How do you know when your anchor chain is past it?

[Neeves]

A cautionary comment

I don't know the cost differences in the UK for G30 and G40 chain.

If you were to search historically, and I cannot offer advise on how to do it (but I have been watching out for chain failure reports, there are none), you will find that chain failure (other than poor galvanising) is a bit like looking for hens teeth. It is simply not reported. The last failure I can recall mentioned on YBW was of a chain made in France, a poor weld. Most people use a G30 chain and the migration to G40 chain is simply unnecessary. The galvanising will be as good, or bad, and corrosion rate (once the gal is lost will be similar). Vyv looked at chain about 5-10 years ago, it will be on his website, and most Chinese chain, G30 quality (when he did the survey) was almost to a G40 quality in terms of strength.

Now things may have changed - but based on the data Vyv produced G30 chain is almost as good as G40, G30 chain (which is the most common quality used in Europe (and Australia) if sized correctly is reliable. If the G40 is similarly prices to G30, go for the G40 - but I see no merit in paying 'extra' for a G40 quality - unless it gives you peace of mind (which is of great value).

There was a rumour circulating about 2-3 years ago that because G30 chain was so good then it would be possible for an importer/distributor in Europe to buy G30 from China and sell it as G40........Who would know......? Most Chinese chain was unmarked but American chain has the Grade number stamped into it, as does Titan chain from CMP (made in China) - yes who would know.


G30 x 8mm chain has a Min Break strength of 3,000kg and a WLL of 750kg and should be Proof Tested to 2 x WLL, basically it should not stretch until tensioned beyond 1,500kg. if the tension in your rode, the correct sized rode for the yacht, and assuming the spreadsheets say 8mm - then if the tension ever approaches 750kg - then expect a crew mutiny, if it has not occurred already. A rode tension of 750kg is huge.

If when you look at spreadsheets you find your yacht is borderline 10mm or 8mm - it might then be worth considering G40 in the smaller size (to save weight in the ends, or one end ) but gypsies are size specific and if the yacht has a 10mm gypsy it is an expensive option to down size to 8mm (gypsies are expensive). If you were having a new yacht commissioned downsizing is a sensible option to consider, as the weight of chain will be less (or you can carry more), your electric power requirements will be less. But I might suggest that you look at G70, rather than G40 chain.


In America the situation is slightly different. They have a G30 and a G43. The safety factor for G30 is 4:1 and for G43 is 3:1. You may find that chain in America n is sold on the basis of WLL, that's min break strength divided by 3 or 4. G43 looks much better because its WLL is much higher, but its an arithmetic fudge.

Jonathan

 

[thinwater]

Well we are dealing with the safety of large road vehicles, so any doubts at all means new, safest way everytime.

It is not like a new chain is going to break the bank, new means the man gets to sleep better at night.

Yup, I've run fleets in the past. And there are many, many inspection standards. I'm sure many, probably most things are serviced or replaced based on those standards, not some random notion of risk. Other times, yes, you have to decide. But even the typical mechanic has a long history of observing failure modes. So he is in a position to judge.

 

[Neeves]

Captain Crisp - I'll be interested if you can post your decision, not to be critical but I am interested in how people resolve such issues given the numbers of options that are offered.

I note the grandchildren have not yet materialised. Look forward to the time - you will have short window when you will be treated like god - make the most of it (they soon realise Grandfathers are fallible ).

Joanthan

 

[Captain Crisp]

Captain Crisp - I'll be interested if you can post your decision, not to be critical but I am interested in how people resolve such issues given the numbers of options that are offered.

I note the grandchildren have not yet materialised. Look forward to the time - you will have short window when you will be treated like god - make the most of it (they soon realise Grandfathers are fallible ).

Joanthan

Hi Jonathan,
Current decision is to examine it properly link by link and check for any pitting/excess wear. Hopefully I'll get 20 good metres, to which I'll splice 40 metres of nylon octoplait. I don't have a windlass, so no issues there. Just a stiff back.
Many thanks for spending so much time on it. Your grandchildren are lucky to have such a thoughtful grandparent!
All best,
Crisp

 

[Neeves]

Hi Jonathan,
Current decision is to examine it properly link by link and check for any pitting/excess wear. Hopefully I'll get 20 good metres, to which I'll splice 40 metres of nylon octoplait. I don't have a windlass, so no issues there. Just a stiff back.
Many thanks for spending so much time on it. Your grandchildren are lucky to have such a thoughtful grandparent!
All best,
Crisp

Thanks Captain for the reply and the kind words.

You will be fine with that decision. I don't think you mentioned the size of your chain (and if you did, being a grandfather I've forgotten) but check the diameter of the wire from which each link is made, assume its a G30 quality, look at the strength of a G30 chain of that wire diameter (look at the Jimmy Green website) and then buy octoplait of the correct strength. If the octaplait is very slightly weaker than the chain strength I would not worry and would not buy the next size up of octaplait (I think unnecessary).

You will find, with time, that the chain at the splice will corrode. When it starts to look unsightly simply chop the whole splices off, chain and rope, and make a new one. This will occur over years, not months, but if you intend keeping the boat for years than make the 20 meters, 21 metres ...etc.

When you retrieve with the new mixed rode try to make sure you store the chain and rope separately, Ideally the octaplait coiled hung on a hook so that it can drain and air. The octaplait will store water and if it sits on top of chain it will accelerate the corrosion of the remaining piece of chain. If you wash your decks with fresh water, wash the chain and octapliat at the same time. Both carry salt (and mud, which might smell), which again will accelerate wear. Make sure the chain is not sitting in a puddle of water, cased by the chain locker drain hole being blocked by mud. In the absence of regular washing I also advocate leaving the locker hatch/lid open in rain, more fresh water rinsing, and also leaving the hatch/lid ajar when you leave the boat 'locked up' to allow the hole rode to air.

Dry, clean chain will last longer than wet muddy chain.

There have been a number of threads on joining chain to rope, I think a long splice is one of the favourites - and again I think Jimmy Green has something on their website on how to make one. But use the search engine on YBW.

You are going to have some good lengths of chain left over, maybe. You could join any long piece to the 20m and maybe make 30m with a 'C' link joiner. Vyv Cox has some details on his website. You want the Crosby 'C' link - available from Tecni in the UK. Follow the instructions and hammer the 2 halves of the 'C' link together - do NOT be tempted to weld the 'C' link - you will destroy its strength.

If you have any other lengths of good chain, keep some (you can maybe make a second rode for a second anchor and/or kedge) and they are useful if you tie to rocks or steel encrusted posts (which might damage rope).

A pile of chain, any old chain, can make a good kellet, chum, angel - hung on the rope portion just as a lump of chain (but they are a bit of a faff and you don't want rusty chain on the boat (spoils the deck as I'm sure you already know). I cannot think of any other uses for old chain, big dog? so its the skip or, showing maturity, the rag and bone man.

Jonathan

You'll be good to go!

 

[RivalRedwing]

If you wish to buy new on the East Coast (Southern section) then Eye Marine is well worth a call: EYE Marine - Marine Mooring Specialists

 

[saab96]

Chuck it and buy new stainless steel chain, its not worth risking a boat for. Too late to replace it when the anchor is on the bottom, you are in a gale and holding 2 ends of the chain at the same time!

No, don’t buy stainless. Stainless steel anchor chain is for marina boats that never anchor but want a nice bit of polished steel on their bow roller. S/s is a metal alloy. Even higher grades with well mixed extra chromium, nickel, molybdenum and niobium can still have local concentrations of these elements that allow electrical potential difference within the alloy, so you get a positive charge on one part and a negative charge on another part just like a battery. When electrons flow the s/s can erode rapidly. This happens especially when deprived of oxygen which is why s/s is dangerous below the waterline. When deprived of oxygen it can't re-make the protective skin of chrome oxide. And above the water line this is why you should never tape-over or paint s/s. In a rough anchorage you have to trust every link of your chain. You can't trust stainless chain to not have lost strength.

 

[Dysan]

Is there a rule of thumb on the chain load by size of boat and weather/wave or do the anchor manufactures give a maximum load the anchor will support in ideal circumstuance?

I would suspect the forces involved are nowhere near the breaking strain of the chain, rust or not.

 

[Neeves]

Its complex but this thread, its a fresh thread (but an old article), would be worth following.

Interesting New PS Anchor Test - Cruisers & Sailing Forums

Don't get pedantic about some of the numbers, think in terms of order of magnitude. Hold varies with seabed, some anchors are better in some seabeds than others - I have taken liberties in this post to appease those that criticise the length of my posts.

A 15kg modern anchor will hold about 2,000kg in a good holding seabed. A chain for that anchor might be G30 x 8mm which has a min break strength of 3,000kg, a WLL of 750kg.and should be Proof tested to 1,500kg (at which point it will start to deform permanently). There are spread sheets, very crude equating length of vessel to size of chain.

Crudely the Proof Test of a 8mm chain and hold of a 15kg anchor are similar.

But if you ever were to experience 750kg tension in your rode on an appropriately sized yacht you would be scared witless and wish to be somewhere else, the crew would have mutinied and your wife will be on the phone to a divorce lawyer.

Now you need to read the article and the thread.

Anchors, including modern ones drag at less than their ultimate holding capacity (as Thinwater mentions) and some when they drag will find it difficult to reset. The article simulates a change of tide and wind through 180 degrees - but anchors will drag in a straight line pull.

If we consider old style/design anchors, Delta, CQR and Bruce for a 15kg anchor they have a hold of about 1,000kg - but they have a reported propensity to drag and their dragging is at a much lower tension than their ultimate hold - so there is another mechanism that leads to dragging, other than overloading the anchor.

We don't know what that ultimate mechanism is that causes anchors to drag before their ultimate hold but veering and horsing (and any side effects, twitching) are in the mix. If we knew why anchors dragged, at say, 750kg it might help us design better anchors, or better anchoring techniques but accurate documentation of anchor failure is difficult and thin on the ground.

Currently the only quantitative data we have on anchor performance is hold. We do know that the hold of modern anchors is better than the older designs and that modern designs have less reported incidence of dragging - a conclusion might be that hold is somehow a measure of an ability to resist dragging - so if the hold of an anchor has not been defined, Mantus M1, M2, Vulcan - I personally would not touch them (especially considering when some ARE tested, M1, their hold is questionable). I'd extend the same comment to Epsilon but it has been tested, apparently, by a Classification Society and the test will be against another modern anchor - so I am more relaxed (you make your own decisions).

Reports of G30 chain failing over the last decade and maybe a bit longer - have been absent, completely, so the spreadsheets for chain. size vs yacht size seem right, maybe a bit cautious (nothing wrong with that). The spread sheets may incorporate a factor including the benefit of (what I would say is a bit old school) catenary - so the spread sheets have an element of weight as well as strength. I'm not saying catenary does not exist just that it has led us down a very narrow and restricted path.

I am sure slightly understrength chain would be safe (but I'm not going to define 'under'') but in this case we don't know the strength of every single link which will have been subject to different levels of corrosion depending on where they were stored in the locker and how much abrasion they had suffered in use - so the idea is not sensible. One bad link determines the strength of the whole. Even if you cut 1m out and tested it - you know nothing about the rest. 1 metre is representative of the whole of a new chain - but not of a used chain.

Operator error is obviously a factor, in some anchor failures, bad luck is a factor (catching an old towel in the toe) - so the idea that everyone knows how to anchor and that repetitive articles or threads are BORING - misses the point that if one person learns something new - they are worth it. Not everyone can be as clever as, some of, the members here.

Jonathan

 

[Dysan]

My in-laws come form a farming background and I’m used to lifting stuff and moving things with all manner of equipment Including chains. I’ve also spent about 5 years on HGV moving steel and these are generally secured by chain. Whilst most of these things are certified at a level, the breaking strain is 7 times that!

IMO, you will drag anchor or damage the windlass or front of your boat long before that chain gives up!

 

[Neeves]

I am not aware of any 7:1 safety factors for chain. The only '7' of which I am aware defines strength, not safety factor.

The Working Load Limit of G43 chain in America, which is a Transport Chain, used to secure all sorts of items including, say, bulldozers and logs, is 1/3 of the minimum break strength so a 3:1 safety factor. Confusingly G70, also a transport chain, in America is sold to a 4;1 safety factor, unless it is galvanised in which case it is sold to a 3:1 safety factor. In Europe there are no specific chains used for 'Transport' (though G70 might be used following the nomenclature in America), but all chains are supplied with a 4:1 safety factor, from G30 to G120. The 'G' number is the minimum strength of the wire from which the chain of the wire is made or the minimum strength after the chain is made and subsequently processed (quench and tempered) measured in Mpa. The only exception to safety factors of which I'm aware was Maggi's G70 which was sold with a 5:1 safety factor. There are some other fudges, metric, G120 chain is made with a square wire, so, say, 10mm square rather than diameter, in order to achieve strength (so there is more steel). I stand to be corrected but all chain meets a minimum extension to break of 20%, so the idea that high tensile wire is brittle is incorrect (testing shows that some G30 or G40/43 chain is 'more brittle' (if extension indicates what people mean as brittle) than some G80 and G100 chain (I've never tested G120 chain). Usage of the higher 'G' numbers, specifically G100, is increasingly common as for a given strength the chain is lighter and easier to handle. High tensile chains are increasingly used for anchor chains for oil rigs - for the same reasons, to save weight.

Chain when it is tested to failure should never fail in the weld - the weld should be stronger than the wire.

G30 chain tends to be almost a G40 quality - the strength of most other chains I have tested comfortably exceed the 'G' number (but not spectacularly like G30).

All lifting chain is marked with the 'G' number, the manufacturer and in America the country of origin. The G number is often abbreviated to 7, for 70 and the manufacturer might be a code, C for Campbell (and Peerless uses a range of letters). Some of the best marked chain comes from CMP which (of samples I have seen) it will be marked Titan and CMP with a number. Not every link is marked and you may need to look at 10 links to find a mark, sometimes the mark is poor (or covered in galvanising). Confusingly Titan is also a brand name for a chain distributor in Australia who sell in a variety of countries (for lifting).


You should not damage your windlass - because you will be using some form of chain lock. You may bend your bow roller, or damage the bow of your yacht before the chain fails. You will certainly drag the anchor before the chain fails (unless the chain is understrength) - though if its a good anchor - you may need to cut the chain and abandon the anchor if it is so deep set it cannot be retrieved (it has happened).

Jonathan