"C" links for connecting anchor chains!

[hylas]

\"C\" links for connecting anchor chains!

We have been discussing this subject on a previous thread...

I just receive today the latest issue of PLASTIMO catalogue and page 211 (spanish edition) you can read the CMU (maximal Utile charge) for te "C" links:

Diameter 8 mm - Ref: 13250 - CMU 150 kg
10 mm 13251 200 kg
12 mm 13252 700 kg
14 mm 13253 1100 kg

Although you can use a 12 mm "C" link on a 10 mm chain, its strenght will only be 700 kg compared to 5 000 kg for the chain...

my conclusion: DO NOT use them for connecting two anchoring chains...

Alain

 

[andyball]

Re: \"C\" links for connecting anchor chains!

Are these the proper c-links in two parts, that you peen the "rivets" on after assembly? West marine (& others) quote the safe working load for these to be the same as similar iszed proof-coil chain...ie 1200KG working load,4818kg breaking strain for 3/8 chain.

 

[pvb]

Apples and oranges...

Think you're getting a bit confused here, and you're certainly trying to compare apples with oranges by comparing the working load of a connecting link with the breaking strength of the chain!

Like chain itself, connecting links have different mechanical properties according to what material they're made from. So, just because they look the same doesn't mean they behave in the same way.

As Andy points out, West Marine (as well as many other US suppliers) rate their connecting links to be about the same strength as the chain. This also applies to stainless steel connecting links. Bearing in mind the litigious nature of the market over there, and therefore the caution they have to exercise in their marketing claims, I'd be happy to regard the figures they quote as fairly reliable.

It's possible that the Plastimo products are inferior in manufacture to other connecting links. Incidentally, you should note that Plastimo quote SWL (safe working load) at 50% of the breaking strength, whereas the Americans tend to quote a WLL (working load limit) at only 25% of the breaking strength.

 

[ccscott49]

Re: \"C\" links for connecting anchor chains!

There are at least three types that I know of, one would not go round a gypsy, so we can discount that one, although it is a strong as the chain, the other two, both have rivets, but one is a far superior bit of kit to the plastimo one, which is basically junk for what we require. The one I know for stregth, is a forged machined hi-tensile item, with the full chain thickness in the middle of the identical halfs and seperate rivets of a mild steel (which impart no strength to the link), This link is as strong as the chain. I have checked with the suppliers of our (offshore) lifting gear and they are sending me the specs, I will then post them, the links are available down to 10mm only, so below that, sorry!

 

[hylas]

Re: Apples and Apples from the same apple-tree...

Hi PVB,

Yes, you're perfectly right, my previous message was not precise enough..
On the same page, PLASTIMO give the characteristics of the calibrated chain.. So let's compare Apples and Apples.. from the same Appletree..

- According to the PLASTIMO catalog:
A 8 mm chain has a CMU of 1600 kg when a 8 mm "C" link has a CMU of only 150 kg
A 10 mm chain has a CMU of 2500 kg when a 10 mm "C" link has a CMU of only 200 kg
A 12 mm chain has a CMU of 3550 kg when a 12 mm "C" link has a CMU of only 700 kg

I agree with you too.. West marine pretend that their connecting links feature about the same strength as the chain.. but this is (up to my opinion) hard to believe.. They also say that their rope to rope splice after a very sharp"U" turn into the last link of the chain retains about 95% of the strength of the unspliced line. By comparison the " U.S. Rigging Guru" Brion TOSS, (www.briontoss.com) pretend: " The "Traditional Irony Splice", wherein only two strands go through the last link, is the only chain splice that has tested to anywhere near 100% of rope strength".... when, from our own tests, the remaining strength is just slighly above 50% !!!... (and, as we are not manufacturing nor sellling any component related to the anchoring line, you can consider our results as "independant" results).

I perfectly know also that they are different types of steel, with different resistance.. but to reach the same CMU of (for example) a 10 mm chain, the "C" steel would have to be 12.5 time more resistant!!!.. What a challenge!!!...

I've been looking at these "C" links in various Shipchandler shops.. NOWHERE I couldn't find any indication of maximum load.. and I know quite a lot of boats equiped with such "unknown load" links..
I will be very pleased to have an independant organisation testing these assumptions.. Why not PBO???.. I also ask Doug Logan from Pratical Sailor, in relation with Chuck Hawley (WM), if they will be interested to perform these tests..
Therefor, unless you have a precise written indication of the CMU from the manufacturer, NEVER use those "C" links, to connect two lenghts of anchoring chain.. (is it more "politically" correct??)

Happy anchoring during the whole comming New Year..

Alain

 

[vyv_cox]

Testing Apples

Following the discussion on this subject before Xmas, I have made some progress in setting up a test programme for various links, swivels etc. Paul Gelder has told me that YM is very interested in an article on this topic. Testing will be carried out by a UK university mechanical engineering department, test programme and reporting will be agreed beforehand with YM, myself and another contributor to these forums. Intention is that Mark Kopman will write the article.

Further progress in setting up is anticipated after the boat show.

Vyv Cox

 

[hylas]

Re: Testing Apples

WaoooooOOO This is a great new...
If I had the required equipment, I would like to test:

Connecting swivels.. the very simple ones and the beautiful stainless steel ones.. with a straight pull but also side way pulls..
"c" links of course..
Rope to chain splices The "Simpson Lawrence" one but also the elongated one, three strands and Octoplait ones..
If both Mark Kopman and YM will agree, I will be very pleased to write the French translation and to propose it to a French yachting magazine..

 

[wayneA]

Re: Testing Apples

This is great news, look forward to the results. I'll hold off buying that chain for a while.

Cheers

Wayne