Neeves
Well-Known Member
I have done some abrasion testing of a variety of zinc coatings on chain.
All I do is hang short lengths of chain, 300mm, from a piece of galvanised reinforcing bar and hang the bar off the transom of our cat. The tides are 2m and I ensure the length is such that the chains being tested are always touching the surface of the seabed. The seabed is silica sand.
After 6 weeks many of the samples have worn the gal right through to the bare steel underneath.
So - 6 weeks continuous abrasion on sand can remove gal.
This is obviously a more severe environment than any anchor chain will suffer. Anyone who uses their chain as a liveaboard - getting years of life is a decent result - but you are not going to get 'decades' - that's a pipedream.
Some coatings are more abrasion resistant than others, whether some of these are by chance or luck - I don't know. Some gal coatings are a bit thin, again whether this is by chance or built in obsolesce, don't know. But given that the gal life dictates chain life it is surprising that chain makers do not include gal thickness as part of their specification they quote to customers.
The gal does offer protection, other than reducing corrosion. It is harder than the underlying steel and weight loss on bare chain is higher than weight loss of gal - I'd check the thickness of the chain (both for the long and the crowns, where one link rubs another) near the anchor end for your stainless, as it is soft, and compare it with the 'bitter' end (windlass end) as the bitter end will have 'seen' less seabed. You want to look at say 10m from the anchor, as the bit of chain at the anchor should not move much (unless you drag your anchor every time you deploy
Jonathan
Edit
My guess is you don't, or did not, use the gal portion that much - but it did sit in the bottom of the locker. If the yacht is based in the Med the locker is warm and damp and the dampness is all seawater. An unloved chain will corrode, check white rust on google, even if you don't use it. Ideally you want to wash the chain down with freshwater, stick the hose in the locker every time you wash the deck (or it rains), and then keep the locker dry - open the locker cover as often as possible. If you lay the yacht up for winter - take the chain out, wash with fresh water and hang up to 'dry', Vyv hangs his off lines attached to his cradle.
And remove mud. Mud often contained anaerobic organisms that 'exude' sulphur compounds that convert to sulphuric acid - which eat gal for breakfast. You can 'smell' the mud. Very common in historic harbours.
Anchor lockers are simply the space that cannot be used for accomodation and almost perfectly designed to ensure chain life is minimised. Tiny drain holes often leaving a festering puddle in the locker base.
close edit
All I do is hang short lengths of chain, 300mm, from a piece of galvanised reinforcing bar and hang the bar off the transom of our cat. The tides are 2m and I ensure the length is such that the chains being tested are always touching the surface of the seabed. The seabed is silica sand.
After 6 weeks many of the samples have worn the gal right through to the bare steel underneath.
So - 6 weeks continuous abrasion on sand can remove gal.
This is obviously a more severe environment than any anchor chain will suffer. Anyone who uses their chain as a liveaboard - getting years of life is a decent result - but you are not going to get 'decades' - that's a pipedream.
Some coatings are more abrasion resistant than others, whether some of these are by chance or luck - I don't know. Some gal coatings are a bit thin, again whether this is by chance or built in obsolesce, don't know. But given that the gal life dictates chain life it is surprising that chain makers do not include gal thickness as part of their specification they quote to customers.
The gal does offer protection, other than reducing corrosion. It is harder than the underlying steel and weight loss on bare chain is higher than weight loss of gal - I'd check the thickness of the chain (both for the long and the crowns, where one link rubs another) near the anchor end for your stainless, as it is soft, and compare it with the 'bitter' end (windlass end) as the bitter end will have 'seen' less seabed. You want to look at say 10m from the anchor, as the bit of chain at the anchor should not move much (unless you drag your anchor every time you deploy
Jonathan
Edit
My guess is you don't, or did not, use the gal portion that much - but it did sit in the bottom of the locker. If the yacht is based in the Med the locker is warm and damp and the dampness is all seawater. An unloved chain will corrode, check white rust on google, even if you don't use it. Ideally you want to wash the chain down with freshwater, stick the hose in the locker every time you wash the deck (or it rains), and then keep the locker dry - open the locker cover as often as possible. If you lay the yacht up for winter - take the chain out, wash with fresh water and hang up to 'dry', Vyv hangs his off lines attached to his cradle.
And remove mud. Mud often contained anaerobic organisms that 'exude' sulphur compounds that convert to sulphuric acid - which eat gal for breakfast. You can 'smell' the mud. Very common in historic harbours.
Anchor lockers are simply the space that cannot be used for accomodation and almost perfectly designed to ensure chain life is minimised. Tiny drain holes often leaving a festering puddle in the locker base.
close edit
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. Titan chain is made in China but is (or has been when I tested it) good quality, well over strength in common with most Chinese chain, but tends to be priced higher than unbranded chain from China. They offer G30 and G40. Lofrens are also marketing chain now, have been for a couple of years now, I think it too comes from China - it might have changed but initially they only sold a G40 quality. If you find a Lofrens distributor they might carry chain (seems logical 
