Anchor chain link

Neeves said:
These Crosby 'C' links use a 4:1 safety factor which gives a minimum breaking strength of around 2.4t - comfortably more than the MBS of you chain. I assume your chain is 6mm and the 1/4" link will fit.

There are 2 companies called Gunnebo - make sure you are looking at the one focussing on lifting.

Aquaculture & HDG

Now that I think a bit more - if you don't have a windlass you don't need to use a 'C' link - you could use a hammerlock. If you speak to Gunnebo they now make a galvanised G80 chain and they must make fittings for the chain, also galvanised (though I have never seen them in their catalogue). The galvanised G80 is for aquaculture (and frankly I don't see how you can use the chain without fittings). So - if you don't have a windlass (possible if you use 6mm chain) then ask Gunnebo what options they can suggest.

I use hammerlocks, which I have galvanised here, but to join 6mm chain to anchor (and we have a windlass)

Stay safe, take care

Jonathan
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yes I have been browsing their European sites but to no avail - lots of stuff but no C-links
I do have an electric windlass which operates from the helm position so I need a proper c=link type connection or it will jamb and I have 8mm chain.

The one I have ordered with the new extra chain is warranted to 1 ton so if I continue to fail with Gunnebo European I will just go with that ... thank you Jonathan for your help and advice
 
GHA said:
Really wouldn't be that difficult or expensive to do, make a rope tension meter under a length of line taking the load. I've played around with the concept using a bust electronic kitchen scales and arduino. Amazingly accurate so even with the load divided by a big factor it should be enough to show trends anyway even if not accurate down to a kilo. Then just send the data every half second over wifi to a raspberry pi, logging and viewing the data is simple. Certainly would be fascination along with logged windspeed, boat velocity/acceleration etc. One day.. ?
Click to expand...


I have a setup partially made using a load cell to measure the weight of a LPG container that holds 9 Kg of gas. using an Arduino. A new cylinder would be reset to 9kg when a new cylinder if fitted and would count down to zero as the 9 kgs gas is used up.

A friend has a load cell/ display that we use to weigh class sail boat to ensure they are in class rules. I used it to weigh my mono boat for buoyancy checking

a Load cell would be the best with a strain gauge bridge amplifier into an Arduino
 
Sea Devil, how come your supplier said the breaking strain is 2T for 8mm chain? That needs investigation as it should be nearly 4T surely?

In the past some kind forumite organised a group buy of the Crosby widgets. Unfortunately they were imperial sized and didn't quite fit. I have one in my chain. The end chain link needed a fine adjustment with a bloody great big hammer to make the Crosby fit. Also you will need a strong / solid base to bash the Crosby fitting together. A marina pontoon cleat wasn't the idea base. A 4Lb lump hammer just about okay if you used lots of violence.

Hopefully the metric Crosby links fit better.
 
Pete7 said:
Sea Devil, how come your supplier said the breaking strain is 2T for 8mm chain? That needs investigation as it should be nearly 4T surely?

In the past some kind forumite organised a group buy of the Crosby widgets. Unfortunately they were imperial sized and didn't quite fit. I have one in my chain. The end chain link needed a fine adjustment with a bloody great big hammer to make the Crosby fit. Also you will need a strong / solid base to bash the Crosby fitting together. A marina pontoon cleat wasn't the idea base. A 4Lb lump hammer just about okay if you used lots of violence.

Hopefully the metric Crosby links fit better.
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Pete hi,
I just asked my local small chandlers if he stocked 8mm calibrated chain and he said yes - how much do you want - 30m.. I then asked if he had C-links and he only had 10mm - I then discovered he was ordering the chain from his wholesaler = He then volunteered that the C-link had a lower breaking strain than the chain - and he quoted some numbers - My French is OK but if I get into a technical area and some French boat words I get a bit lost.

So I think he quoted the 8mm as 2 tons and the C-link at 1 ton - hence my questions on the forum - to me the 8mm chain is just fine as it is the weight within the catenary that is important - it's in addition to the existing 8mm which is also French in origin I suspect the boat being a Beneteau...

I feel happy that the 8mm is fine - and that the C-link is as well - I have purchased chain in Greece and New Zealand and just added it with a C-link and never given it a thought - I am being over cautious I think.. my Benateau 323 is going to be OK on that chain and link -
 
Neeves said:
Do NOT think that welding the link will make it more secure - you will destroy the temper and its strength. You will need a big hammer and something to act as an anvil to rivet it together.

Jonathan
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I guess there would be no objection to Araldite?
 
Would be interesting to know what the WLL of your average deck fitting is. Which would break first, chain or boat?
 
Neeves said:
You should be able to buy a Crosby 'C' link in the UK from a company called Tecni. They sell mail order (I use them to buy Crosby shackles - I've never bought a 'C' link from them).

I think you are correct - when the tension in the rode is high the last thing you are thinking of is introducing a load cell and recorder into the rode.

I did measure tensions in the rode on our catamaran, 38' x 7t and at 650kg I chickened out and stopped the testing. 650kg loads on the rode are, at best, scary the rode was a 8mm G30. I can assure you that you will have moved long before tensions have reached even 450kg on a 32' yacht. If you have not moved - your rode is the least of your problems - you will be looking at crew mutiny and divorce.

BUT I would still focus on the Crosby link (do not buy anything else, they all 'look' the same - make sure it is a Crosby link - they are the best available, I have not heard of failures (that does NOT mean some have not failed). I would check the 'C' link on a regular basis. Do NOT think that welding the link will make it more secure - you will destroy the temper and its strength. You will need a big hammer and something to act as an anvil to rivet it together.

Jonathan
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Hi Jonathan, watch the clip in #10, and then tell me where you would move to. Sometimes we just have to face the existing conditions.
 
Sea Devil said:
yes I have been browsing their European sites but to no avail - lots of stuff but no C-links
I do have an electric windlass which operates from the helm position so I need a proper c=link type connection or it will jamb and I have 8mm chain.

The one I have ordered with the new extra chain is warranted to 1 ton so if I continue to fail with Gunnebo European I will just go with that ... thank you Jonathan for your help and advice
Click to expand...

There is something wrong with your information.

If you have 8mm chain then the MBS is either 3t or 4t, more likely 3t (but NOT the 2t you quote in your opening post). I think the first thing you need to sort out is what is the strength of your chain and then aim for a joiner that is better, stronger, than the chain. Either that or buy a new length of chain IN ONE PIECE. It is totally contradictory to have a length of chain whose strength is dictated by a joiner that costs a few peanuts - securing a yacht that costs 'lots'. If the chandler told you the strength of your chain is 2t - go to another chandler - he does not know what he is talking g about. If you read other parts of Vyv Cox' website you will find that he tested chains, as have I, and most chain (from any origin) of a G30 strength (MBS 3T for 8mm) is commonly nearer 4t UTS. Forget the idea that the Chinese cannot make anything - most of the chain you will source in the UK is of Chinese origin and they know how to make chain. Whether your chandler tests the chain themselves is unlikely and if they buy from the cheapest source possible the quality might not be so good, there are thousands of Chinese chain makers, but if you buy from a reliable source, Plastimo etc - the quality will be adequate.

The WLL of 8mm G30 chain, which is what most people use, is 750kg and it will have been proof tested to 1,500kg.

Chain will begin to stretch beyond Proof Load and will then not fit the gypsy. Complaints of chain stretching were occasionally posted on forum 15 years ago. I have seen nothing since then. Chain failure commonly the weld was reported at the same sort of time - chain failure has not been a subject of a forum thread for years.

Unless you have some custom made kit on your 32' production yacht then if you were suffering snatch loads of 500kg - you will destroy your bow roller and possibly pull the windlass out of the deck - unless you are using a long snubber (but then the snatch loads will not be 500kg).

'C' links are secured by peening the rivets - there is no need to weld the link nor glue it with araldite. The rivets need to be secured properly and you need a really decent hammer and an anvil. You cannot do this on deck and marinas and boatyards are not going to be keen on you using a pontoon nor cleat. You need a dec ent bit of hardwood and two big hammers, one to use as an anvil (sitting on the hardwood - to protect what is underneath - NOT THE DECK. These rivets are HARD. Now if you use the 'C' link you appear to be suggesting then it will rivet easily as it is mild steel, not hardened - but I'd not trust it to secure a dog, let alone my pride and joy.

There is an alternative and that is do what Roger, did - cut a link and have it professionally welded. The problem is that you rely on the skill of the person doing the welding and the new link will not be galvanised. I would not do it. But then I would not join chain - I'd buy a whole new length. I would NOT use a 'C' link 'warranted' to 1t on 8mm chain. Sorry but its a joke. If its 8mm and warranted to 1t it seems to be based on a low strength steel and it is very possible it will begin to deform at 500kg (and then not fit the gypsy) (this is based on a rule of thumb that yield will be 50% of UTS - and UTS seems to be 1,000kg (note vs 3,000kg for your chain). Now it maybe that the WLL of the 'C' link is 1,000kg - well and good - but the information you are providing is NOT reassuring - as some of it is wrong, like the 2t MBS.

Gunnebo will not list Crosby product on their website - you are contacting them to find out who in Europe stocks product made by their parent company. So ask them for the distributors in Europe, preferably France, for Crosby product.

I'd say Good Luck - but you need more than luck until the information you provide looks sensible - apologies.

Jonathan
 
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GHA said:
Really wouldn't be that difficult or expensive to do, make a rope tension meter under a length of line taking the load. I've played around with the concept using a bust electronic kitchen scales and arduino. Amazingly accurate so even with the load divided by a big factor it should be enough to show trends anyway even if not accurate down to a kilo. Then just send the data every half second over wifi to a raspberry pi, logging and viewing the data is simple. Certainly would be fascination along with logged windspeed, boat velocity/acceleration etc. One day.. ?
Click to expand...

Its all been done - simply use the search engine on Practical Sailor, 'rode loads' should do and the article will be there. I know because I wrote the article.

You will need to extrapolate as it was done on a 38' cat - but no-one would lend me a 30' yacht nor a 50' yacht to do the testing

Here we go:

Anchor Testing and Rode Loads - Practical Sailor

Jonathan
 
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NormanS said:
Hi Jonathan, watch the clip in #10, and then tell me where you would move to. Sometimes we just have to face the existing conditions.
Click to expand...

The vid shows a perfectly example of a yacht yawing, why else does it heel so much. The wind is on the beam and the snatch loads will be large. In those conditions you need to deploy 2 anchors in a 'V' and have decent snubbers, preferably a bridle. A snubber should be at least deck length and it should be thin enough you can see it stretching. In some places, as you repetitively point out, there is no escape - its too far (and you should have listened to forecast daily (that's why they broadcast them daily, or in the case of Oz every 4 hours) to run to anywhere with real shelter. But knowing the conditions that were to develop they should have laid a second anchor, so that the centre of the 'V' was pointing to the primary wind direction - why else do people carry a second anchor and rode? Both rodes should be equiped with decent snubbers, a minimum of boat length. The combination of the 'V' and the snubbers would allow the yacht to sit pointing at the wind, not broad side on. I cannot comment on forecast in other parts of the world but here in Oz you will get 3 days notice of a strong wind event - actually plenty of time to run to shelter and certainly plenty of time to deploy a second anchor.

If you do not carry a second anchor and rode - you should not be there nor should you be in charge of a yacht.

For these reasons we carry an Excel, Spade and 2 x Fortress. (the large Fortress for thin mud (which we have a lot of down Oz east coast (its the location of our oyster farms) the smaller one is big enough to be a primary.

How to: Dealing with Snatch Loads in an Anchorage

Anchor Snubber Tips

Know how: Expanding your Anchoring Repertoire

Know how: Ground Tackle

The art of snubbing, in the nicest possible way - Mysailing

For the OP - your 8mm chain is, if anything oversized for your yacht. At 5:1 scope and 30m deployed all the chain will be off the seabed at around 20 knots, the rode tension will be around 80kgs. At 30 knots your rode will effectively be as straight as a billiard queue - you now need snubbers or request the yacht begin you to move as you need to deploy more chain (or you need to move as if you deploy more chain there are some nasty rocks behind you). Do not rely on catenary - you might not have room.

If the 'C' link does not fit, because it is imperial and not metric - take a drift and enlarge the links at the 2 ends of the chains you need to join. The chains are mild steel and will distort allowing you to use the 'C' link. You will do not harm to chain integrity. Only enlarge the hole as much as necessary - don't get too excited :). When it is all joined neatly paint it with liquid gal (zinc rich paint) and monitor condition.

Jonathan
 
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Sea Devil said:
Pete hi,
I just asked my local small chandlers if he stocked 8mm calibrated chain and he said yes - how much do you want - 30m.. I then asked if he had C-links and he only had 10mm - I then discovered he was ordering the chain from his wholesaler = He then volunteered that the C-link had a lower breaking strain than the chain - and he quoted some numbers - My French is OK but if I get into a technical area and some French boat words I get a bit lost.

So I think he quoted the 8mm as 2 tons and the C-link at 1 ton - hence my questions on the forum - to me the 8mm chain is just fine as it is the weight within the catenary that is important - it's in addition to the existing 8mm which is also French in origin I suspect the boat being a Beneteau...

I feel happy that the 8mm is fine - and that the C-link is as well - I have purchased chain in Greece and New Zealand and just added it with a C-link and never given it a thought - I am being over cautious I think.. my Benateau 323 is going to be OK on that chain and link -
Click to expand...

For something as critical as your rode - get them to write it down.

Jonathan
 
Neeves said:
The vid shows a perfectly example of a yacht yawing, why else does it heel so much. The wind is on the beam and the snatch loads will be large. In those conditions you need to deploy 2 anchors in a 'V' and have decent snubbers, preferably a bridle. A snubber should be at least deck length and it should be thin enough you can see it stretching. In some places, as you repetitively point out, there is no escape - its too far (and you should have listened to forecast daily (that's why they broadcast them daily, or in the case of Oz every 4 hours) to run to anywhere with real shelter. But knowing the conditions that were to develop they should have laid a second anchor, so that the centre of the 'V' was pointing to the primary wind direction - why else do people carry a second anchor and rode? Both rodes should be equiped with decent snubbers, a minimum of boat length. The combination of the 'V' and the snubbers would allow the yacht to sit pointing at the wind, not broad side on. I cannot comment on forecast in other parts of the world but here in Oz you will get 3 days notice of a strong wind event - actually plenty of time to run to shelter and certainly plenty of time to deploy a second anchor.

If you do not carry a second anchor and rode - you should not be there nor should you be in charge of a yacht.

For these reasons we carry an Excel, Spade and 2 x Fortress. (the large Fortress for thin mud (which we have a lot of down Oz east coast (its the location of our oyster farms) the smaller one is big enough to be a primary.

How to: Dealing with Snatch Loads in an Anchorage

Anchor Snubber Tips

Know how: Expanding your Anchoring Repertoire

Know how: Ground Tackle

The art of snubbing, in the nicest possible way - Mysailing

For the OP - your 8mm chain is, if anything oversized for your yacht. At 5:1 scope and 30m deployed all the chain will be off the seabed at around 20 knots, the rode tension will be around 80kgs. At 30 knots your rode will effectively be as straight as a billiard queue - you now need snubbers or request the yacht begin you to move as you need to deploy more chain (or you need to move as if you deploy more chain there are some nasty rocks behind you). Do not rely on catenary - you might not have room.

If the 'C' link does not fit, because it is imperial and not metric - take a drift and enlarge the links at the 2 ends of the chains you need to join. The chains are mild steel and will distort allowing you to use the 'C' link. You will do not harm to chain integrity. Only enlarge the hole as much as necessary - don't get too excited :). When it is all joined neatly paint it with liquid gal (zinc rich paint) and monitor condition.

Jonathan
Click to expand...
Jonathan, I suggest that you actually watch the video before commenting. The reason that the yacht(s) is beam on and heeling over, has absolutely nothing to do with yawing. It's aground!
As you very well know, I do use two anchors when the conditions demand it, and do carry an armoury of suitable anchors and rodes. (I've never tried sucking eggs though). ?
 
NormanS said:
Jonathan, I suggest that you actually watch the video before commenting. The reason that the yacht(s) is beam on and heeling over, has absolutely nothing to do with yawing. It's aground!
As you very well know, I do use two anchors when the conditions demand it, and do carry an armoury of suitable anchors and rodes. (I've never tried sucking eggs though). ?
Click to expand...

Well spotted. I stand exposed - life is too short to watch everything.

Apologies.

There was NO suggestion YOU did not carry more than one anchor, there was no suggestion you did not use 2 anchors. There was not an iota of a suggestion you, in any way, did not exhibit good seamanship. The post was made not with you in mind at all, sorry if it was not focussed - but I know too many who rely on one anchor, no snubbers ....

Methinks you are, far, too sensitive.

Sucking eggs was totally unnecessary (and offensive, maybe I, too, am sensitive.)

Jonathan
 
Poignard said:
If you take a link of chain and make 4 saw cuts across it to half the diameter how can it then be as strong as uncut chain of the same dimensions?

Of course it can't be, unless it is made of material with twice the tensile strength of the uncut chain.

The same argument must surely apply to these C-links.

If I am wrong about that, I would like to know why.
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That is the whole point of using a Crosby link. Your chain is made from mild steel but the Crosby C-link is made from a hardened and tempered alloy steel that has twice the strength of the chain material.
 
vyv_cox said:
That is the whole point of using a Crosby link. Your chain is made from mild steel but the Crosby C-link is made from a hardened and tempered alloy steel that has twice the strength of the chain material.
Click to expand...
Yes, that's what I meant when I said "...unless it is made of material with twice the tensile strength of the uncut chain. "
 
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