Anchor chain

[WindyWindyWindy]

I've flipped my anchor chain.

The first two feet were quite corroded. I removed the first link and I've painted the corroded ends, but that approach has immediately failed following contact with the windlass.

Given the short length that appears to be affected, is there some kind of protection that people, erm, strap on? To minimise chafe...

 

[thinwater]

I've flipped my anchor chain.

The first two feet were quite corroded. I removed the first link and I've painted the corroded ends, but that approach has immediately failed following contact with the windlass.

Given the short length that appears to be affected, is there some kind of protection that people, erm, strap on? To minimise chafe...

Some reason you didn't cut several feet off both ends? Seems obvious. Always buy chain and rope a little long to allow for trimming over time.

 

[Neeves]

I don't entirely understand you post but simply cut off the corroded portion.

Thinwater beat me to it.

I'm not sure why you are worrying about chafe - is this a mixed rode? Chain does not normally suffer from chafe. It its a mixed rode then simply add a shackle, or a 'C' link (which will be new and thus not corroded) and will not chafe until the shackle ofr 'C' link corrode again.

I'd look at why the ends of your chain are preferentially corroding - though its not unusual as the ends in contact with rope will always be in a contact with a damp rope.

If you were a bit more generous with describing the issue we might be able to help you further.

Jonathan

 

[thinwater]

I could add that it is not unusual for people that splice rope-to-chain to cut off only 1-3 links every 3-4 years because it is the spliced link that corrodes (the rope keeps it wet). That is a special case.

 

[vyv_cox]

Chain connected to a stainless steel shackle or swivel.will lose its galvanising very slowly, In my own case after about five years of anchoring for nearly half the nights of the year. Even then there was very little red rust. Only about four or five links are affected. I cut them off as needed.

 

[WindyWindyWindy]

Well, this chain is also about 5 years in. The galvanizing appears to have gone from the first couple of feet, maybe a bit less. There's still plenty of good metal for the time being, especially as the boat-end rarely gets wet.

I had assumed that this was due to contact with the seabed close to the anchor, but maybe it's electrolytic?

Would an anode help?

 

[Neeves]

Unless your anchor moves around a lot - the section of chain next to the anchor does not move very much, does not suffer (much) from abrasion and the galvanising should last longer than other sections of the rode. The part of the chain that does suffer abrasion is that part on the seabed that is dragged, across the seabed, by the yacht as the yacht moves.

If you have a mixed rode and store the chain on top of the wet rope - then the salt environment will accelerate corrosion.

It is common for the first few inches, or about 2.5 times as long in metric units, to corrode - that portion directly attached to the anchor. The corrosion is well known - the reasons less well known (maybe the close association of a mild steel chain to an alloy shackle and shank). Normally this is easily removed, bolt croppers - who notices the loss of 6" of their rode. Maybe if this trimming has not been done the first couple of feet of rode and now showing the same mechanism.

If its 2 feet - cut them off and forget all about it - until 12 months time and check again.

Jonathan

 

[WindyWindyWindy]

It is common for the first few inches, or about 2.5 times as long in metric units, to corrode - that portion directly attached to the anchor. The corrosion is well known - the reasons less well known (maybe the close association of a mild steel chain to an alloy shackle and shank). Normally this is easily removed, bolt croppers - who notices the loss of 6" of their rode. Maybe if this trimming has not been done the first couple of feet of rode and now showing the same mechanism.

Then an anode on the chain would stop it wouldn't it?

The rode is mixed but the rope rarely gets wet as there's mostly enough chain.

The chain by the anchor is probably the driest bit as it goes in the locker last.

I guess maybe it's cheaper to chuck a link every few months than it is to put an anode on anyway..

 

[vyv_cox]

Then an anode on the chain would stop it wouldn't it?

The rode is mixed but the rope rarely gets wet as there's mostly enough chain.

The chain by the anchor is probably the driest bit as it goes in the locker last.

I guess maybe it's cheaper to chuck a link every few months than it is to put an anode on anyway..

An anode would do very little, mainly because electrical contact between links is very poor. Most corrosion seems to occur when the chain is in air, rather than underwater. Even the most frequent anchorers probably only have their chain immersed for less than 50% of the time

 

[Neeves]

Then an anode on the chain would stop it wouldn't it?

The rode is mixed but the rope rarely gets wet as there's mostly enough chain.

The chain by the anchor is probably the driest bit as it goes in the locker last.

I guess maybe it's cheaper to chuck a link every few months than it is to put an anode on anyway..

Normally with a mixed rode the rope is retrieved first. If the rope is seldom needed (you anchor in locations that do not need your rope) then the rope will sit on the bottom of your locker.

Your chain will be retrieved on top of the rope - and the rope will be continuously soaked from water running of the wet chain.

Your rode, both rope and chain, cannot dry out, its damp from seawater and the locker hatch will be closed - moisture will evaporate, condense on the locker walls, run down the sides of the locker - constantly replenishing the moisture. No wonder you have corrosion.

Store the rope such that the chain does not sit on top of it (you don't use it too often, coil it neatly and hang in the locker. Put a perforated false bottom in the locker (part of a milk crate) or retreive the chain to a milk crate. Now you will have self draining chain (make sure the locker drain orrifice is clear). When you wash the deck, swill out the chain locker, chain and rope, replacing salt and muddy water with fresh water and take advantage of good weather to open the locker lid (or wash the chain with rain).

Now you are giving your chain a chance.

Our rodes were for a cat but to give you some ideas:

We had 2 rodes.

We lined the locker for our primary rode, 75m of 6mm HT chain, with perforated, cheap, rubber door mats which allowed the chain to drain. The locker drained aft to 2 x 25mm drain holes.


Our second rode was mixed rope and chain 40m of 12mm 3 ply nylon rope and 15m of 6mm HT chain. I coiled the rode inside a milk crate and simply dropped the chain into the hole inside the coils of rope. Both the rope and chain could drain and air.



When possible I'd wash, swill down, the locker and milk crate, if raining I'd have the milk crate on deck (not onerous as often we anchored under arduous conditions and I'd have the crate and an anchor available).

Jonathan

 

[Chiara’s slave]

Is there a reason, apart from cost, why the anchor gurus don’t seem to mention stainless chain? Surely it must last longer, offsetting the cost, and it’s much cleaner on board.

 

[WindyWindyWindy]

An anode would do very little, mainly because electrical contact between links is very poor. Most corrosion seems to occur when the chain is in air, rather than underwater. Even the most frequent anchorers probably only have their chain immersed for less than 50% of the time

It's the bit of the chain that is nearest the anchor that corrodes, the stuff that is rarely in the water hasn't corroded at all.
If it's electrolytic then an anode should help, something like chain markers made out of zinc?

Normally with a mixed rode the rope is retrieved first. If the rope is seldom needed (you anchor in locations that do not need your rope) then the rope will sit on the bottom of your locker.

Your chain will be retrieved on top of the rope - and the rope will be continuously soaked from water running of the wet chain.

Your rode, both rope and chain, cannot dry out, its damp from seawater and the locker hatch will be closed - moisture will evaporate, condense on the locker walls, run down the sides of the locker - constantly replenishing the moisture. No wonder you have corrosion.

Well, yes the rope ends up in the bottom, and the chain that is attached to the rope ends up on the rope directly, then the chain in the middle is on that chain and finally the chain attached to the anchor is right at the top, and as such the driest part of the locker (which is admittedly not that dry). Yet it is that part that corrodes.

The locker does have a stand-off above the drain so nothing is actually sitting in water directly, but the rope is damp as you say. Unfortunately you have a much grander looking anchor locker than mine, I'm not sure how much hanging space I can add.

I honestly thought this was normal, all anchor chains seem to corrode in the first couple of feet of the anchor.

 

[Neeves]

Is there a reason, apart from cost, why the anchor gurus don’t seem to mention stainless chain? Surely it must last longer, offsetting the cost, and it’s much cleaner on board.

I don't recall the details

The upfront costs are large.

The chain will effectively last forever (one of your points)

The chain will last much longer than the owner will own the yacht

The owner is unlikely to recover even a fraction of the residual cost when he sells the yacht.

It looks a bit flash - you really need a stainless anchor and though the chain will be duplex you will have great difficulty find a duplex anchor (other than an Ultra, and I don't know that it is duplex).

I preferred the other option, galvanised (longer lasting galvanising, better than HDG but not a match for duplex) HT chain allowing a smaller chain size. To me weight was more important.

Jonathan

 

[dunedin]

The first couple of feet of our anchor chain started to corrode after 5 years or so - but was superficial. It’s the bit that is exposed on deck when anchor on the bow. After 10 years scraping on rocks the Rocna also has a rusty tip. Now simply spray anchor and first metre of chain annually with this galvanising paint - https://www.amazon.co.uk/gp/product/B0BTTDFJ4H/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Works fine. Occasionally lopped one or two links off closest to the anchor. After 7 years end for ended the chain.

 

[Chiara’s slave]

We now have 10 metres of 8mm stainless chain, and about 50 metres of octoplait with a nylon eye spliced in. Hence the question. The anchor is an alloy Spade. Previously we’d had an occasional bother bedding it in, more chain has made that a fading memory.

 

[vyv_cox]

It's the bit of the chain that is nearest the anchor that corrodes, the stuff that is rarely in the water hasn't corroded at all.
If it's electrolytic then an anode should help, something like chain markers made out of zinc?

The part that is always on deck between anchor and windlass?

 

[vyv_cox]

Is there a reason, apart from cost, why the anchor gurus don’t seem to mention stainless chain? Surely it must last longer, offsetting the cost, and it’s much cleaner on board.

The most readily available and less costly stainless steel chain is made from.AISI 316. The best that can be expected from it is Grade 30 but this may well be sufficient for your needs. I agree it offers many benefits at x4 (?) the cost.
Many liveaboards now buy Cromox chain that is grade 50 or 60. There is a 316 version made from hard-drawn wire or a duplex version that is heat treated. Both are even more expensive but justifiable if your whole life is spent aboard

 

[Chiara’s slave]

The most readily available and less costly stainless steel chain is made from.AISI 316. The best that can be expected from it is Grade 30 but this may well be sufficient for your needs. I agree it offers many benefits at x4 (?) the cost.
Many liveaboards now buy Cromox chain that is grade 50 or 60. There is a 316 version made from hard-drawn wire or a duplex version that is heat treated. Both are even more expensive but justifiable if your whole life is spent aboard

Thanks. Ours was an offcut, so cost not such an issue. We wanted clean, and enough quality for our fairly light use. Jimmy Green had some in their end of reel bin.

 

[WindyWindyWindy]

The part that is always on deck between anchor and windlass?

The anchor lives in the locker as the roller fitting is too short to leave it on there.
So it's in a similar environment to the rest of the chain but on top so perhaps drier.