Rusty Anchor Chain ?

My anchor chain is rusty yet it does not appear to have lost thickness. I do end for end it occasionally. I've read that there is approximately one tenth the amount of metal lost as compared to the amount of rust. How do you determine when the chain is at the end of its usable life?

When you can no longer keep your decks clean.

Well, there are two considerations: how much metal and strength is lost to rust and how big the chain is in relation to your anchor loads. 1/4" G4 and 3/8" BBB have approximately the same safe working load limit- about 2,600 lbs and 5/16" G4 is about 3,500 lbs.

Most cruisers would use 5/16" G4 for your size boat.

Yes, I agree that rust will expand to about ten times the metal lost. So scrape off a piece of chain that is typical, down to bare metal and measure the link diameter. Then compare against new dimensions.

Note that 1/16" of diameter lost on 5/16" G4 will result very approximately in 35% loss of the original WLL as the WLL is related to link area, not diameter. If you have lost that much then I would replace it.

And finally consider that galvanized chain loses no metal to corrosion until the galvanizing wastes away. So you may want to start again with new chain.

David

Howard,

'Magic' is a very very nice boat. In my biased opinion.

If the chain is rusty, and you anchor out, then get a new chain. I would. And you will sleep better when on the hook.

Just saying...

H.

Interesting replies. Thank you. FWIW, the chain is 3/8 BBB

My chain had surface rust, enough to make a mess of the deck but little link corrosion as far as I could see. It is 5/16 BBB. I was going to replace with longer G4 chain, but getting a drum of new chain to the slip, or anywhere else convenient, was going to be a big PITA.

So I end-for-end the existing chain. The bitter end had a fairly good amount of galvanising left. Prior to putting it back in the locker I ran it through a bath of phosphoric acid and when dry painted the whole lot in 10 m increments.

I'm hoping to avoid rust until next year's haulout when I'll be able to drive a drum of new chain up under the bow for hauling aboard.

That's one good looking anchor chain.

hmason said:

That's one good looking anchor chain.

Click to expand...

I agree with Howard

Timely post .
I just this week inquired about re galvanizing my 100meter x 8mm short link chain and to my surprise the cost was 20% of replacing with new chain .

Greetings,
Mr. I. Rasta chain!

Had my 3/8" BBB chain as well as my 40kg Rocna re-galvanized in 2014. Cost was $900 and change. I also used the pickup truck under the bow method while the boat was on the hard, worked great for both directions! My 400 ft of 3/8" weighs 668 lbs. so handling it is a The galvanizer was in VA, Southern Galvanizers IIRC. Not particularly inexpensive, but not as costly as replacement! I end 4 end it every 2-3 yrs. It can be hard to find a galvanizer who will do chain.