When to replace anchor chain?

doug748 said:
When on a swinging mooring, I used to lash the locker open when heavy rain was forecast - not an unusual event in Plymouth. -)
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Don't forget that many older boats do not have self draining anchor lockers ... ie my Sunrider - the chain passes down to the bilges in the bow. Through holes in the bulkheads allow water to drain back to main cabin bilge where the auto-bilge pump takes care of it. I only have the 'Naval Pipe' on deck ...
 
doug748 said:
When on a swinging mooring, I used to lash the locker open when heavy rain was forecast - not an unusual event in Plymouth. -)
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We occasionally get 'liquid sunshine' on the West Coast. :D
I think it would need really torrential rain to wash the salt out of a heap of chain. I suspect that an average day's rain would only dampen the chain, and reactivate the salt. Anyway, our chain is used every day that we're sailing, and with a good deckwash hose, it gets stowed clean, but wet.
 
It also works well in the winter when I give it the open hatch treatment for a month or so, another reason not to have rope, which is fine in it's place but I was glad to be rid of it for 100% chain
 
Like Refueller, I only have a hawse pipe on deck, and any water that finds its way below ends up in an undrained bilge. My chain maintenance master plan is to pull the whole lot out and leave it on deck for a few wet weeks in winter which, apart from the rope-chain splice, seems to work. TBH, I'm not sure anything would work for the splice; seawater soaks right in and I doubt if a hosing down or leaving in the rain, even on a weekly basis would get get all the salt out.
 
The other practice worth following is when you leave the yacht for the winter (those whose year of sailing is only 6 months) then take all the chain out, wash it with fresh water, and leave, flake, on a pallet to drain (under the hull). Try not to leave it in a big heap - pay it out neatly. If you worry about someone stealing the anchor - take it off.

I recall Vyv, sorry to quote you again, leaves his chain festooned over the cradle or supports for his yacht when on the hard - a bit like a laundry line (Irish laundry?)

Rust at the splice of a mixed rode - accept it as part of nature's intent to have you practice splicing. Cut the short length of chain (and rope) off - resplice.

If you look at your chain and it is covered in a white deposit - that's white rust. Its your galvanising slowly dissolving (google 'white rust'). Its a salt of zinc, zinc hydroxide or carbonate - it develops with fresh water in a damp environment (you don't need mud or (much/any) salt for it to develop - just water.

Leaving you chain in a damp locker in the presence (or absence of salt and mud) is a recipe for a shorter chain life. Of course if you have won in the lottery, have been bequeathed oodles of cash - it might not matter - so why bother.

Its not difficult to take care of your chain and give it the help it needs. You take your sails off over winter - why not treat the chain similarly (it, or the galvanising, is also a consumable).

If you live on your yacht at anchor - expect the galvanising to fail - it does suffer from abrasion - it will not last forever. One of the unknowns is how long does galvanising actually last when used on an 'average series of seabeds' - how many years.

The expectation seems to be, maybe, 10 years - I think this unrealisitic. I have an abrasion test where I allow short lengths of chain to rub on the seabed (I hang them from the transom of our cat on its swing mooring (silica sand seabed, short steel beam, short lengths attached to beam)) - I can see clean metal after 1 month! My samples are of course on the seabed all the time, whereas an anchor chain 'lifts' - Some chains last a bit long, 2 months. Its a comparative test - it does not necessarily represent 'real life' - its as close as I can get - and better than gut feel.

Jonathan
 
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thinwater said:
I wonder how many of us measure a length (say, 40 links) of chain when new, so that we can gauge when it has stretched do to wear or stress?
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Not me.

However I do have some original uncoated chain and a few short lengths, about 150mm each, of freshly coated unused chain that I am holding as standards. When the chain was coated I attached, with wire, links that I had ground flat (so half of a complete link) along the length of the chain so that I could measure coating thickness achieved (its not very accurate to use a coating thickness meter on a curved surface) and ensure the coating was similar along the length of the new rode. My chain is 6mm and a second rode, 8mm, has been made, same coating technology, and we followed the same practice (and I kept and used some of the 8mm chain to use in my abrasion tests).

For completeness both rodes, 6mm and 8mm, were tested to break, Ultimate Tensile Strength - and could be certificated for strength and the thickness of galvanised coating (it seems so simple - why don't chain makers/retailers do it?)

I used some of these short lengths of chain in my abrasion tests, see post above comparing size of chain, hot dipped galvanised (HDG) coating (normal gal) and Thermal Diffusion Galvanising (aka Armorgalv - there are other TDG processes).

Chain size has no measurable impact on abrasion - in practice smaller chain may enjoy less abrasion (because it is on the seabed for less time) and TDG has greater abrasion resistance than HDG and can be applied with a fairly accurate coating thickness. The TDG chains with which I have been involved has been applied with a coating 20% greater than that specified by the US Navy.

Jonathan
 
When new (galvanised) chain is used, the apparent length of a given number of links will quite quickly increase, as the relatively soft zinc smooths and wears. That would tend to make a length comparison meaningless. I have just had my chain regalvanised. No spinning involved, just hot dipping and shoogling, so there is a lot of zinc, at least some of which will be on the bearing surfaces between adjacent links.
 
I do like a bit of chain shoogle :)

Not a term I have heard, or read, for decades.

All is not lost

I think, with your frequency of anchoring, the soft zinc will have worn off, completely, on the working part of the chain by the end of the summer - leaving the hard and abrasion resistant zinc/iron alloys (on which you depend) - and you can measure it then.

What sort of life did you get from the previous galvanising.

In order to stretch your chain, or for anyone to stretch their chain, you need to have it under tension at more than 2 times WLL - I hope no-one on this forum is subjected to such conditions - ever.

Jonathan
 
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