rust on chain

Appleyard

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Noticed that about 60mm of the anchor chain is very rusty,rest is in good nick. Should I cut out the bad bit and use a link to join the two ends or leave well alone?
 

Norman_E

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Not an easy call to make. It depends how bad the rust actually is. Surface rust looks bad but does not weaken steel very much. If you can reveal sound metal by wire brushing the chain is probably going to be stronger than any detachable link. In any case if you do cut it and fit a link you will have reduced its strength by quite a bit. If it is your anchor chain and the bad part is near one end you might do better to cut the end off and splice the good chain to a suitable warp. A shorter chain and a good strong length of warp might be better than the whole chain with a weak link in it.
 

ashanta

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You don't say if the chain is conected to a rope?
My view is that the anchor end of the chain becomes rusty well before the rest. Therefore you could cut the rusty metre off and resplice to the rope or just cut off the rusty end and swop ends if i'ts all chain.

regards.

peter.
 

hylass

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Should I use a link to join the two ends?...

Once more I should give my own opinion about those "C" links suggested to join the two ends of a chain..

NONE of them have the same resistance than the chain they must join.. and their resistance is BY FAR much lower than the one of the chain.. therefor my suggestion: " NEVER use a "C" link to join two parts of a chain..
 

Swagman

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[ QUOTE ]
Once more I should give my own opinion about those "C" links suggested to join the two ends of a chain..

NONE of them have the same resistance than the chain they must join.. and their resistance is BY FAR much lower than the one of the chain.. therefor my suggestion: " NEVER use a "C" link to join two parts of a chain..

[/ QUOTE ]

Is this opinion only based on feeling or facts?
Has anyone ever seen such C links fail? Or can provide research material demonstrating such a link is weaker than the chain they join?
As I've seen them sold globally for years, never heard of one failing, and indeed used them myself - it would be interesting to establish the facts.
Cheers
JOHN
 

MIKE_MCKIE

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Not too impressed with the "C" type joining links although I have not used them myself, but I buy LOTS of chain & rigging joining couplers & they are certified for lifting, so they "do what it says on the tin" . If you get a "LOK A LOY" or "HAMMERLOCK" chain coupler, you can be sure of the strength, as they are certified lifting gear. They go from 6 mm upwards. A 6mm one has a Safe Working Load of 1.5 MT, is proof loaded to 3.75 & should have a B/S of 6 MT minimum.
The only downside would be if you use a windlass, as they are about 10% bigger width than the chain size. Not cheap, but then what is these days, and what price safety?
 

jrt

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Surely, in an anchor rode, we are not using the strength of the chain but rather its weight to absorb the wave and wind fluctuations. So the absolute strength of a 'C' link is not critical.
 

Appleyard

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Ok You have convinced me I think I will leave it as it is and keep an eye on it in future. Thanks
 

Swagman

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[ QUOTE ]
Surely, in an anchor rode, we are not using the strength of the chain but rather its weight to absorb the wave and wind fluctuations. So the absolute strength of a 'C' link is not critical.

[/ QUOTE ]

Quite agree. And I also doubt if one would ever get an anchor still holding should a chain ever get bar tight enough to get close to breaking a good chain or a link.

I was only questioning the claimed C link 'weakness' as it seemed to be a strongly held opinion. But since asking if anyone knows of any engineering tests - or has experienced a C link going - and not getting a reply from those with the opinions - I can only assume the views are not based on any factual info.........

Cheers
JOHN
 

hylass

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" NEVER use a "C" link to join two parts of a chain..

[/ QUOTE ]

Is this opinion only based on feeling or facts?
Has anyone ever seen such C links fail? Or can provide research material demonstrating such a link is weaker than the chain they join?

To be more precise:

On the "Plastimo" catalogue

ref: 13251 - "C" link 10 mm : CMU (Max Working load) 1500 kg
ref: 25390 - 10 mm Chain : CMU = 2500 kg

NEVER use "C" links to connect two lenghts of chain..
 

hylass

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[ QUOTE ]
Surely, in an anchor rode, we are not using the strength of the chain but rather its weight to absorb the wave and wind fluctuations. So the absolute strength of a 'C' link is not critical.

[/ QUOTE ]

Sorry JRT, but up to my opinion, you are 100% wrong...

You should have a more precise look at the following Web page:http://alain.fraysse.free.fr

The weight of the chain has a negligible effect to absorb wave and wind fluctuation and this why you should use either a snubber or a Nylon wrap

The strength of the chain is very important as, under dynamic load, peak of force can egal or be bigger than the strength of the chain (that's why you should use a snubber)

As the maximum load of a "C" link is much lower than the one of a chain of a similar size: NEVER USE a "C" link...
 

hylass

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[ QUOTE ]

And I also doubt if one would ever get an anchor still holding should a chain ever get bar tight enough to get close to breaking a good chain or a link.

[/ QUOTE ]
Oh Yes.. no doubt about that.. it is also a fact.. under dynamic load, an (good) anchor will slightly drag and its holding resistance will increase with the speed of dragging.. but the chain will become bar tight and break


[ QUOTE ]
I was only questioning the claimed C link 'weakness' as it seemed to be a strongly held opinion. But since asking if anyone knows of any engineering tests - or has experienced a C link going - and not getting a reply from those with the opinions - I can only assume the views are not based on any factual info.........


[/ QUOTE ]

As I have given very precise figures showing that "C" links are much weaker that the chain they should connect.. and this is also obvious when you will look carefully at the design of those "C" links.. in at least two points, the cross section of the "C" links is only HALF the one of the chain.. then?? How those "C" links could be as strong as the chain??

Therefor: NEVER USE "C" LINKS...
 

Ships_Cat

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While I would not use the C links myself, if they are rated at 1,500kg then they are rated much higher than a yellow or blue pin individually tested galvanised lifting shackle's WLL and 2 - 3 times stronger than the WL of a common galvanised shackle bought off the shelf (which is what most people probably use for chain to anchor) as a 10 mm one will only be around 0.5 T WLL.

For example, an individually tested federal spec green pin shackle to RR-C-271 :

10mm pin WLL=0.75T
11mm pin WLL=1.50T

I have never seen a green or blue pin shackle fail in an anchor cable (no doubt they have) which may indicate that loads on cables are much lower than commonly thought or that the shackles are rated much more conservatively than the chain.

As I say, I would not use a C link myself, but they may not be as bad as some claim if your quoted WL is correct.

John
 

Ships_Cat

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I am not going to get into what would turn out to be an endless argument with you over this but, despite your being so adamant about your claimed disadvantages of chain, forumites should be aware that almost all (perhaps all, I cannot think of a contrary example) professional mooring/anchoring system design is based on a chain catenary to resist the anchoring forces and maintain the anchor stock angle.

It is correct that once sufficient chain is deployed to maintain the catenary under the designed anchoring forces then in some special cases a synthetic rope may be used for the rest of the cable (eg on scientific buoys anchored in very deep water where if all chain was used the weight of the chain would sink the buoy).

It is incorrect of you to claim that a nylon rode or snubber is necessary to avoid shock loads in the cable. We have never experienced any need for such even when anchored in storm force winds or very heavy gusts causing rapid riding back and forwards against the anchor. Also, all (and I emphasise all) larger vessels get by without nylon rodes and snubbers (I am talking about anchoring systems for mobile vessels, not some permanent specialised applications eg FPSO's).

John
 

Swagman

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Maybe a Valuable Project for a Magazine Test?

Suggest if IPC are wondering what may be valuable to readers - how about setting up some breaking tests with shackles, chain, C links, rode - all relativly sized to one another?
It would be good to see what broke first under both increasing and snatch loads - and what those loads might be.

It would presumable also clarify this issue - for clearly there are contrary and firmly held views which as we have seen - confuse those asking for help.

Cheers
JOHN
 

hylass

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[ QUOTE ]

It is incorrect of you to claim that a nylon rode or snubber is necessary to avoid shock loads in the cable.


[/ QUOTE ]

Hi John..

Please have a look at : http://alain.fraysse.free.fr/sail/rode/rode.htm

"We will focus on the rode behavior, with special emphasis on a generally underestimated problem: the dynamic behavior of various types of rode under wind gusts."

"So, an all-chain rode is both dangerous for the anchoring tackle and prone to dragging. On the other hand, an all-nylon rode is safe, but it needs very high scopes that can be incompatible with tight anchorages. Anyway, even with a chain rode, strong gusts always require a very high scope to maintain the anchor (almost) flat on the bottom."

"The high weight of an all-chain rode does not prevent from severe overtensions under gusts, because (1) the chain lacks elasticity, (2) the weight of its upper part is useless. "

"In every case, there must be at least 10 m of nylon in the active rode - more precisely, between the bollard and the chain section (fig. 2.2.6). If you're rich ;-) or you don't want the hook in the water, you can shorten the auxiliary rope, under the condition it is fitted with a spring or rubber snubber like those used on dock lines (fig. 2.2.7). When choosing such a device, however, check that its elasticity range matches the tension range it will have to cope with!"

and, please, tell me what is wrong (or incorrect?) with this theory??
 

Ships_Cat

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As I said in my post - I am not going to get into what would turn out to be an endless argument with you over this but, despite your being so adamant about your claimed disadvantages of chain, forumites should be aware that almost all (perhaps all, I cannot think of a contrary example) professional mooring/anchoring system design is based on a chain catenary to resist the anchoring forces and maintain the anchor stock angle.

You can use whatever you like as far as I am concerned as it is of no business of mine. I only wish to point out the above to others so that they can take it into account in their own decision making.

John
 

hylass

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Hi John,

This is the opposite for me.. anchoring is mine business...:0)

But, as far as "C" links are concerned.. I have nothing to sale!!!.. and, like you, "I only wish to point out the above to others so that they can take it into account in their own decision making."

Anchoring is also a question of security. and taking the risk of loosing your boat (not talking about the crew..) by using "C" links to spare few meters of chaîne.. is just criminal..

My book "Expert anchoring", where I also explain all the new theories about anchoring, will be printed soon in English in the USA , with the preface from a world wide well known circumnavigator, is explaining why most of the traditionnal beliefs are wrong and even dangerous..

I will be very pleased to offer you a dedicated exemplar.. :0)..
 

Ships_Cat

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It would be interesting to see the results of some actual tests of chain anchor cables made up of typical components that people use (eg, the chain, shackles, swivels that might be used) for each size of chain 8mm, 10mm, 12mm, etc). Would assume such tests should be limited to quality components as, especially for swivels (which again I would not use), there are some very poor quality components around.

While quoted breaking loads are available for the various components they are usually quoted as minimums and also one is never sure if there is any conservatism built into the figure.

On new small commercial vessels I usually like to get the yard to use ss shackles which although usually not rated with any greater WLL than a galvanised commercial shackle, normally have a thicker bow material diameter than the galvanised ones (ss ones normally the bow is the same dia as the pin, whereas galvanised the bow material is usually of lesser dia than the pin). At worst, they "look" stronger /forums/images/graemlins/smile.gif.

On our own boat we use commercial ss shackles for chain to anchor (ss bow shackles in our case) and on one occasion I actually bought individually tested green pin shackles to replace them with. Decided to stick with the ss ones when I put the green pin ones beside the ss ones - the green pins one looked very flimsy in comparison (although possibly no stronger, but who knows?)

John
 
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