Chain-link concerns: valid?

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dom

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I currently carry 20m of 10mm G40 chain and 60m of 18mm anchor plait. Obviously 20m of chain is way too short as in tidal waters of say 3m charted depth + a tide rise of 4m + 1m boat height = 8m, which even on a 4x rode = 24m of chain. On a blowy day its a PITA transferring the rode off the rope drum section of the windlass and onto the chain gypsy.

I'm going to swap to 40m of chain; so I either require a full 40m section, or I need to connect an additional 20m section to the existing one. Jimmy Green sells these C-links, which seem to be rated to G30, which is fine.
https://www.jimmygreen.co.uk/item/65027/osculati-chain-connecting-link

I have also taken a look at Vyv Cox's excellent website and he's cautiously positive:
https://coxengineering.sharepoint.com/Pages/Clinks.aspx

I will however probably to go for the option of 40m of new G40 certificated chain, as I don't think I'd sleep at night with a C-Link, even if I spot weld the thing shut. What would others do and am I being an overcautious numpty?
 
Personally I don't like joining chain so went for complete replacement. And when ordering anchor chain I work on the basis of start with a number of metres, add some and then add some more.
Our boat came with a theoretical 50m that was actually 47m. I wanted 70m and ended up with I think a smidgen over 80m.

Was quite often at the end of our 60m on the previous boat.
 
From Jimmy Green's website:

"claim"; "welding (...) would ensure peace of mind"; "checked at regular intervals"

Not words that reassure. :ambivalence:
 
There has been much debate about this and IIRC Vyv summarised that the quality C Links are as good as the chain itself. I was going to extend my G30 10mm chain but in the end have decided to upgrade to G70 and have a much longer length for only a marginal weight increase. I do have a spare Crosby C Link which would suit your chain if you would like to give it a go. Here is a link to the certification for the link for information: https://dl.dropboxusercontent.com/u/64249185/Crosby chain link spec.pdf (The blue cross mark identifies the 10mm link)

I think buying a C link from a bog-standard chandler is a no-no, you need to buy it from a manufacturer who certifies the product. They are not easy to come buy in small quantites so I bought two when someone hereabouts was buying volume direct from the manufacturer.
 
No you are not being overcautious. Go for the complete length +10M.
C link is just creating another possible weak link. Pun intended lol.
 
I'm happy with my Crosby link which looks very similar to the Osculati version.

However I had 50m of fairly unused chain and wanted to increase to 100m so a link was the best solution for me.

Having had to hammer the link like hell for 30 minutes with a massive lump hammer I am very confident that no wind on earth is going to budge that thing!

Richard
 
Robih said:
There has been much debate about this and IIRC Vyv summarised that the quality C Links are as good as the chain itself. ....
Click to expand...

I'd agree with that summary, I have a Crosby C Link extending my chain on that basis

Robih said:
...decided to upgrade to G70 and have a much longer length for only a marginal weight increase....
Click to expand...

Where have you sourced that chain as I'm looking at a similar change. I have thought about buying plain 8mm high grade from Crosby and then getting the chain galvanised myself, partly because the quality of pre-galvanising seems to last less well than regalvanised products.
 
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The Crosby C-links are as strong as the chain. The welding advice on the Jimmy Green site might be applicable to their soft-as-butter mild steel links that could have strength about 40% of the chain but if you did that to a heat-treated one like the Crosby you would soften it back to almost mild steel

Two things you need to watch. Crosby C-links are to a USA standard size and may not fit perfectly. If you squeeze the final chain links slightly in a vice they will fit fine. The links are either electroplated or hot dipped with a very high centrifuge spin speed. Either way there seems to be as little zinc on there that they can get away with, and thus they do rust early. Best to paint them for some additional protection and keep an eye on them.
 
Many thanks for all the comments and advice and especially to Robih's for his kind offer to part with a single Crosby Link as opposed to the bulk loads they sell. Regarding the length I'll take the collective go up to 50m as it would be so annoying to get it wrong a second time, though Richard's heroic 100m affair will have to wait until I buy a cat :D

Vyv's comments re strength are very much noted and it's so reassuring that someone has gone to the trouble to independently test these things. But in the end I think I'll go for an all new G40 chain, as I discovered today that my existing chain has no certification and isn't hallmarked, so goodness knows what it is.

Quick point to RobbieW; with regards to regalvanising a chap I know once mentioned that it was harder with G70 high-tensile (?) chain as the hydrochloric acid bath or something can cause hydrogen embrittlement whatever that is. No idea if this is true or not, but it would be worth investigating before purchase.
 
I would agree with the post from RichardS, the extreme hammering required to peen over the 'nipples' on a Crosby link gives confidence in its strength. I am getting my chain regalvanised this winter and this thread has suddenly made me think about the issue of hydrogen embrittelment. Although the chain is G30, the Crosby link is obviously a hardened grade and maybe susceptible to this. Perhaps I need to replace it with a new one post galvanising.
 
dom said:
...Quick point to RobbieW; with regards to regalvanising a chap I know once mentioned that it was harder with G70 high-tensile (?) chain as the hydrochloric acid bath or something can cause hydrogen embrittlement whatever that is. No idea if this is true or not, but it would be worth investigating before purchase.
Click to expand...

Ta for the pointer will check that out - the only company seemingly left interested in galvanising chain is Wedge so I'll talk to them
 
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dom said:
I will however probably to go for the option of 40m of new G40 certificated chain, as I don't think I'd sleep at night with a C-Link, even if I spot weld the thing shut. What would others do and am I being an overcautious numpty?
Click to expand...

If you are in a situation where the strength of the chain is being tested with an all chain rode, then you wont be able to sleep anyway. The banging and snatching will ensure that. But as a good yottie you will use a nylon rope shock absorber between the chain and the boat which will serve the purpose of avoiding the snatch loads most likely to break the chain. If then you were somehow to get into a situation where a continuous load was threatening the chain then on the majority of modern boats I reckon it wouldnt be the chain that would give but the cleat and the deck.

Are you being overcautious - well if you are the typical cruising sailor pottering around the south coast then you likely are being overcautious. Not that this matters because if you are a witterer like me, that link will prey on your mind whether your worries are realistic or not. What is peace of mind worth?

Put your hand in your pocket. The cost is trivial
 
You can get single Crosby links from lifting gear suppliers and these are duly certified with their safe working load. (Also a good source of proper hot-dip galvanised shackles btw).

Having spent all my working life at the rough end of civil and structural engineering I have to say that I find the idea of grade 70 chain somewhat exotic. To me mild steel has an ultimate tensile strength of about 400 MPa and high tensile steel about 460 MPa. Grade 70 is 700 MPa and with increasing strength comes increasing brittleness. I know it is widely used for lifting gear but that is regularly inspected and specified with large safety factors - I'm not convinced that this is the right material to cope well with rough handling and a lifetime of neglect.

The boat that we bought last summer came with a whole 6m of chain and 45m of rope. The Simpson-Lawrence windlass gypsy says it can handle either rope or chain and on the few occasions that I have used it that has been the case. The splice goes round the gypsy followed by the rope without changing onto the drum. I am going to add another 35m of chain this winter using a Crosby C-link
 
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Dom
If you are adding 40 metres of chain just keep in mind the effect this will have on the boat's trim. You may need to shift things around to avoid going a bit bows down!
Peter
 
You can buy single Crosby 'C' links from Tecni Link (or is it Tecni Lift?) in the UK (along with Crosby G209-A gal bow shackles). Do not buy anything else.

The problem with moving to G70 are how to connect the chain to the anchor, I'm interested in how people have achieved that - both for size and strength. Remember that G70 is a one use only product - when it loses its gal and looks tired, its now scrap steel.

To me, and based on Vyv's work, buying G40 seems a bit of a waste of money given that G30 is not reported to fail and most G30 is almost a G40 quality. I would prioritise galvanising quality - as its not much use having strong and expensive G40 chain if it starts to rust after 2 seasons. Vyv has a simple test for gal quality (which he wants to be included as a new British Standard :). Reports on this forum suggest some G40 will not last long before its gal wears off. There is little point in buying G40 if the shackle you use is not a rated shackle and stronger than the chain (look at the strengths of Crosby G209-A (note the 'A' suffix - do not confuse with G209)). Van Beest Green Pin shackles have, approx, 2/3rd the strength of the G209-A shackles. If you can find Peerlink shackles Grade B they are twice as strong as a Van Beest Green Pin.

Highland Galvanisers, Falkirk, will regal chain and anchors and have just done a batch for customers. I do not know why but regalvanising engenders reports of better quality of gal than did the original.

If your chain already contains a 'C' link and you are worried about Hydrogen Embrittlement when regalvanising - simpy cut the link out and buy a new one (they are hardly expensive).


But any comment on G70 chain connectors gratefully received. :)

Jonathan
 
Neeves said:
But any comment on G70 chain connectors gratefully received. :)
Click to expand...

Jimmy Green sell grade 70 with an oversize link on one end.

image.php
 
DJE said:
You can get single Crosby links from lifting gear suppliers and these are duly certified with their safe working load. (Also a good source of proper hot-dip galvanised shackles btw).

Having spent all my working life at the rough end of civil and structural engineering I have to say that I find the idea of grade 70 chain somewhat exotic. To me mild steel has an ultimate tensile strength of about 400 MPa and high tensile steel about 460 MPa. Grade 70 is 700 MPa and with increasing strength comes increasing brittleness. I know it is widely used for lifting gear but that is regularly inspected and specified with large safety factors - I'm not convinced that this is the right material to cope well with rough handling and a lifetime of neglect.

The boat that we bought last summer came with a whole 6m of chain and 45m of rope. The Simpson-Lawrence windlass gypsy says it can handle either rope or chain and on the few occasions that I have used it that has been the case. The splice goes round the gypsy followed by the rope without changing onto the drum. I am going to add another 35m of chain this winter using a Crosby C-link
Click to expand...

Very interesting and many thanks; the thing about metal is that everytime I get something, I end up taking two steps back! The same friend of mine referred to above (a construction chap, as are most Irish :rolleyes:) told me that G40 was high-test and not high-tensile and that what he means by true high-tensile stuff would as you point out be well over 500MPa. But he agrees that G70 is extremely brittle, which is why they don't lift with it. This is now well above my paygrade here, but apparently they use some alloy chain which is the equivalent of G100, somewhat less brittle, but totally unsuitable for galvanising due to hydrogen embrittlement and unsuitable for an installation exposed to both salt water and the possibility of twists.

He sailed a few races with me this summer and when questioned about G70 chain wryly observed, "Look guys, you've got the dosh; I'm sure Yanmar will sell you an engine with titanium sprockets if you pay for it; doesn't mean your engine will run any better though!"

That said, his view is that without a verifiable test certificate or hallmark (which mine doesn't have) the chain should be condemned.

Edit: you seem to have got one of those fancy gypsies where the rope goes in the middle and the chain is caught in the edges, a much better job IMHO.
 
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Resolution said:
Dom
If you are adding 40 metres of chain just keep in mind the effect this will have on the boat's trim. You may need to shift things around to avoid going a bit bows down!
Peter
Click to expand...

Ahh, spot the ex-racer! No, I'm extending the chain from 20m to 40m (+47Kg by my calcs). Still, if I end up sailing around with my backside in the air I can either (a) sell the new chain in the "For Sale" section on here, or (b) procure a bit of Oyster hardcore, mix it with some Mastercrete platinum-blend cement, lob it in the stern and Bob's your uncle :D
 
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