Life of s/s anchor chain

I just wonder whether the reduced friction actually works against the chain's main purpose in helping to anchor the boat. In a correct anchoring situation there will always be a considerable (deliberately unspecified) length of chain lying on the bottom, and relying on its friction with the mud / sand to ensure a straight pull on the anchor. I've always felt that the comparatively rough finish of galvanised chain helped with this.
 
Difference between tarnishing and corrosion, in my parlance, is largely one of degree.

I would suggest that 316 stainless steel will rarely suffer significant general corrosion in seawater, although there are clearly other forms that it will. Some examples of corrosion types it could suffer from in this context include galvanic, pitting, crevice. These could produce a heavier rust deposit.

If the corrosion product polishes off I would call it tarnishing. If not, then one of the above is probably the cause. Usually a microscopic examination is sufficient - galvanic implies contact with another metal, pitting likely if an inferior grade such as 304 has been used, crevice I think we have covered.
 
Can I ask for clarification on "plastic deformation" pls ?

AFAIR from my OU course in materials, elastic deformation is when e.g. steel deforms and recovers its original shape.

"plastic deformation" is when the metal changes shapes under e.g. bending or tension, and then doesn't recover.

My concern is that a stainless chain could - under heavy load - undergo elastic deformation, and then if overloaded, experience plastic deformation. At that point, do its properties (breaking strain, fracture resistance, etc) alter markedly, and would a chain have to exhibit visually checkable deformation before it became prone to failure ?

FWIW, I use galvanised chain, but have stainless connectors /forums/images/graemlins/blush.gif
 
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"Generally" perhaps the people who argue against stainless chain are similar to those who argue against the new generation of anchors - Wasi, Rocna, Manson etc.

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Without seeming to be rude ............. rubbish.

Do you really argue with the logic of visible detrioration of galvanized vs no warning Stainless ? Sorry but Galv. chain is easily seen to past it's prime ... stainless cannot. You will NEVER know when stainless is to fail.

If stainless was the answer to the problem - why don't commercial operators go stainless ? maybe it's because life depends on identifying possible failures.
Lift keel wires ... why specify Galv ... lets go Stainless wire ... Yes - you may but not me. I would prefer to see it deteriorate and change than think it's fine because it has no visible deterioration.

Dear oh dear ..............
 
Has any forum member ever had a stainless anchor chain fail on them? We have all heard rumours but I have never met anyone who has had this misfortune. I personally think the risk is very small.
 
Probably not valid because how are you going to find same number of Stainless chain users to galvanized to make fair comparison ? How many carry all stainless anchor sytems - very few I would suggest.
 
That's an interesting point! I have never heard of a stainless chain failing either, I'd be very interested to know if there are any confirmed instances.

But I am still none the wiser as to a probable lifespan, just to try and make an evaluation how long would you expect a ,well maintained, galvanised chain to last? Or is that an impossible question to answer?

www.gerryantics.blogspot.com
 
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That's an interesting point! I have never heard of a stainless chain failing either, I'd be very interested to know if there are any confirmed instances.

But I am still none the wiser as to a probable lifespan, just to try and make an evaluation how long would you expect a ,well maintained, galvanised chain to last? Or is that an impossible question to answer?


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My galv. system is in its 10th year of service with me ... that's chain and rope as well as shackles / anchor ... and they were with boat when I bought it. I have no plans to change any of it in near future. Boat is mid 70's and I suspect I may have original gear ...
 
Both stainless and galvanised should last 'for ever' in the context of yacht equipment. With galvanised you'd have to re-galvanise every 6 to 10 years if it is used regularly, and with stainless you ought to inspect for corrosion. Obviously if you have used the gear in very extreme conditions - hurricane, etc. - you would want to check it even more carefully.

Stainless is the way to go if you can afford it -- though you need to be aware of the danger of crevice corrosion but that applies to all stainless used in load bearing or safety critical applications.
 
Our stainless chain snapped last night in 35 knots wind. At midnight..I was asleep. Probably one of the most challenging situations Ive ever had to deal with. Amazingly we didn't hit any thing and no further damage. But confused as to why. It looked good, and correct rating for the boat
 
lawrie909 said:
Our stainless chain snapped last night in 35 knots wind. At midnight..I was asleep. Probably one of the most challenging situations Ive ever had to deal with. Amazingly we didn't hit any thing and no further damage. But confused as to why. It looked good, and correct rating for the boat
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Can you provide a clear, in-focus photograph of a fracture face please? Assuming the broken bits were saved. What material was the chain?
 
lawrie909 said:
Our stainless chain snapped last night in 35 knots wind. At midnight..I was asleep. Probably one of the most challenging situations Ive ever had to deal with. Amazingly we didn't hit any thing and no further damage. But confused as to why. It looked good, and correct rating for the boat
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How d you know it was the correct rating for the boat? What 'sort' of boat do you have what chain is rated for your boat? Chain, when supplied professionally, should come with a size and a steel grade, G3 or 30, G4 or 40 (in America G43) or G70. Some G70 (USA) is marked with the WLL. America, Imperial, chain links are longer than metric chain. Chain might be marked with size, say 5/16th or 8 (for 8mm). But most anchor chain is not marked at all!


Stainless steel comes in a number of forms, 316, 304 and Duplex being some of them. If the chain is duplex it will probably be marked as G60 with some form of makers mark, commonly the initials of the company. If its 316 or 304 is might be marked as such. Not every link will be marked - you would need to look at every link carefully over a 1m length. If its not marked - it should have been retired as soon as its anonymity was identified.

How the membership here is meant to offer sensible comment in the absence of knowing what grade of steel is being discussed is a mystery.

Stainless chain is usually so expensive the receipt for same will be in the yacht paper work - what does the receipt define the chain as?


An entrepreneur here 'found' some beautiful stainless chain. He thought to market it (as anchor chain). I tested it for him. It did not break - but stretched and stretched and stretched. It failed because it distorted so much and would not have fitted the appropriate gypsy. Another good idea that went into the bin. This amazing yield, of stainless, is not restricted to chain. I've tested shackles (no makers mark nor name) where the shackle pin has squeezed, like toothpaste out of a tube, through the shackle eye. The stainless has not failed (broken) but the yield has been so high that the device deformed and became unusable.

Jonathan
 
I have always used galvanised chain & in the past have had it regalvanised. Today the costs are simply too high.
So stainless is attractive, but my worry would be how would you know what grade stainless you are getting?
We know 316L is going to be the best grade but if you got palmed off with 303 or 304 would you know until a few years down the line? As ever Caveat emptor!
 
My experience has been with stainless steel of some sort used on a swing mooring. it came from a cement factory rotary kiln so SS for heat resistance I would think. The chain has round links of about 12mm wire diameter. It has 2 cheap SS shackles in circuit of 10mm size. It also has a ss rod through mooring buoy with built in swivel of I think 12mm size.
The thing is this set up has been down for what must be 20 years. No sign of wear on components unlike Galvanised Iron (GI) previously used which did not last more than 2 years. Certainly in the past any use of GI wearing on ss was a place for rapid wear.
There was a case where one top link corroded seemed like from inside out (you would think it torredo worm) So I keep an eye on all the rest but no more sign of this problem. The chain is over rated for the purpose so even with this corrosion it was not near failure. It is mandatory for the mooring to be inspected professionally evey 2 years coming with a 12 month guarantee.
So this experience is probably of no help to OP whose ss chain will be much closer in spec to actual worse case loads so more concern. But I love my ss mooring chain. ol'will
 
The risk with stainless steel in many things is that folks think it lasts forever. For most chain, crevice corrosion is going to be very slow. Same with chain plates. If the chain were galv, the owner would replace it when it gradually got shabby. With stainless, unless you really inspect it, link by link, it looks really good until it fails. The same is true of most stainless hardware. I think we've all had SS hardware crack.

The result is that a stainless chain will have a longer life that galv, for most of us, but not THAT much longer. Leave it in a wet locker for 20 years and it will still look pretty good, but at that point, probably not at all trustworthy. Just remember to replace it at 5-7 years, and to inspect sections of links very closely, perhaps every other year.

Something like that.
 
Our SS chain is hanging up in the garage right now. My theory says that’s better than a damp anchor locker over winter, and also makes sure I clean the locker. But that’s easy for me, we are a chain/rope boat, there’s only 10m of 10mm chain. This thread has reminded me to inspect it carefully though
 
Chiara’s slave said:
Our SS chain is hanging up in the garage right now. My theory says that’s better than a damp anchor locker over winter, and also makes sure I clean the locker. But that’s easy for me, we are a chain/rope boat, there’s only 10m of 10mm chain. This thread has reminded me to inspect it carefully though
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10m of an unknown supplier of an unknown quality of chain in, say, 100m of mixed rode makes the stainless the weak link (as the textile is probably of local origin). The stainless is a small part but is the weakest link.

There is a quality and reliable source of G60 Duplex stainless, in Kitten Waelder. Maybe explain why, if you feel the need to Molly coddle your 10m length of nefarious SS chain, explain the logic behind why you did not go to the known and acknowledged reliable source - its only 10m.

You presumably insure Chiara, its a source of pleasure to you - but you risk it all in using a cheap bit of chain.

I question the executive thinking.

Jonathan
 
Neeves said:
10m of an unknown supplier of an unknown quality of chain in, say, 100m of mixed rode makes the stainless the weak link (as the textile is probably of local origin). The stainless is a small part but is the weakest link.

There is a quality and reliable source of G60 Duplex stainless, in Kitten Waelder. Maybe explain why, if you feel the need to Molly coddle your 10m length of nefarious SS chain, explain the logic behind why you did not go to the known and acknowledged reliable source - its only 10m.

You presumably insure Chiara, its a source of pleasure to you - but you risk it all in using a cheap bit of chain.

I question the executive thinking.

Jonathan
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I dunno. I bought it from a reputable supplier, not some manky Chinese bucket shop. 10mm ISO4565 G4 Stainless Steel Calibrated Anchor Chain - per metre
 
1 reported failure in the 17 years this thread has been running, with many anchor hours in stainless chain in that period, suggests no one needs to worry about it, everything else being equal.
 
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