How to strengthen chain link

[Pete7]

Originally Posted by JOHNMARDALL

True with some split links, but there's also the question of how much load the split link will take when the boat is at anchor in extreme conditions.
John M

John, does this article help?

C-links – Cox Engineering

[Montanan]

There be many types of couplers and they come with various grades.

The double clevis design depicted in the image of the previous post is quite good. Not sure how well the windlass would handle such under load. Some windlasses are just not forgiving.

This single clevis type in the attached image has the following ratings.

Coupling Link, 9/32 in., 4,300 lb, Grade 100

Coupling Link, 3/8 in., 8,800 lb., Grade 100

Coupling Link, 3/4 in, 35,300 lb, Grade 100

There being strength through design architecture and strength derived from material choices. The single clevis can have a higher rating when made to grade 100 versus say a grade 70 version of the single clevis style, e.g. Double Clevis Link, 3/8 In, 6600 lb, GR 70

One just needs to assess and compare pears to pears and not apples to cumquats. I have no idea if the double or the single clevis design has an advantage.

The starting point would be to determine the rating of the chains being coupled and the connection to the anchor, and then try to approach or exceed such.

There always will be a weakest component. Most of the time that is the anchors hold to the ocean bottom. And with many vessels the weak spot is the hardpoint attachment on deck which is very difficult to assess its true ratings.

The preferable configuration is to use an unbroken length of chain of high test, but if one starts with a length and feels compelled to go longer a coupler is certainly viable, just chose wisely and don't buy inferior quality, which can be a penny wise, dollar dumb situation.

A reference, sure there are many more sources and types. https://www.grainger.com/category/ma...nnecting-links

All the best.

[chrisr]

Originally Posted by Pete7

John, does this article help?

C-links – Cox Engineering

great article - many thanks !

cheers,

[RaymondR]

Take it to a welding shop and get it welded.

[Breaking Waves]

Just a few random thoughts:

1. the connector that Jedi is suggesting is typically called a 'twin clevis link' if you are looking for it. Crosby makes decent ones, as do many of the other reputable commercial rigging suppliers.

2. the twin clevis's are good, but not rated for 'overhead lifting' (eg safety concerned applications) - the option used for that is a 'lok-a-loy' (or hammerlok - same thing) connecting link. Those unfortunately are likely to be more problematic in a windless gypsy.

3. you can pretty easily make a 'dyneema connecting link' - just doing a lashing between the two end links - all you need to be careful of is making its length match the cain link spacing (which is not too hard to do). there is a theoretical concern that it could be cut underwater while being dragged around. Its pretty tough but that is a non-zero possibility. I personally used a steel split connecting link (one of the C link style) and backed it up with a dyneema lashing - worked for years of decent use.

[Mike Banks]

I have used split links like that in logging chains, and never broke one because I never overloaded my chains. But yes, that would probably be the weakest link if it is a cheap knock-off. I would never use one of them on an anchor chain though. There is a better option available

The strongest connection that will go through a hawse pipe and around a windlass is the single link with the top of the link sliced diagonally and separated, leaving sufficient gap to get the chain through. They are not expensive, but they take more care in using them properly.

If you can not buy them, then you can get a small hacksaw and slice a link yourself, then force the split apart by heating the link and using a cold chisel.

I carry these split end links aboard along with some silver and bronze brazing rods and flux, as well as the Yellow bottled propane gas.

The two ends of chain are brought together and the ends of the split link forced together in a vice, or hammered together while I heat it gently using a propane torch. When the links are tightly together, I dip the silver brazing rod in the proper flux and run it between the edges of the join, warming until the entire joint is filled. I then allow it to cool, the vice helps a little.

NOTHING will break that connection, particularly if it is the same pitch but a slightly thicker gauge.

When it is cool, wash it in hot water, brushing it thoroughly to remove all traces of the flux, then paint it, so that the link is easily identified, or you will never find it again.

I use silver brazing because I do not destroy as much of the galvanizing on the link, it having a lower melting temperature than phosphor bronze.

[Jim Cate]

Originally Posted by Mike Banks

I have used split links like that in logging chains, and never broke one because I never overloaded my chains. But yes, that would probably be the weakest link if it is a cheap knock-off. I would never use one of them on an anchor chain though. There is a better option available

The strongest connection that will go through a hawse pipe and around a windlass is the single link with the top of the link sliced diagonally and separated, leaving sufficient gap to get the chain through. They are not expensive, but they take more care in using them properly.

If you can not buy them, then you can get a small hacksaw and slice a link yourself, then force the split apart by heating the link and using a cold chisel.

I carry these split end links aboard along with some silver and bronze brazing rods and flux, as well as the Yellow bottled propane gas.

The two ends of chain are brought together and the ends of the split link forced together in a vice, or hammered together while I heat it gently using a propane torch. When the links are tightly together, I dip the silver brazing rod in the proper flux and run it between the edges of the join, warming until the entire joint is filled. I then allow it to cool, the vice helps a little.

NOTHING will break that connection, particularly if it is the same pitch but a slightly thicker gauge.

When it is cool, wash it in hot water, brushing it thoroughly to remove all traces of the flux, then paint it, so that the link is easily identified, or you will never find it again.

I use silver brazing because I do not destroy as much of the galvanizing on the link, it having a lower melting temperature than phosphor bronze.

Frankly, I have a very hard time believing that such a brazed link could possibly be as strong as a good quality C-type split link... which have tested to be similar in strength to the chain (G-40 or below).

Have you ever tested one to breaking? I guess not, since you state that "NOTHING will break that connection" so a test rig would necessarily fail to break it. I'd love to see proper test results...

Jim

[Muaddib1116]

I assume he's talking about these:

https://www.peerlesschain.com/produc...air-Lap-Links/

If somebody makes high strength versions of these, I could see them being stronger than the c-type split links, and brazing the joint shut could add to that strength. That being said, the lap-links that I linked above don't appear to be rated very strong.

[NPCampbell]

Originally Posted by chrisr

we have a stainless steel joining link in our chain

https://www.whitworths.com.au/chain-rivet-split-link

we were told this is as strong as the chain...but no evidence or actual rating quoted so i'm rather dubious

although it's worked so far in some pretty bad conditions, it was only ever a temporary solution and we're about to replace the full chain length.

cheers,

If your joining link is 316 stainless like the one in the link you provided then it is about 25% weaker in tensile strength than G40 chain of the equivalent size. 316 is marine grade but is not meant to be submerged in salt water. Make sure the shiny surface of the link never looks bubbled as rusting just beneath the surface is common, especially in warm waters.

[RaymondR]

Cross cut the ENDS of the links.

Fit them together.

Fully penetrate weld them with a low hydrogen rod.

Sleep tight.

[sailorphil9]

Originally Posted by Manateeman

Someone ought to start a thread called what free stuff came up with your anchor.

Apologies, I didn't start a thread. but here's my offering (West End, BVI, 6 mths after hurricane Irma). There was also a tree...

[sailorphil9]

Originally Posted by RaymondR

Cross cut the ENDS of the links.

Fit them together.

Fully penetrate weld them with a low hydrogen rod.

Sleep tight.

I'm guessing that's how the original chain is made, but machine welded.


FWIW in reply to another poster, I believe that a stainless steel link could render your insurance invalid if it failed (as indeed would any homebrew). I guess a link cut from the chain and re-welded by a certified marine welder would be acceptable. Guessing!

[Nani Kai]

Originally Posted by Pete7

John, does this article help?

C-links – Cox Engineering

Certainly helped me. Thanks Pete7

[Cheechako]

Originally Posted by sailorphil9

I'm guessing that's how the original chain is made, but machine welded.


FWIW in reply to another poster, I believe that a stainless steel link could render your insurance invalid if it failed (as indeed would any homebrew). I guess a link cut from the chain and re-welded by a certified marine welder would be acceptable. Guessing!

I think the chain is heat treated after it's welded. So the weld is no longer soft?

[Jim Cate]

Originally Posted by sailorphil9

I'm guessing that's how the original chain is made, but machine welded.


FWIW in reply to another poster, I believe that a stainless steel link could render your insurance invalid if it failed (as indeed would any homebrew). I guess a link cut from the chain and re-welded by a certified marine welder would be acceptable. Guessing!

And exactly how would an insurer know that it was a joining link that failed? And for that matter, how would YOU know?

Jim