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

[Captain Crisp]

Morning. My anchor chain has several rusty looking sections, but wherever I have cut into it, it is gleaming steel below the rusty surface.
How do I know when it's past it?
Thanks,
Crisp.

 

[Charlie Boy]

What size boat has it got to hold? My views always tend towards the safe; if in any doubt, replace it. It’ll be a lot cheaper than a salvage or a new boat.

 

[Neeves]

When the diameter of the cleaned wire, from which the chain is made, has reduced by 10% (due to corrosion or abrasion) then the chain would conventionally be condemned. If the picture you provide is anything to go by - its corroded too much.

To check - tie the chain to the back of your car and drag it across a beach, or a quiet road. This will remove the rust, or some of it. Your problem might be that some of the chain is acceptable and some too far gone.

Commonly people would regalvanise but your chain may have corroded too much and increasingly it is difficult to find galvanisers willing to regalvanise chain. Your best option, or a first option, would be to speak to Highland Galvanisers, who have 2 operations - one in Falkirk and one in (I think) Inverness. Ask to speak to Geoff, he is the MD (he is a yacht owner of some repute and a member of YBW). The next issue is getting the chain to a galvaniser - its expensive stuff to move (unless you find a galvaniser local to you).

It might be cheaper to buy new.

Jonathan

 

[Boater Sam]

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!

 

[LittleSister]

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!

We don't know where the OP sails, whether the chain is way oversized or marginal for his boat, or whether he would ever be anchoring in a gale (it could be used only in a sheltered river for all we know).

Stainless steel would be an uncommon choice for those without bottomless pockets.

I would point out that second hand, perfectly serviceable chain can sometimes be found for sale (e.g. on the For Sale section of this forum). Otherwise new galvanised chain can be obtained more cheaply than from the big chandlers if you search around for mooring etc. suppliers.

 

[Norman_E]

Is the entire chain corroded? or is it just that end? If you have sufficient good chain from the other end you might consider cutting off the bad end and either using a shorter chain, or splicing on a rope. If its all like that I agree that it looks too far gone. My kedge anchor has about 10 or so metres of old 10mm chain with about 40 mtres of rope spliced on, so even a moderate length of decent chain can be used to make a useful kedge rode.

 

[CAPTAIN FANTASTIC]

If the rest of the chain is in the same condition as in the picture, i suggest that it needs replacement. However, how often do you anchor, what size boat is it holding and in what conditions. If you use the chain to anchor for a few hours while fishing or lunch, in good conditions, it may be ok for few more years but if you rely on this chain to hold a yacht under any conditions then need to be replaced. Stainless Steel chain is very expensive and it is only good if it is used very regularly.

 

[Captain Crisp]

There's about 20 metres that isn't rusty, so I was planning to splice it to a further 40 metres of octoplait.

I'm not planning anything too wild this year, and it'll be lying in nice cosy East Coast mud.

The good section ooks like this, not rusty, but definitely showing signs of wear...

 

[lynallbel]

We have a saying at work (non boaty) if in doubt there is no doubt.

 

[thinwater]

We have a saying at work (non boaty) if in doubt there is no doubt.

The problem with sort of statement, in the absence of inspection standards and an engineering understanding, is that it is meaningless. The person may be in no position whatsoever to evaluate the risk. Some people are afraid of the dark, small places, or speaking in public.

• What was the specified corrosion allowance?
• What was the specified safety factor?
• What was the manufacturing QC?
• What do we know about failure experience and failure modes?

My consulting business involves inspecting refinery equipment, and on a daily basis I see equipment in critical condition that by appearances was thought to be fine, and tanks that folks were sure were failure risks, testing well within standards with only superficial corrosion. Looking bad and being bad are two different things.

Regarding chain, wear is well understood. It is generally uniform and there are standards.

Corrosion, on the other hand, is inconsistent. It depends on the materials and conditions. Uniform corrosion generally does not cause much weakening until it looks horrendous, but all it takes is one deeply pitted area and you've got a weak link. Pitting, therefore, is what you watch out for. Stainless chain plates are a good example of pitting failure.

In that vein, the first chain has general corrosion that ihas not reduced strength much, but it may/probably has a pitted spot somewhere and is thus at risk. The second has some wear and the galvinizing is going, but there does not appear to be any pitting, so it's good for now. But the best thing to do would be to do what all wise rock climbers do with their rope once and a while; go down the chain, foot by foot, and give it a really close look (in this case for pitting).

 

[Captain Crisp]

That's very helpful!
Many thanks,
Crisp

 

[savageseadog]

There's about 20 metres that isn't rusty, so I was planning to splice it to a further 40 metres of octoplait.

I'm not planning anything too wild this year, and it'll be lying in nice cosy East Coast mud.

The good section ooks like this, not rusty, but definitely showing signs of wear...


View attachment 106124

It'll last a lifetime

 

[Captain Crisp]

It'll last a lifetime

You mean I'll die with it?

 

[Halo]

When will the strength of your chain ever be an issue?
Are you likely to be at anchor in an onshore Gale ?
There are a 100 things that will catch you out before so ignore the chain and plan your passage, sort your pilotage and get sailing!

 

[Neeves]

The main I issue that I identify is that you show 2 photographs one appears to have good galvanising and there is no sign of rust or wear the other photograph shows appalling corrosion. We don't know how much of good chain you have, how much bad chain and the location of the good and bad parts.

10% loss of diameter is the standard measure for determining retirements but as thin water says, or implies, but much of the chain may have more than 90% of good steel remaining but you only need a corroded link every 5 metres - and its a right off. One bad link - every 5 meters - it will fail at the bad link.

If you clean the chain up you will better determine quality, those links now less than 90% of diameter remaining.

If you leave the chain as is it will continue to rust. Don't think of painting it - it will look good for a fortnight and continue to rust.

With no disrespect, and as you asked the question I think I'm correct - you don't have the skills to check the chain and unless you have a continuous length as good as the second section (with no rust). I'd condemn it.

I don't think you will find it easy to re-galvanise - unless you happen to live near to a galvaniser who regularly re-coats chain (and preferably marine chain). I think in fact re-galvanising in the UK is a lost cause (for anyone).

You may retrieve a short length (lets not be pedantic about 'short') enough for a mixed rode, so 20m, or enough for spare rode, say 10m or enough to use as short lengths round rocks for use with shore lines.

Most chain today comes from China, historically it has proved to be of high quality - but there are hundreds of Chain makers in China and as with Europe in the past it will be possible to buy chain that does not meet specification. I am sure you can buy cheap chain (and I'd wonder why it is cheap) and I would stick to reputable suppliers - not being UK based I agree 'reputable' is a word of little value (subjective, like small or light).

If you are to buy new chain:

If you have a windlass the replacement chain needs to fit the gypsy - which means it needs to be the same size as the existing chain. All metric chain of the same nominal diameter has the same sized link, except 10mm chain, of which there are 2 sizes. If you take the gypsy on the windlass off - the size and specification will be engraved in the gypsy, maybe the edge, maybe inside on the plates that face each other. Your chain looks metric but it might be Imperial - that's a whole new can of worms as there are multiple specifications and it might be difficult (but not impossible) to source. If you retrieve by hand you may be able to go down a size (making it easier on your back). Most chain suppliers have chain size/vessel size spread sheets - check them, say Jimmy Green and Lewmar. Yoru chain maybe over sized as historically there has been a religion built round heavier chain (but let's not go there, yet. . Its worth thinking about as smaller chain will be lighter (obviously), cost less and take up less room.

Again - don't rush off and buy - as you identify and determine your way forward - post what you are to do. There is a wealth of knowledge here (some of which is on display on this thread) - use it. Its expensive if you end up with the wrong chain!

Stay safe, take care

Jonathan

 

[Neeves]

When will the strength of your chain ever be an issue?
Are you likely to be at anchor in an onshore Gale ?
There are a 100 things that will catch you out before so ignore the chain and plan your passage, sort your pilotage and get sailing!

When one link has corrosion sufficiently severe its actual strength is less than WLL.

The chain may not have been particularly good in the first place with some (or maybe only 1) poor welds.

The first photograph shows bad corrosions - which may only be superficial but actually looks deeper and looks to be flaking. Are you seriously willing to guarantee the integrity of the chain based on 2 photographs. The chain may be used to secure the yacht and the OPs grandchildren aged 3 and 5. Are you seriously suggesting its a minor risk.

Jonathan

 

[lynallbel]

The problem with sort of statement, in the absence of inspection standards and an engineering understanding, is that it is meaningless. The person may be in no position whatsoever to evaluate the risk. Some people are afraid of the dark, small places, or speaking in public.

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.

 

[Captain Crisp]

Many thanks for all these thoughtful and detailed responses!
I feel 100x more informed.
Crisp (no grandchildren as yet!)

 

[Chris CJ]

We recently bought new chain from Maine SuperStore , stayed with 8mm but upgraded from code 30 to certified code 40 , this provided an increase of 25% in strength without any weight increase . Worth considering when adding weight to the ends of the boat.

 

[peter gibbs]

Morning. My anchor chain has several rusty looking sections, but wherever I have cut into it, it is gleaming steel below the rusty surface.
How do I know when it's past it?
Thanks,
Crisp. View attachment 106085

Doesn't look definitely dud. After stiff brushup check links and anything approaching half wasted can be discarded by cutting back that section, end to ending it, etc. Regalvanising is probably not worth the effort, new chain is not crushingly expensive.

A lot of chain in service is even more corroded than yours, But peace of mind and the loss adjuster's disapproving stare are not to be waved awzy.

PWG