G70 anchor chain


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Simon Currin
Simon Currin
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Does anyone have any experience of using high tensile g70 chain and trading down to a smaller guage? From what I have read on www.morganscloud.com etc. 8mm x g70 is as strong as 10mm x g40 which means that either we could carry more chain or carry less weight. I guess it comes at a cost (don 't know how much) but is there another snag? Obviously we would have to change the gypsy too.

Simon
YACHTMATADOR
YACHTMATADOR
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Interesting concept. Not sure about strength but I 'm sure you have researched that bit. The weight saving might be the bigger issue. The reason your anchor digs in is because of the catenary effect of the chain caused by it 's weight. So if you use a lighter chain you need more scope. Remember the difference if you anchor on warp. You will probably find the extra length you need amounts to the same weight you had on the shorter heavier chain, and you had to change the Gypsy. Also if you go to crowded anchorages you will for ever be telling others that they are too close as you have a longer scope than expected. I 'd stick with the heavyer stuff.
Stu
David Tyler
David Tyler
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I 've heard that the higher tensile, higher carbon chains are more susceptible to corrosion.
I have a 10.5 metre boat, with 75m of 8mm chain, and I have to suffer a lot of tooth-sucking from my cruising friends who also go to wild places, who say it 's too light, I should be using 10mm. I know it 's strong enough. Once, when I got the anchor irretrievable jammed under boulders and had to cut the chain, it didn 't yield until I was halfway through the second half of the link, although it was snubbing heavily at the time. Strength is not the issue. Weight certainly is. The first duty of ground tackle is to be heavy. (Who was it who said "the first duty of wine is to be red"? One of the French philosophers, I think).
Simon Currin
Simon Currin
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Thanks for your feedback. I have been digging a bit deeper and found a good review on the Rocna knowledgebase. Their comment on catenary is as follows, "Except in very deep water, chain and its catenary has very little effect on the ultimate performance of an adequately sized modern anchor. The chain 's effect on lowered pull angle and its shock absorption characteristics disappear in the rough weather when they are most required, and the anchor is best helped in other ways. More on this topic is found in the Rode optimizations and Scope vs catenary articles."

"It is not necessary to carry heavy chain merely for the sake of it. Rather, chain can and should be as light as possible, subject to strength requirements. Many boats could lose a large amount of weight by swapping to a lighter but stronger chain, and then investing part of that weight back into a larger anchor. Performance (holding power) of the system is thus substantially improved, while total weight is actually lowered. Find more, including recommendations for chain sizes, in the chain section".

Of course how much lf this is science and how much is gut feel is open to conjecture. i will keep researching for now.

The Rocna link is http://www.rocna.com/kb/Chain
And http://www.rocna.com/kb/Scope_vs_catenary
David Tyler
David Tyler
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"It is not necessary to carry heavy chain merely for the sake of it. Rather, chain can and should be as light as possible, subject to strength requirements. Many boats could lose a large amount of weight by swapping to a lighter but stronger chain, and then investing part of that weight back into a larger anchor. "

I do actually agree with this. That 's why I have a 20kg Rocna, instead of the 15kg that they and other anchor manufacturers would recommend, and only 8mm chain, instead of the 10mm chain that my friends would recommend. But I do think that I 'm right at the top end of the size range, for the practical use of 8m chain.

Catenary might have little effect on the ultimate performance of an adequately sized modern anchor (I read that as meaning "Rocna or Manson Supreme"), but it certainly has a marked effect on the overall, day-to-day performance of any anchor. It remains true that "the chain anchors the boat, and the anchor anchors the end of the chain". A boat that roams around the anchorage, with too light a chain, or chain and warp, is not only a nuisance to others, but uncomfortable for the crew.
cverlaque
cverlaque
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Is there another snag? Yes, if the new chain, while having the same breaking point weighs less. The weight of the chain contribute to the holding power of your ground tackle and you may have to put more chain out to have the same holding power as with the heavier chain. The catanary effect of the chain was reduced. We experienced that in the Med when we traded our 3/8 chain for 5/16 high tensil. We came back to 3/8 and would habe bigger if I could manage it! Christian
Daria Blackwell
Daria Blackwell
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Christian, what type of anchor did you use with the lighter chain?

Vice Commodore, OCC 
cverlaque
cverlaque
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We used both a 45 lb CQR and a 33 lb Bruce with a catanary of 15 lb about (2 lead ingots tied together and hooked to a ring sliding along the chain. Very good holding with that system but you have to retrieve the ingots before bringing up the anchor. Spent 3 years in the Med with that system. We know have a 55 lb Rocna which we like very much. Christian
Simon Currin
Simon Currin
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I think I am now clear that the chain weight will not reduce the absolute holding power of our over sized Manson Supreme though it may increase the amount of roaming around the anchorage. My next dilemma is how to find a shackle for an 8mm chain that matches that matches the strength of either high tensile 8mm or ordinary 10mm. It seems to me that this is going to be the weakest link by a significant margin.
Simon
David Tyler
David Tyler
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You 'll need to use a 17-4PH high tensile stainless steel shackle. Here 's one source:
http://www.s3i.co.uk/lifting-shackle.php#axzz2HFLV6PCd
And I think Wichard make them, too.
GO

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