Chain life

[MJWB]

The anchor cable on my Westerly Griffon appears (measured by eye against a tape measure) to be 6mm or maybe 7mm dia bar. No idea if 7mm is available as I read of 6 and then 8mm. I've no idea of the age of the chain though it looks in reasonable condition apart from a few links at the inboard end, which always remain in the chain locker. The boat is 89 build so assuming the worst, the chain is original. Additionally, I've no idea how much use it's had apart from my two year ownership. Not many anchorage opportunities my way. Can anyone please advise, how long a life is it reasonable to give an anchor chain?

 

[Tranona]

Pretty much indefinitely unless the galvanising goes and it rusts away. Sounds like yours is not anywhere near that. &mm is made, but is not common. Yours will almost certainly be 6mm which is common and the normal size for your boat.

 

[MJWB]

Pretty much indefinitely unless the galvanising goes and it rusts away. Sounds like yours is not anywhere near that. &mm is made, but is not common. Yours will almost certainly be 6mm which is common and the normal size for your boat.

Many thanks. Reassuring.

 

[Neeves]

I've been following reports of chain life and its a moveable feast. But liveaboards appear to report about 1,200 nights at anchor. I assume that these nights are often consecutive and the number might be nearer 1000 x 24 hour days at anchor. The life is then a function of the wear of the galvanising - and as galvanising is typically 70 microns 1,000 days is quite amazing. Having said this - who sums the number of times they anchor and add to the times at anchor of previous owners?

Wear is not even, the gal wears on the seabed, and not all the chain is on the seabed and even when on the seabed - if there is no or little wind it will not be abraded. Taking care of your chain will extend its life, washing it every time you retreive will extend its life and washing it with fresh water (when you rinse down the deck - stick the hose in the chain locker) will remove salt and salt accelerates corrosion.

Many muds are acid, they smell, and the gal will be corroded due to acid attack - again wash the chain.

Contradictorily try to keep the chain dry, so let the chain drain feely, make sure the drain holes are not blocked in the locker and keep rope (which holds water) away from the chain. Finally the 2 or 3 links at the ends of the chain corrode preferentially - chop them off every time you think they are unsightly. I think this corrosion occurs because there is a rope splice (which is always damp) or because there is an alloy shackle and shank which sets up a corrosion cell.

My guess is that chain well cared for will have the same life span as the yacht - as unless you are a liveabord most people don't anchor much, only in the summer, then for just a night or two - it takes a long time to reach 1,000 x 24 hours.

New yachts at boat shows, keep the drain hole open, don't store chain on top of rope, keep them separate.





But people don't look after their chain - so, as I mentioned, its a moveable feast.

You will find 7mm chain it seems quite common now - but it seems to be a recent innovation - Tranona is correct, as usual, yours is much more likely to be 6mm.

Jonathan

edit

If you have a windlass the gypsy size will be embossed on the gypsy, either on the circumference or on one (or both) of the 2 facing plates. You would need to take the gypsy apart if its on the facing plates - and as your chain sounds, sound, you really don't need to know - unless you want to add more chain.......? to make the rode longer.

 

[William_H]

The galvanising is to stop rust. If rust occurs then you get unsightly rust stains on boat parts and hands. The rust it self mostly protects the under lying metal. However when in under load the rust wears away (as does the galvanising) to allow more rust so the rubbing surfaces of the chain lose metal to the point where chain integrity is in doubt. This is a major concern for mooring chains under load 24/7. This condition is easily inspected for. So provided your chain is not rusted together between links rust is not a reason to replace. If you can tolerate the bad ascetics. ol'will

 

[RJJ]

A set of callipers is a useful tool for very few beer tokens.

My anchor chain has seen quite some use and I check a dozen links or so twice a year. I remember some rule of thumb that said if it still has 90pc of the diameter it's OK. Despite a little rust it doesn't seem to be going anywhere. Remember of course we are measuring the ends of the links where the wear and tear takes place.

As with all things anchoring, it rather depends how you use it. If you have 5000kg breaking strain across the whole system and lose 10pc...., well, it's still not going to trouble you if you mainly anchor in under 20 knots and are willing to divert to sheltered water or a marina if the forecast is grotty. If you are determined to sit out a gale in a remote island then you better be more careful.

 

[Stemar]

The anchor cable on my Westerly Griffon appears (measured by eye against a tape measure) to be 6mm or maybe 7mm dia bar.

Could it be 1/4"? That would be 6.35mm

Aldidl regularly have digital calipers for change from a tenner, I saw them the other day, so they may have them in stock now. I've had one for years and, as far as I can tell, it's accurate to 0.1mm, which is plenty for what I use it for.

 

[NormanS]

The anchor cable on my Westerly Griffon appears (measured by eye against a tape measure) to be 6mm or maybe 7mm dia bar. No idea if 7mm is available as I read of 6 and then 8mm. I've no idea of the age of the chain though it looks in reasonable condition apart from a few links at the inboard end, which always remain in the chain locker. The boat is 89 build so assuming the worst, the chain is original. Additionally, I've no idea how much use it's had apart from my two year ownership. Not many anchorage opportunities my way. Can anyone please advise, how long a life is it reasonable to give an anchor chain?

If the chain is original from 1989, it's very likely to be 1/4". If it's been lightly used and looked after, and looks alright, it'll be fine. If it hadn't been looked after, by this time it would just be a big lump of rust. In summary, your eye is the judge. If there was any significant wear, it would destroy the galvanising, causing rust. No rust - no wear.

 

[MJWB]

Thanks everyone for your informative and helpful replies, all of which have added value to my understanding. Many thanks.

 

[vyv_cox]

Well used for half the year our new chain lasted three seasons. We regalvanised it and it has lasted for twice that but is now getting quite rusty. Unfortunately there are very few options for regalvanising in UK today.

 

[Neeves]

Well used for half the year our new chain lasted three seasons. We regalvanised it and it has lasted for twice that but is now getting quite rusty. Unfortunately there are very few options for regalvanising in UK today.

Maybe Highland Galvanisers in Cumbernauld (and Inverness) - but big problems for most with transport and.....???

Jonathan

 

[NormanS]

There are several galvanising plants in Scotland which will do chain. I've had it done in Glasgow, and Cumbernauld more recently. I've had it done in the past in a couple of other places, but they are now closed.