G70 chain

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Neeves

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Is there any user experience of G70 anchor chain. I'm specifically thinking of chain where the owner has replaced the recommended size (for G30 or G40) with the size smaller for the G70. There are catenary implications, less of it with lighter G70, and connectors, getting shackles that match. The other implications are its lighter and takes up less room.

I appreciate this is a very niche area - but a few members have professed to using, or going to buy, G70 so I wondered what actual user experience there was.

The ultimate question is - having used G70 would you use it again if the opportunity came to change.

Jonathan
 
I haven't done this. The attractions are as said, but another detraction is that the chain would then not fit my windlass, and I'd need to buy another chain hook for my nylon rope spring.
 
I cannot think that the hook is deal determining. The gypsy/wildcat is a real issue - which is why it would be a more attractive option for someone buying a new vessel, or a new windlass. But I suspect in the euphoria of the new yacht, straight from the boat show - chain is well below the horizon for many.

But as a metallurgist - any doubts (when you buy that new yacht at the boat show :) )?



Jonathan
 
Neeves said:
I cannot think that the hook is deal determining. The gypsy/wildcat is a real issue - which is why it would be a more attractive option for someone buying a new vessel, or a new windlass. But I suspect in the euphoria of the new yacht, straight from the boat show - chain is well below the horizon for many.
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How much extra would it cost to save how much weight on, say, 40m of chain?
 
Yes I made this change last year. It is an expensive project but i was determined to have good ground tackle which best suited our intended use and our boat. We had 40m 10mm grade 30 with a further 30m 18mm anchorplait spliced on, total length 70m. The fact is that the rode didn't work for us. The chain to rope splice was always a problem when passing through the gypsy and the deck to locker hole and the reality is that the gypsy didn't really cope with winding in the anchorplait. Add to that the concern of using a rope rode on an abrasive sea bed and we concluded that we would bite the bullet with a new rode.

We went for 80m of 8mm grade 70 chain. We needed a new gypsy. Attached to a Rocna 20kg anchor with a rated and tested D shackle of equivalent to the chain specification.

I can't remember all of the research details now but a key requirement was to have an all-chain 80m rode which was of similar weight to the old 40m of 10mm chain + rope. IIRC the 80m of G70 8mm chain is 17kg heavier than the 40m 10mm chain. But that is from memory, needs checking.

The expected benefits have all been there, we frequently anchor in moderately deep water so deploying 60m is now much easier the previously. I sometimes wonder if I should have gone for 100m of G70 but I didn't want the extra weight, I think 80m is adequate.

One unexpected benefit is that the 8mm chain is much quieter and smoother through the winch, nowhere near as "clunky" as the 10mm seemed to be. The anchor winch also seems to find hauling the anchor easier.

Total anchoring investment is significant - but we sleep well at anchor.
 
I replied this morning on my phone but somehow it has not appeared. Paul Chandler went from 10 mm Grade 30/40 to 8 mm Grade 70 when refitting Lynn Rival. The change was written up in either PBO or Cruising. He may well not be a ybw contributor and has now changed the boat for a catamaran:disgust: They have cruised widely since setting off for their second time and I have yet to read of any poor experience.
 
JumbleDuck said:
How much extra would it cost to save how much weight on, say, 40m of chain?
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If you are downsizing from 12mm or 10mm you save 1kg per metre. Not much if you carry 40m, but it is significant if carry 100m. Its like taking a man permanently off the bow. If you down size from 8mm to 6mm the savings are less. You save a large amount of space (as well as the wight) in your chain locker.

Here it would not cost you any more, smaller G70 is not much different in price to bigger G30 brand name. If you are clever, and negotiate, you actually save.

The 'big' cost is the gypsy, if you are not commissioning a new yacht or new gypsy. A gypse will cost around Stg250.

You do need to use long snubbers as you have compromised on catenary. You do need to think how you will connect chain to anchor and search out decent shackles.
 
Another benefit outlined, possibly, by Robih is that if you are only changing the gypsy then the windlass and wiring was specified for bigger chain and now it has a much easier time, that saving of 1kg/m. If you are buying a new windlass there are savings, because you can use a smaller (cheaper and lighter) windlass, but you can 'spend' some of the savings and have a smaller windlass but use a slightly bigger motor. Most motors are simply bigger rating but they have the same fittings and moving up a size, increasing watts, is quite simple on many windlass.

Another benefit - that no-one ever wants to think about - if you lose the windlass its easier to haul in that lighter chain by hand.

The downsides are you have no catenary, a particular problem in light winds because a snubber does not stop you wandering around an anchorage (you just need a shorter scope (and a good anchor). You need to be very careful about the shackle - there is no point in having strong chain if the shackle is weaker. You do need, long, snubbers and need to used them every time.

An unknown - because the chain is smaller might the gal wear more quickly, or is this compensated because the chain is more frequently off the seabed??
 
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Neeves said:
If you are downsizing from 12mm or 10mm you save 1kg per metre. Not much if you carry 40m, but it is significant if carry 100m. Its like taking a man permanently off the bow. If you down size from 8mm to 6mm the savings are less. You save a large amount of space (as well as the wight) in your chain locker.
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A most fortunate typo!
 
Neeves said:
The downsides are you have no catenary,
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You always have catenary and you never, for any size of chain, have any effective catenary in a blow. See Vyv Cox's stuff on this. So, if you want to save weight, why not a short length of chain to avoid chafe and then a drum of dyneema?
 
Because Dyneema floats and wraps itself round your keel, rudder and prop - and is rather difficult and expensive to cut free. It would also be a nightmare to detach if caught in coral.

In light winds if you have light chain the catenary (and friction on the seabed), that is always there (even at the mythical 70 knots), is less effective than with big chain. Once the winds increase, with lighter chain, you replace that portion of the catenary you have sacrificed with elasticity (snubber).
 
There is another problem with dyneema - it and the chain would make an exceptionally strong rode, with no elasticity. There would still be the need for a snubber. This has all been thought of and discussed (dyneema is not an original idea). Attaching a snubber to dyneema is a significant issue. If this was solved dyneema might be another alternative (as it has been made with lead shot incorporated to add the weight necessary to allow it to sink).

Dyneema, very thin, has been used as a rode to stem an adverse tide, during yacht races. Its ideal in this application, the loads are relatively low, elasticity is not an issue, it can be kept reasonably taut, so the fact it floats is not an issue - it can be hand wound onto a reel. Again its not an original idea - piano wire was used decades ago.
 
Neeves said:
Because Dyneema floats and wraps itself round your keel, rudder and prop - and is rather difficult and expensive to cut free. It would also be a nightmare to detach if caught in coral.
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OK, some other more suitable rope, then. The only merit chain has, above the bottom, is weight.
 
JumbleDuck said:
OK, some other more suitable rope, then. The only merit chain has, above the bottom, is weight.
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Suggest me a rope with strength, abrasion resistance, UV resistance etc and I'll consider.

The whole point is, as you mentioned when you suggested a look at Vyv's website, is that the weight of chain is limited. You can carry 300m of 12mm chain - but it would daft on a 35' Benny.

So use lightweight, strong chain (abrasion resistant) and a snubber (the snubber designed to compensate for the lack of catenary).
 
No direct experience with G70. Thought about it last year when replacing my chain and decided against - mainly because in a series of emails with the one remaining chain regalvanizer in the UK I was advised to treat G70 as 'single use' in the sense that the galvanizing process uses high enough heat to damage the strength property of the chain. I believe this has previously been discussed on here
 
Neeves said:
Suggest me a rope with strength, abrasion resistance, UV resistance etc and I'll consider.
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How much UV resistance do you need under water? I've already said that you would use chain for the first bit to deal with the abrasion problem. Is the issue that rope is cheaper than G70 chain?
 
Robih said:
We have used a Petersen shackle to connect chain and anchor, specification here: https://www.dropbox.com/s/88rm0cxdu...sile Stainless Steel D shackle PH2TB.pdf?dl=0

It has a WLL of 2,000kg whereas the G70 has a WLL of 1,500kg.
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Ah!

I did wonder why you were using a 'D' shackle - because that's all that are available from Petersen. I did look at testing them, but they were so expensive my presbyterian Scots upbringing would not allow me to invest.

I'd recommend you look at any of the suppliers of lifting chain, Gunnebo, Pewag, Van Beest (Excel) and look at their omega or connecting links. You can source a connecting link, quite small and neat, that will fit your chain, have it galvanised and it will fit your chain and a standard shackle. Specifically look at G100 units - they will be stronger, when galvanised, than G70 chain. They are similar to the Maggi links, but significantly smaller.

So you then have chain, omega link and a shackle, Crosby bow gal G209 - A.

I will be testing a new gal batch of 120m chain (8mm x G100) and links (G100, 6mm, 8mm and 10mm) in July, if you send me a PM with your chain size and email address (or physical address) I will send you a matching link, detail on UTS and you can use (or not) as you think fit. I'd also send some background on developments in Oz on HT chain.

Jonathan
 
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