Grade 70 6mm Anchor Chain

Kwik Decision

Kwik Decision

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As it is looking like we're going to be doing lots of anchoring this year, and we don't run to anything as sophisticated as a windlass, I'm considering replacing our 8 mm bog standard chain with 6 mm grade 70. Does anybody know of a supplier in the UK? Ideally one that can supply a 30 m length with oversized links at each end. I've googled, but only come up with Crosby, but theirs is described as self coloured, and therefore I assume not galvanised, and not suitable for anchoring....

Thank you
 
Andrew

There are only 2 suppliers of gal G70 short link. Maggi and Peerless (ACCO). Maggi's smallest link is an 8mm. Peerless, sold under their ACCO brand, is also 8mm (they have stock in Germany) but in America they make a 1/4" available exclusively through West Marine.

These chains are made specifically for use on a windlass.

However you do not need to match any link sizings dictated by a windlass as you are going to deploy and retrieve by hand and you may find suppliers of a gal 6mm G70 in the commercial fishing industry. I'd have a look at Gunnebo, Rud and Pewag.

The final option is you buy raw G70 and have it galvanised. There have been lots of threads about galvanising chain in the past - so its nothing novel - but you would need to explain to the galvaniser you are discussing G70 (which is a Q&T steel). You will lose strength in the gal process but if you find the right galvaniser (and some do treat HT steels) you will still end up with something much stronger than G30 - it should be what might be called 'G55'. Knox anchor galvanise a 900 MPa steel, in the UK - its not rocket science. One of the forum members is a galvaniser in Falkirk and if you are lucky he might post.

Slightly different, in many respects, but I'm part way toward galvanising 75m of 6mm G80 for the same application - you are not alone (but I'm a bit far away to compare processors!)

Jonathan

edit Sorry, forgot about the larger link. If you look at Jimmy Green's website for Maggi you will find they supply a gal 'C' link. These are common in the lifting industry and if you were to arrange your own galvanising you could throw in some 'C' links, also known as Omega links. Check Van Beests website under their G80 components - they make a 6mm sized piece - but it would need galvanised (and I'd treat some spares as well). You could weld bigger links on but you then need to find someone whom you could trust to do it, not impossible buts its not something all welders are geared up to do. close edit
 
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Thanks to Jonathan for a frank and informative post.

Background reading http://www.morganscloud.com/2011/05/11/things-to-know-about-anchor-chain/
has persuaded me to keep away from anchor chain replacements.

I'd suggest the OP works from basic principles - how much load will his boat exert @ 50 knots and what the anchor working load might be.
I found my boat was quite OK on 6mm G30 (for kedge) and am using 7mm Maggi.
He may find, as I did, that 6mm G30 is adequate for his needs.
 
KellysEye said:
>Grade 70 6mm Anchor Chain

Grade 70 isn't anchor chain it's used by truckers to hold loads down. If you want the best anchor chain buy test chain it has smaller links than ordinary chain. If you want to know more about Grade 70 scroll down here: http://www.1st-chainsupply.com/aboutgrading.htm
Click to expand...

In fact, each grade described in your USA link states it to be used for holding loads down. In European parlance the size of the links is described as either DIN 766 or ISO 4565 and the strength by the grade. Grade 30 is mild steel, Grade 40 has a little more carbon and manganese in its composition and Grade 70 is the same composition as 40 but heat treated. High test chain does not exist in Europe. All the detail is on my website, including USA dimensions which differ from European.
 
Be careful with short link chain. If you want to put a shackle in it only small ones will fit
So if you get it with large rings each end & for some reason the ring wears or you remove it then you will find that shackles will not fit
You can get over this by distorting the link in a vice to make it more round but you do weaken it
 
Daydream believer said:
You can get over this by distorting the link in a vice to make it more round but you do weaken it
Click to expand...

I dispute that deforming the final link weakens it, in fact I think it does the opposite. Work hardening means the cold application of plastic deformation to a suitable metal, a technique used for thousands of artefacts but in yachting terms it is applied to shroud cable and fittings, skin fittings and many others. Deforming the last chain link work hardens it, although I suspect the effect to be minimal. I see no reason why it should weaken it.

Whereas chain is made in a machine with (mostly) strictly controlled conditions and proof tested, an end ring might have been made up by any welder, with unknown skills. There is no doubt that a well-made ring will be strong enough but it does seem a bit of a lottery, especially since it will almost certainly not have been proof tested.
 
Charles, thanks for the kind words!

I would support everything that Vyv suggests (though bow to his vastly superior knowledge on work hardening!).

Imperial Gal G70 has been made by ACCO (part of Peerless) as an anchor chain for years, Maggi have been making a metric gal G70 anchor chain for years. ACCO gal G70 a metric anchor chain was introduced in November last year. I understand as Vyv says that American G70 is made from the same steel as their G43 (which is sometimes called 'High Test' - but this is a meaningless and confusing term) though it might be slightly different with a boron addition. I do not know if this is similar to the practice conducted by Maggi.

Do not be beguiled by American G43, High Test, with its high WLL - G43 is sold with a 3:1 safety factor, G30 and G40 are both sold with a 4:1 safety factor. They are all made the same way, with the same or similar machines, the same skill etc - the safety factors should be the same. Simply look at the MBS - as they are in the ratio of 30:40:43 etc. As Vyv says High Test was traditionally a transport chain - which I think is where the High Test term came from - so I do not understand why you should not use G70, because its a transport chain, but you should use High Test which is a first generation Transport chain.

On shackles - it is quite possible to buy (with a little effort) rated gal 3/8th" shackles (Peerless is but one source) whose pin will fit an 8mm chain. The better of these shackles will have a WLL of 2t and a min break strength of 12t (the slightly lower quality rated 3/8th" shackles have a 1t WLL and MBS of 6t). Some links are a bit small for the pin, hence the need to squeeze the link to fit). But it is also possible to buy 5/16th" shackles in the same range and they have a 1.25t WLL and a MBS of 7.5t or a 1/4" shackle with a .75t WLL and MBS of 4.5t. Unfortunately these shackles all come from America - but if you can get them in Oz you will get them in the UK. The alternative is to look at the 'C' or Omega links (Van Beest).

I would also urge caution, as Vyv suggests, about adding larger links - not an issue if the welder knows what he is doing (but you will need to make that judgement). If I were adding links I would add a few (not just one) as the first link corrodes preferentially and you will want to be able to cut it off - and still use the chain (I know you can reverse the chain but hopefully the gal will last longer than one reversal). For other users - these larger links would never need to go through the gypsy.

Once a G70 chain has been galvanised, hot dip galvanising, it should not be regalvanised.

Europeans are lucky, G30, G40 and G70 chain links are all the same size (except for 10mm) -see Vyv's website! and a gypsy taking, say, 8mm G30 will also accept G40 and G70 (though I would check!). In American each 'quality' BBB, G30, G43 and G70 are all different link proportions (though G43 and G70 are 'similar').

Chain should never be used without a decent snubber (I favour 10m).

Jonathan
 
Thank you for all the responses. I think the conclusion is that I can't buy galvanised grade 70 6 mm chain in this country. I don't have the time, inclination (or i suspect budget) to buy a length and get it galvanised. I'm changing the search to 7 mm grade 40, which has more or less the same strength as the 8 mm grade 30 I have currently, but with a weight saving of around 10 kg on a 30 m length. It is also available from Jimmy Green, for a very reasonable £115.

Cheers
 
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