Stainless Steel anchor chain

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Neeves

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Stainless steel gets a very bad press as an anchor chain but the term 'stainless steel' is ubiquitous meaning different things to different people.

So focussing a bit does anyone have any comment on Ketten and Welder's Cromax stainless steel chain. G60, so twice as strong as G30 (made to minimum standards), its slippery, so suggested it will not tower in the locker, its smooth so is again said to be cleaner. If you had a very swish yacht it would be very pretty (and match a nice stainless steel anchor) It is expensive, very - but if you lived at anchor and you needed to replace, say, G70 chain every 4 or 5 years it might be economical. Being G60 instead of, say 10mm gal, you could use 8mm Cromax, saves some weight as well.

But does anyone have any experience of using it? (or even heard of it being used?) Or is it all about bling?

Jonathan
 
Very droll, difficult to compete with all this wit, being rather late here.

Tomorrow I'l be all bright and shiny :)

But does Duplex work harden as 316 does? I have no experience, particularly of duplex stainless :(

Oddly given how much stainless costs I see quite few yachts with stainless chain - and I bet its 316 (though I'm not into betting). I see lots of stainless shackles joining gal chajn to gal anchors (and Vyv has no issues - see the shackle thread). I know the armchair experts scorn stainless (as would I but mainly because of alternatives), despite the numbers of shackles, swivels and lengths of chain - so I pondered Duplex, which I know nothing about.

Jonathan

So I'll go to bed and see what further insights develop overnight :)
 
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I have had an email from my contact at Petersen after Monday's discussion about the 17/4PH shackles. (He is evidently a keen reader of the forum now!) They can supply the Cromox chain made by Kettern and Welder in Germany and are considering listing it on the website spars.co.uk. He tells me that the chain is proof tested in the machine, which I understand is also the case with the best Chinese chain, also made on German machines.

The link to the makers is at http://www.cromox.eu/en/ It seems to be made in 318LN, which is a duplex stainless steel. Answering Jonathan's question, yes it does work harden, probably to a greater extent than 316. I would expect its strength to be somewhat better than 316L.
 
vyv_cox said:
... Answering Jonathan's question, yes it does work harden, probably to a greater extent than 316. I would expect its strength to be somewhat better than 316L.
Click to expand...

So how big an issue is work hardening of ss chains in an anchor rode ? I assume that the snatching loads that are likely to be present in an anchor rode are likely to be an issue but can you quantify the percentage strength reduction that might be expected to occur ?

Thanks,

Boo2
 
The only major purchase regret of my 5 years of owning a project boat was that I replaced the 35m rusty chain with 60m of normal galvanised for about £700 instead of spending over £2k on stainless. It's slinkiness would have saved me hundreds of times having to poke the chain to make it stow every coupld of metres. And I could have fitted in another 20m into the big drop space I need to leave to make it store at all.

I know I should bite the bullet and throw away the newish chain for stainless but that waste of money doesn't feel right either.
 
Neeves said:
Stainless steel gets a very bad press as an anchor chain but the term 'stainless steel' is ubiquitous meaning different things to different people.

So focussing a bit does anyone have any comment on Ketten and Welder's Cromax stainless steel chain. G60, so twice as strong as G30 (made to minimum standards), its slippery, so suggested it will not tower in the locker, its smooth so is again said to be cleaner. If you had a very swish yacht it would be very pretty (and match a nice stainless steel anchor) It is expensive, very - but if you lived at anchor and you needed to replace, say, G70 chain every 4 or 5 years it might be economical. Being G60 instead of, say 10mm gal, you could use 8mm Cromax, saves some weight as well.

But does anyone have any experience of using it? (or even heard of it being used?) Or is it all about bling?

Jonathan
Click to expand...

We live “at anchor “ as you say and have to buy new chain every 4 to 5 year.
Just bought 50 meters which I then connect to the best 20 meters of the old chain.

I noticed that the first 10 meter behind the anchor are ok, then from 10 to 30 meter the chain is worn. Original 8mm is at the linking points 6 to 7 mm.
( This is also why the chain starts to turn )
Logic. The chain closest to the anchor lies on the bottom, then, depending on the depth, the chain has to support its own weight and moves all the time.
I would not be surprised that a SS chain would be worn more or at least the same.
So your argument that SS is better for a live at anchor boat could be wrong.

BTW, we wintered the last years in the Poros Saronic area, and I have a suspicion that the volcanic bottom also helps wearing the chain down. Methana, just a few minutes away is known to “Eat “ galva from chain in days.
 
Boo2 said:
So how big an issue is work hardening of ss chains in an anchor rode ? I assume that the snatching loads that are likely to be present in an anchor rode are likely to be an issue but can you quantify the percentage strength reduction that might be expected to occur ?

Thanks,

Boo2
Click to expand...

I would not expect it to be an issue at all but Jonathan asked the question. 'Work' in this context means plastic deformation, not a problem normally encountered in chain. The proof load on well-made chain is twice the WLL, or half the MBL. For 316 chain I would expect the proof load to be slightly above the yield point, which is a very low proportion in these alloys, so there might be a small amount of deformation as a result of the test. For 318 the proof load should be below the yield point. In practice these are very high numbers, around 2 tons proof load for 8 mm chain, most unlikely to be encountered.

Work hardening is also 'work strengthening' of course. Many 300 series items on the boat are manufactured by cold drawing, stamping or rolling to increase their strength, first and foremost wire cable and their fittings.
 
RupertW said:
The only major purchase regret of my 5 years of owning a project boat was that I replaced the 35m rusty chain with 60m of normal galvanised for about £700 instead of spending over £2k on stainless. It's slinkiness would have saved me hundreds of times having to poke the chain to make it stow every coupld of metres. And I could have fitted in another 20m into the big drop space I need to leave to make it store at all.

I know I should bite the bullet and throw away the newish chain for stainless but that waste of money doesn't feel right either.
Click to expand...


Definitely go for the stainless, and then to ease your conscience I will accept your nearly new galvanised chain to save you a trip to the dump with it!
 
KellysEye said:
When we were Trinidad there was a yacht anchored that broke loose because of crevice corrosion in the stainless chain.
Click to expand...

On the face of it that's quite surprising ? Doesn't crevice corrosion require anaerobic conditions to occur ? I suppose if the anchor buried itself deep down in mud the conditions could be anaerobic, what were the circumstances in the case you refer to KE ?

Boo2
 
vyv_cox said:
Where are the crevices in chain?
Click to expand...

I had a bolt fitted through a tubular cockpit cover frame corrode through crevice corrosion. The only this could have happened was having salty water laying in the interconnection. This could happen in a damp anchor locker with salty water retained where the links come together and the atmosphere in the anchor locker preventing the water drying out.

As far a work hardening polishing stainless also work hardens the surface and drilling a hole letting the drill rub rather than cut will also work harden the hole.
 
Don't look @ the site for 96 hours and such a new exciting thread starts and nearly finishes, before I read a word.
When next my 8mm chain needs replacement, I'll be there to get 80m of 6mm Cromex.
This could be quite a long time though, I've just end-for-ended my 2002-replaced chain and would confidently expect a similar life out of the revised layout - 2029.
I certainly don't anchor all the year round, but do for most of the 6 months p.a. I'm on the boat.
So how long would the superior Cromex chain take to recoup its cost?

Original chain 8mm bought from Bradleys' Cradley Heath, made, certified and galvanised in UK. It has, in fact, outlived a CQR anchor, which developed a badly worn joint and had already been re-galvanised twice.
No problem with chain piling - but then I'm single-handed and only have an SL Anchorman manual winch . Though I confess to having used a WinchRite power handle for the first 3 months of last season, until the gearbox broke. Fantastically quick and trouble free.
The Ultra (and Mantus) SS anchors, and chromex chain, like the McLaren P1, Porsche 918, LaFerrari or Lamborghini Avventura, remain out-of-reach (and probably irrelevant) exotica.
 
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