G70 chain

[Neeves]

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?

I think you are definitely being obtuse.

There are very few ropes with the strength of G70 chain that will also fit a, the same, windlass. Nylon can be sourced as strong as G70 - but it will simply be too big for the windlass - and how are you going to join an overlarge rope to a small link. I think the choice is limited to Dyneema, Kevlar or variants. None of these ropes has any elasticity - so you need a snubber. Please define how you will attach a snubber. All cordage suffers from UV to a greater of lessor extent - chain does not suffer at all - at some stage, 3, 7 or 10 years the cordage will have lost strength, through UV the amount totally unknown - the chain will be as strong as it was - if you think you can warrant the cordage - be my guest.

Cost is not an issue. Dyneema, the most applicable, if you compare strength - is cheaper than steel.

 

[Neeves]

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

I confess to have reiterated this base(less) information, as have others.

However I had a search and there is no data base anywhere that I could find to support the contention (that a second galvanising damaged the specification of gal G70). I decided to investigate. The concept has no technical foundation, regalvanising G70 is technically feasible, there is no loss of strength the concept (re-gal) of G70 has the technical support of one of America's biggest chain makers. The data will be available in the next few weeks.

However - you must be very careful - old chain regalvanised is still old chain. Normal HDG is more abrasion resistant than the underlying steel - so if you leave it too long you no longer have 10mm chain, but now only 9.25mm chain (because it wore) and if it was 10mm G70 it replaced 12mm G30 and loss of chain diameter is more critical.

So the original story was one of those internet myths, of which there are many - repetition making them the more plausible - and apologies for contributing (but I took the trouble to query).

I'm working with G80 chain and the next iteration is G100 (and this might make it possible to replace 12mm G30 with 8mm G100). It is possible to regal the chains I am working with, I have tested - but I would test the base chain, for strength, I would provide to a sympathetic galvaniser 1m to test coat - and then check the chain - if happy I would coat the lot. (and then check again).

In the longer term - regalvanising is going to become increasingly difficult (Valmet in America have stopped galvanising chain completely and the USA chain makers do not offer a re-galvanising service). There are sympathetic galvanisers in the UK and some of them, maybe lots, know the issues of galvanising G70, specifically talk to MM5AHO, see earlier in the thread.

Jonathan

 

[vyv_cox]

OK, some other more suitable rope, then. The only merit chain has, above the bottom, is weight.

Many posters here have described the problems they have experienced using rope or mixed rodes with short lengths of chain. Boats on rope rodes react to every puff of wind, not only making them skitter all over anchorages but resulting in wraps around keels, rudders and propellers. My only experience is the opposite, being on all-chain and having to fend off boats on rope that were determined to collide with us.

Weight may be the only merit that chain has but for me it is by a long way the most important.

 

[[2574]]

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.

Yes, the cost was eye-watering but when I am anchored with 25kts of katabatic breeze pushing me ashore (as I was on Tuesday night!) the cost seems very worthwhile!

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.

Very neat.

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.

Thanks; I'll PM you.

It has also occured to me that changing gypsy from 10mm to 8mm effectively reduces the gearing of the winch/chain (assuming the same number of links in the smaller gypsy) which would account for the easier running windlass. But maybe there is an additional link in the 8mm gypsy; I didn't bother checking.

 

[[2574]]

By the way - if anyone is interested I have our old 10mm chain gypsy available for sale. See pictures here: https://www.dropbox.com/sh/rtjzeuzq6dewxtj/AAAVGHJ0rPvhte2gGvVqM2iia?dl=0

It is from a Lofrans Cayman windlass though I believe that it also fits other models.

Rob

 

[thinwater]

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?

This is an over simplification.

A boat using BBB chain in 10-20 meters of water will have quite a bit of catenary up to 35-40 knots (depending on the particulars). I have tested this (with load cell for articles), it matches with theory, and finally user experience. If the scope is long enough, curve remains until very high wind. But it does take deep water and a lot of chain.

 

[JumbleDuck]

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.

What does the galvanising process do to the heat treatment of a G100 link?

I think you are definitely being obtuse.

Not really. I'm just burying my head in my hands at yet another one of your anchoring threads in which anything expensive is lauded to the skies.

Weight may be the only merit that chain has but for me it is by a long way the most important.

I agree completely. I like having a nice heavy anchor chain for just your reasons, which is why I don't buy the "must get new shiny, costs more, weighs less" argument. If you want light, use rope - I have 100m of octoplait on a reel, just in case. If you want inertia, use nice heavy chain. Lightweight, expensive, unregalvanisable chain is neither fish nor fowl.

 

[Neeves]

What does the galvanising process do to the heat treatment of a G100 link?

Reduces strength by 15%


Not really. I'm just burying my head in my hands at yet another one of your anchoring threads in which anything expensive is lauded to the skies.

My G80 chain cost about 60% of the cost of brand name 8mm G30. My windlass gear box was lubricated with seawater and mud and the motor casing corroded excessively. I needed a new windlass. The new windlass, being smaller was Stg250 less than the 8mm model.

It was a save, save. As usual you imagine too much - get facts and stick to them. Fabricating to suit your argument is not something a senior member of a prestigious University should be proud of.



I agree completely. I like having a nice heavy anchor chain for just your reasons, which is why I don't buy the "must get new shiny, costs more, weighs less" argument. If you want light, use rope - I have 100m of octoplait on a reel, just in case. If you want inertia, use nice heavy chain. Lightweight, expensive, unregalvanisable chain is neither fish nor fowl.

Jonathan

 

[thinwater]

It's amusing how these thread polarize the respondents, as though there could be one right answer.

a. Boats very from the very heavy to sprightly multihulls.
b. The "value" of weight savings varies from very little (some folk don't mind rocking and sailing slow) to considerable. At the extreme ends, I'm guessing the range is $10-100/pound. We wouln't use carbon and carbon fiber if weight made no difference to us at all. This is obvious on the face of it.
c. Boats vary in their tendency to wander. I've watched some real gallopers. I've also had cats that sit still on all-rope (wide bridle).
d. Depth of a typical anchorage matters. I only anchor in more than 7 feet every few years (I only draw 3 feet).
e. Do bottom hazards require all-chain? Some places they do. Some not.

My feeling is that all of the chain grades have their place. It depends on the boat, the anchorage, and the math, which I grant you, is not simple. For me, the right answer is relatively light chain and only 100 feet of it, backed by rope. I like to keep weight out of the bow (fast, light boat) and 100 feet gives me all-chain 99% of the time. If I had monohull in deeper, rocky waters, I might go heavier and more of it, since the weight penalty would be less, the water deep enough for catenary to help, the boat would probably be more nervous. So, more than one right answer.

 

[Neeves]

Our usage of 6mm G80 instead of 8mm G30 underlines that you need good snubbers, or in our case, a bridle. It also underlines you need to be able to have snubbers for everyday usage, say upto 35 knots, but these snubbers will almost definitely be inadequate for stronger winds, so you need 'storm' snubbers and have thought through how you are to attach them.

In light winds and fluky conditions there is less dampening from the chain (friction on the seabed) and lower scopes (and an anchor that will perform at lower scopes) seems to be an answer.

If we had known what we know now - we would have used G100, it costs little more and offers 20% more strength. (so instead of equalling the 8mm G30 we used previously is would offer a further 20% strength with the same extension to break).

Otherwise - our experiences are all good - apart from the whole idea inexplicably provoking some individuals.

I do note the paucity of members claiming to use or have considered G70 - which does seem to be a slight contradiction (or surprise) as Maggi make it and Jimmy Green, appear, to sell it.

Jonathan

 

[Neeves]

Thinwater - I can only agree, different solutions for different yachts. If we sailed a classic heavy displacement yacht chain weight would probably not be a concern. Similarly if we did not make long passages but pottered (not being disrespectful - cannot think of another word) then chain weight would not be an issue. I have no problem with anyone who fits this categorisation - or thinks catenary and chain weight is critical. But we have a lightweight yacht, sail long distances and weight is an issue (common on most multihulls). We have seen the 'recommended' sized chain (apparently) as straight as a billiard cue (its not straight, just looks it) at 30 knots and are sceptical of the value of catenary - as we sometimes have wind well in excess of 30 knots, measured at the masthead (and cannot deploy more chain because there is no room (or we did not have more).

HT chain was the answer - we wondered how other people faired having made the same decision, what there experiences were - was there anything that could be shared.

 

[RupertW]

Thinwater - I can only agree, different solutions for different yachts. If we sailed a classic heavy displacement yacht chain weight would probably not be a concern. Similarly if we did not make long passages but pottered (not being disrespectful - cannot think of another word) then chain weight would not be an issue. I have no problem with anyone who fits this categorisation - or thinks catenary and chain weight is critical. But we have a lightweight yacht, sail long distances and weight is an issue (common on most multihulls). We have seen the 'recommended' sized chain (apparently) as straight as a billiard cue (its not straight, just looks it) at 30 knots and are sceptical of the value of catenary - as we sometimes have wind well in excess of 30 knots, measured at the masthead (and cannot deploy more chain because there is no room (or we did not have more).

HT chain was the answer - we wondered how other people faired having made the same decision, what there experiences were - was there anything that could be shared.

I'm planning at some point to make the change from 10mm (currently have 60m of it plus 60 rope) to 8mm and probably 100m of that. The catenary illusion has been done to death on other threads with the maths showing chain weight really helpful except under load as the main benefit is how much the curve can stretch out to dampen shock loads, and if the curve so nearly straight that only a few cm can straighten further you've lost any benefit.

My two issues are expense (new chain and new gypsy) but mostly that I really want S/S chain as my anchor locker is so poorly designed and unchangeable that chain piles up along a sloping locker bulkhead from when the locker is nearly empty onwards so needs continuous manual interevention with a broomstick. I think slinky S/S would be far better but haven't done the calculations about whether 8mm S/S is still going to leave the chain as the strongest part of the whole system.

 

[Neeves]

I have an 8mm Muir Atlantic gypsy looking for a home, I accept that Oz is a long way from you - but parcel by sea is not that expensive - unless you are an American and think national post is dead and you must use an expensive courier

If you go the stainless route you might be able to do a deal with the chandler - you'll buy stainless if he throws in a free gypsy - don't laugh - its happened here.

If you move down a size, 10mm to 8mm you will use less room, for the same length of chain, in the locker. Go to your chandler and look at the drums of different sized chain and check the length in each - the differences (length vs weight) are remarkable. 8mm chain is easier to shove around, its lighter, in the locker than 10mm (which is almost impossible to push about).

We went from 8mm to 6mm, hence the 8mm gypsy, and from 50m to 75m. The chain locker looks malnourished (sadly we can do nothing else with the space).

I cannot comment on stainless chain - but if you are going from 10mm gal G30/40 to stainless G60 Cromox then I can understand why you mention expense. As mentioned earlier you can source decent G60 'D' shackles (not bow), Petersen and Cromox - but they are not cheap.

If Vyv does not comment, send him a PM - he might offer advise on going the stainless route.

Jonathan

 

[JumbleDuck]

Fabricating to suit your argument is not something a senior member of a prestigious University should be proud of.

My employment and my employers have nothing whatsoever to do with my posting here. I'd be grateful if you could avoid these irrelevancies.

 

[stranded]

We bit the bullet and replaced 10mm bog standard with 100m of 8mm G70 (7100 bl) and ultra flip swivel (found an 8mm gipsy in spares which softened the blow ever so slightly). Damn ultra flip doesn't fit the Bugel anchor! So back to a Kong with a straight bl of 5000kg, lateral 2000kg. The former I can live with, the latter not, so I have a couple of links of 10mm to insert between swivel and anchor to minimise risk of lateral load, but still need to pick up a suitably strong shackle that will reliably pass through the somewhat narrow through-stem roller. Or swap out the anchor. In the meantime, the current set up should be fine for normal conditions convenience, and we plan to put out the big fortress kedge with 10mm chain plus rope rode if we get caught out. Such a can of worms.

 

[JumbleDuck]

Similarly if we did not make long passages but pottered (not being disrespectful - cannot think of another word) then chain weight would not be an issue.

I thought that in general potterers cared more about anchoring because they (we!) do it more often.

 

[Neeves]

My employment and my employers have nothing whatsoever to do with my posting here. .

 

[Neeves]

Nooka,

I've never checked but have wondered - the Ultra, unsurpisingly, is designed round their anchor - I did wonder which anchors it might not fit.

Take 2 good rated gal bow shackles Grade B, cut the handle off the end of the clevis pin (don't know what the name is) - ensure you do not cut off the shoulder - or the clevis pin could pull through the eye. Slot the cut end for a big flat screwdriver. Paint with zinc paint. Secure with Loctite. You need 2 as when the first one start to look grotty - you have spare. A 3/8th" Grade B has a WLL of 2t (I think a 1/2" is 4t). Loaded at 90 degrees these fall by 50%.

Our G80 has a UTS of 3,750kg approx - we are using 3/8th" Grade B shackles and G100 Omega links.

The big issue, as you (and everyone else) have found, with G70 is that no-one has seriously thought about the connectors and chain hook. Why the chain makers don't offer a package - just another of those great marine marketing mysteries - but it might be a part explanation why so many are deterred.

Jonathan

 

[GHA]

I thought that in general potterers cared more about anchoring because they (we!) do it more often.

It's not actually what happens though, cruising you often end up doing both. Long distance between cruising grounds then "pottering " once you get there. I'm in the 4th anchorage since Wednesday. Usually unknown as well so most definitely care about anchoring

 

[JumbleDuck]

It's not actually what happens though, cruising you often end up doing both. Long distance between cruising grounds then "pottering " once you get there. I'm in the 4th anchorage since Wednesday. Usually unknown as well so most definitely care about anchoring

Fair enough. My image of wandering seabirds, touching land only once every few months, was obviously not quite right.