Rusty Chain?

Tim Good

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100m of 10mm chain purchased approx 10 years ago. In turned it around a couple of years ago so that the first 50m and still galvanised. But the last 50m, which was the first 50m is rusty.

Upon inspection it all appears as surface rust but is this likely to be purely cosmetic or something I need to deal with.

We’re due to circumnavigate this year and will go to Patagonia which is rather windy!


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doug748

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I had similar last season and the rust marks on deck will drive you nuts if you continue with it. A good illustration of why we should have turned our chain regularly.

The best thing you can do is get it re-galvanized, someone posted a place in Yorkshire that claims to do it - they will be along in a minute no doubt.
I bought new chain and it is already showing the odd speck of rust so it is well worth getting it galvanized properly even if you have to drive to 'up North. My last hot dip lasted c 12 years, I doubt if this new stuff will last 4.

.
 

Neeves

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I thought Highland Galvanisers, Cumbernauld, would galvanise chain - or they did when Geoff was MD. Though a bit out of the way for most.

The chain will now continue to rust - it will only get worse. However the rust looks only superficial and if you use the rusted portion then usage will clean the chain up, and then it will start rusting again in the chain locker. Ideally use the chain, wash with fresh water and allow the chain to dry (crack open the locker hatch to allow air circulation) and you will reduce the rapidity of corrosion. Rust holds water, its porous, cleaning the rust off, with usage) and having clean steel will reduce the rate of corrosion if you clean and dry the chain (as much as possible) Don't keep textile (rope) in the same locker - it holds water, commonly salt water. If the chain sits on top of salty rope, the chain will rust more quickly. Make sure the locker is clean and drains well.

No water, no rust.

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Supertramp

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The majority of my chain had worn galvanising like yours. But on close examination I found a few links with very flaky surface and some degrading of the steel. The chain is usable but the ultimate strength of the chain must be reduced. I am replacing it because the moment you need confidence in the strength of your chain is the time you least want to have doubts in it.

I understand the arguments that (for me) 10mm chain is overkill on a 10T yacht, but better safe than sorry. Especially in Patagonia!
 

Roberto

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Without any scientific rationale, I take as the final end-of-life signal when the chain begins to jump over the gypsy. Mind you, if one anchors frequently not much time elapses after the first rust signals appear.
As you are leaving, consider also the availability of chain in your visited countries, 100m 10mm is about 250kg pallet not sure an Amazon drone could cope with it.
 

ducked

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No experience yet, but I would think oiling the chain would help a bit, and may do so when I get back to the boat. I considered this before I left for Taiwan but ran out of time.

I will probably use sunflower or linseed oil, since this will eventually set. It could still be a very messy hazard on the foredeck but I probably wont get the boat in the water next season so there'll be some time for it to go off. Motor oil/diesel might also be effective but wont go off so would be messier.

I may grind aluminium into the oil, and wonder if running the chain over some scrap aluminium when recovering it, if it was possible to arrange that, would allow the chain to acquire a useful amount of the stuff.
 

Neeves

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Galvanising is an alloying process, the underlying steel and the zinc combine to form Fe/Zn alloys. These alloys are harder, and thus, more abrasion resistant than the underlying steel - anything you add to extend the life of the chain, excepting galvanising, will not last long. These zinc/iron alloys are metallurgically bonded to the underlying steel. Its a strong bond, the closest analogy I can think of - welding (or powder metallurgy). Oil will easily wash off as the chain is dragged over the seabed, whether its still soft or hardened. Similarly if you add aluminium flake it will soon disappear. The seabed is a tough mistress. If the corrosion is flaking you are starting to remove serious amounts of steel. The OPs chain seems to be in the early stages of corrosion.

If you are not using your yacht then flaking the rode on pallet, washing it with fresh water and leaving it under the hull (if on the hard) will help prolong life (of the chain). Leave it in a dank, salty locker - it will corrode more quickly. So wash out the locker - with fresh water. If you wash your chain with fresh water, dry, store in a sealed oil drum then diesel is a good protective coating (that's how many chains are shipped)

10mm metric chain comes in 2 size specifications ISO and DIN the link sizes are different and you cannot use a DIN spec chain on an ISO gypsy and vice versa. Imperial chain, 3/8th", is NOT 10mm ISO nor DIN link size. For other metric chain, 6mm, 8mm and 12mm the DIN and ISO link sizes are the same - its just 10mm that is different. The specification for the chain is on the gypsy, engraved into the circumference or into the facing plates of the gypsy (wherever they are it is likely you will need to take the gypsy off to find and read them)

You can source 10mm ISO or DIN chain from almost any chandler in the UK, Patagonia is different. If the fishing industry is serviced from American sources then it is likely the chains will be Imperial.

Using oversized chain is not a recipe for success. It ruins sailing performance and there is no evidence at all that it loses its gal and corrodes less quickly than smaller chain. Consider - lighter chain will be more easily lifted off the seabed (and thus not subject to abrasion).

Good anchor chain, or good galvanising, should last about 1,000 - 1,500 nights/days at anchor - for a live aboard 4 years.. When you consider most galvanising is 70 microns thick (but can vary between 50 and 100 microns) - the process is pretty amazing. Anchor in acidic muds (slow moving rivers in Asia where there are high nutrient run offs - fish farms) -the life of the chain will be compromised - the acids will dissolve the galvanising.

Jonathan
 

ducked

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Thanks, some useful info there. I'm slightly surprised people use diesel as a preservative since I would have thought it would would be messy and unpleasant to handle.

I wouldn't really expect any treatment apart from re-galvanising to last on the seabed, but I suspect my chain, like most, has probably rusted mostly in the chain locker. People do paint ("cold galvanise") chain and I suppose that is why
 

Neeves

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Thanks, some useful info there. I'm slightly surprised people use diesel as a preservative since I would have thought it would would be messy and unpleasant to handle.

I wouldn't really expect any treatment apart from re-galvanising to last on the seabed, but I suspect my chain, like most, has probably rusted mostly in the chain locker. People do paint ("cold galvanise") chain and I suppose that is why
Diesel is cheap. Throwing a bucket of diesel over your rode in the locker might work - but is likely to make the yacht uninhabitable and be the major source of sea sickness.

Chain is really difficult to handle how ever it is treated or packed.

Cold galvanising simply will not be a success in the rode - too much abrasion.

As a non profit making process I buy (or the owners buys) high tensile chain, G100, from China which is then galvanised and allows smaller lighter chain to be used for the rode. Part of the purchase specification is 'lightly oiled'. Its then grit blasted, no further treatment conducted, and galvanised. Normally for galvanising the steel is pickled, washed in acid and caustic soda (?) - all nasty stuff. If the chain/steel is not clean the gal will not 'take'. But as long as the chain is new, just made, packed in oil drums, liberally soaked in diesel - it does not rust in transit (sealed drum, no water). Grit blasting seems to be beneficial for gal coating, the surface seems 'better able' to accept the alloying.

The reason not to use acid for high tensile steel including chains is the fear of hydrogen embrittlement (and acid is attributed to cause HE).

I don't use G120 from China - its too new as a source of the product, whilst all the chain with which I'm involved is tested in Oz - Chinese G120 is simply too new and not worth the potential aggro.

Most, or all, lifting chain G100 and G120 (less common now G80, its been superseded.) is sold painted, the colour also helps with brand recognition. The paint is tenacious, I've processed it and removing the paint is a nightmare. The paint seems to last well for lifting, little abrasion. Lifting chains are expensive - they are well looked after.

Jonathan
 
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ducked

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Well if diesel works a bit, sunflower oil might too, is also pretty cheap, and considerably less noxious, as long as it doesn't grow mould, which is a possibility.

Aluminium might help prevent that. It didn't seem to happen on treated iron and steel of my car in Taiwan, (which can be very wet, and is usually humid), but ventilation was probably relatively good

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Refueler

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Does anyone throw old chain into a bonfire any more ?? Used to be an old trick to heat and crack off rust ... after a while - pull chain out ... dunk in water to cool and clean ...

Just asking.
 

Refueler

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I thought bonfire were now restricted/banned

Jonathan

Funny you mention that.

Here in Latvia - they allow fires on just a couple of specific dates each year ... BUT because I live with clear area with no risk of 'forest fire' spreading etc. - the local Council have advised local Fire Service and Police that I can have fires as needed.

I have such as this on birthdays .. Xmas .... Nov 5 etc .... basically I have lots of trees and the trimming / wind blown damage etc is collected up and I have large amounts to dispose of ....

 

Neeves

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Funny you mention that.

Here in Latvia - they allow fires on just a couple of specific dates each year ... BUT because I live with clear area with no risk of 'forest fire' spreading etc. - the local Council have advised local Fire Service and Police that I can have fires as needed.

I have such as this on birthdays .. Xmas .... Nov 5 etc .... basically I have lots of trees and the trimming / wind blown damage etc is collected up and I have large amounts to dispose of ....

Here the council collect vegetation. including bits of trees once every 2 weeks and it all goes for recycling, converted to mulch. But the other reason is not safety, though we do have fire bans, the issue is environmental - no smoke.

I've never tried chain in a. fire - driving along a beach, or even the road, works - as Roger said earlier.

Jonathan
 

Neeves

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Does anyone throw old chain into a bonfire any more ?? Used to be an old trick to heat and crack off rust ... after a while - pull chain out ... dunk in water to cool and clean ...

Just asking.
Conversely if the rust comes off in flakes the chain will have lost sufficient mass to condemn it - but will be more than adequate to secure a doberman :)

Jonathan
 
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