping water of his anchor chain.

If he was keeping water off his anchor chain then would he be setting the anchor in the air.

The point as I understand it is that steel chain will rust in time if you use it to anchor your boat. It is not the end of the world. You need to occasionally inspect the chain and if you find links that need replacement then do it. Rust while coating the surface of steel does serve to stop further corrosion in the area it covers. The issue is the rust flakes off exposing fresh steel that will rust and the process continues. You can try to make the steel look pretty with coverings ( paint, galvanizing etc. ). Those are delaying tactics. The covering will crack, chip and flake off exposing the steel and the rust cycle.

To the question posted: examine the chain thickness. Color is superficial. If the chain thickness is less than 50% of the original then you have lost strength in the chain you bought. It is your call. If I want 8,000 pounds holding strength and the 10,000 pound chain strength is 50% corroded I am going to replace the chain.
Good luck @tadd5181
 
Feb 14, 2014
3,854
Hunter 430 Saba Waveland, MS
My last comments.
You guys must think Rusting is a disease that doesn't stop.

Here is what I said.
No wave action bow spray or rain going to get to my..[steel chain]..
If you keep your Anchor Chain "Dry" in storage, then just like Stainless Steel, it forms a oxidative barrier[Rust]...
No more Corrosion.
______

keep the water off it" are words to live by in this context.
:plus::plus:

measure the thickness
:plus::plus:
So measure the diameter of worst link.
:)
_____
Now, if you leave your anchor chain in the water for, say, 5 years, you will find the water wetted part corroding away, the part left to air and the exposed elements, a little worse, and the part in your DRY anchor locker, no more corrosion.
_____
All Metals Corrode in the presence of Oxygen. Stainless Steel too.
Your Anodize Aluminum Mast is pre-Oxidized to make it look uniform and "pretty".
If you knick or scrape the anodized surface, it will corrode too. ;)
I do inspect all my exposed metals every season. I suggest you do too!
_____
Hopefully I am sailing more time, than anchoring.
Jim...
 
Feb 5, 2004
3,660
Tartan 3800 Westport, MA
You can try to make the steel look pretty with coverings ( paint, galvanizing etc. ). Those are delaying tactics. The covering will crack, chip and flake off exposing the steel and the rust cycle.
John, you and others are playing fast and loose with the science here. Galvanizing is not to make steel look pretty, and it won't crack, chip, and flake off. It's a very mature industrial coating technology that is widely used and has stood the test of time.

The zinc protects the steel in much the same way the zincs on your propeller shaft and in your heat exchanger protect them. If you think it's just to make things look pretty, and not effective, why don't you just throw away your prop and hx zincs?

Even if the zinc coating becomes scratched, exposing some steel, the cathodic protection will protect the bare steel.

I must confess I have never read such crap on this forum as people saying that rust will protect steel from further corrosion and that galvanization is for only cosmetic purposes.
If the chain thickness is less than 50% of the original then you have lost strength in the chain you bought.
Ya think? Holy Cow! 50% reduction is something to be concerned about? Who knew? [/sarcasm]

When that galvanized anchor chain gets an overall film of orange iron oxide on it, before it has any perceptible reduction in mass, it's time to regalvanize or replace. Period.

@JamesG161 , maybe you can find a source of plain steel, i.e., non-galvanized anchor chain, and save a few bucks.
Why waste money on stupidity, after all?
 
Feb 5, 2004
3,660
Tartan 3800 Westport, MA
If you keep your Anchor Chain "Dry" in storage, then just like Stainless Steel, it forms a oxidative barrier[Rust]...
No more Corrosion.
B.S. Read the quote and the article from which it comes, that I posted.

Unbelievable.
 
Feb 5, 2004
3,660
Tartan 3800 Westport, MA
@JamesG161 here, I'm going to quote it again:

"In the case of most low-carbon steel products, iron oxide (rust) develops on the surface and is not protective because it does not form a continuous, adherent film. Instead, it spalls, exposing fresh iron to the atmosphere which, in turn, allows more corrosion to occur."

"iron oxide (rust) develops on the surface and is not protective"

Rust is not protective!

Clear yet? Have you ever studied materials science? Have you ever heard of the galvanic series? Understand galvanic protection?

Oh, and by the way, once your anchor chain starts rusting, keeping it dry is not going to help. There's oxygen in air, in case you were not aware.

Here's the article, again:

https://www.astm.org/SNEWS/APRIL_2006/dallynside_apr06.html
 
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Feb 14, 2014
3,854
Hunter 430 Saba Waveland, MS
galvanic protection
Is a different discussion, completely.
That takes place in salty, electron conductive waters.
_____
I am not going there or discuss Science with you, @jviss, or show credentials to win a point.
I offered my knowledge of corrosion, which is extensive.
Bye on this thread...
Jim...
 
Feb 5, 2004
3,660
Tartan 3800 Westport, MA
Bye on this thread...
Good, you've done enough damage here already, with your idiotic assertions about rust protecting steel chain.

FWIW, galvanic protection works in the atmosphere as well as in the ocean. Why do you think they galvanize structural steel, chain-link fences, etc.?

Ha!
 
Oct 19, 2017
4,910
O'Day 19 Littleton, NH
Wow! And here I am missing all the fun.
:wahwah:

Just to add my paltry two cents to this question, I would replace my anchor chain when I can discern a loss of thickness to any of its links.
That's just me. No expertise, no education, no marketing hype. Just my reasoning that I bought a certain sized chain to do a job and when it looses that size, it can't continue doing its job. So err on the side of caution, it's cheaper than the other mistake.

-Will (Dragonfly)