rusting anchor shackle & chain

[steve yates]

Is this caused by stainless being attached to galvanised? or just water in the anchor locker?





If I just replace the chain & shackle, what can I do to prevent it happening again?

Thx

 

[RichardS]

Water in the anchor locker exacerbated by wet rode underneath is my guess. Any galvanic effect between stainless and galv would be isolated to the first link or two, although my chain is kept in a dry locker and after 10 years there has been no sign of trouble from the stainless swivel.

Richard

 

[steve yates]

Thanks richard, thats good, I rather liked the swivel

 

[Boathook]

Could try using fresh water to rinse the chain and rope every so often or even after every trip if you are in a marina. I suspect that a lot of the damage is caused by the salt so the new one will eventually go the same way.

 

[Neeves]

There is an excellent article on anchor lockers and chain in the May 2019 edition of SAIL. I'd offer you a copy but I have not seen it myself yet. SAIL takes some time to arrive down here - it might already be available in the UK

Summarising some points,

Washing the chain with fresh water, when you rinse down the decks, then keeping the anchor locker dry (open the hatch when the weather is good), add a grating to the locker base so the chain dries, don't store with wet rope, make sure the drain hole is clear - all help.

Corrossion, any, needs moisture -keep it dry.

Muds can be anaerobic, organisms within the mud secrete sulphur compounds (hence the smell) that convert to sulphuric acid. The acid will remove your galvanising - wash the chain of mud. When there is a particularly 'bad' mud it can make your chain go black. On no basis I suspect an acidic damness may increase the speed of any galvanic corrosion.

It is very common for the first few links to suffer from accelerated corrosion, the shackles (and on better anchors also the shank) are a different steel chemistry to the chain which appears to increase corrosion. it is common practice to chop off the first few links every few years.

Keep the locker and its contents clean and dry.

That really is a cheap and nasty swivel! I've tested them - I would never, ever, use one.

http://www.mysailing.com.au/cruising/how-to-boomerang-your-anchor-right-back-at-you


Jonathan

 

[FairweatherDave]

I don't know your anchor locker Steve, but on my Westerly Konsort when I bought it I found exactly the same problem with a chain/rope mix. I subsequently converted to all chain,( which if too long can effect the boat trim ) . But as Neeves says empty the locker. Mine was blocked up with mud so could not drain (into the bilge as designed). I toyed with Neeves idea of a grid but compromised by placing a large round stone (the size of two fists). Plenty of space to drain around the stone out the bottom of the locker. But I also empty the locker once a year to check it is still clear to drain.

 

[Neeves]

I'm not sure about adding a stone, I'd rather the weight was in chain - but I like the concept, maybe a hard plastic float )(which you can use if you ever need to abandon, temporarily, your anchor and rode .

Another idea - try to keep the rope portion of the rode separate to the chain. The rope will hold water and will be a devil to completely wash of salt water. Try to store, maybe hung on one side of the locker, 'somehow' in the locker hatch/lid - but a wet rope mixed up with chain is a recipe for rust. The ideal are a separated locker, rope on one side and chain the other (preferably chain slightly aft - but most lockers appear to be an afterthought - simply the inconvenient (very small) space left after they have crammed in all the accomodation.

Taking all the chain out, washing it as often as you can will prolong chain life and if you 'winter' the yacht ashore - string the chain up like washing between the cradle supports or acrows.

I see new(ish) chain in newish yachts covered in a white crusty coating - this is white rust - some compound of Zinc - its your galvanising being eaten - simply because the chain is damp/wet. You don't actually need to use the chain to lose gal!

Within reason - keep it clean, or salt and mud, keep it dry (or allow it to dry).

Chain does not last for ever - and when it needs replacement one quickly identifies its not particularly cheap.

Jonathan

 

[vyv_cox]

Jonathan is absolutely right about the swivel. Although sold by yacht chandlers they are not built for anchoring. Most are made in Spain for the fishing industry. One of them was by far the worst performer in my test series. Results on the website.

 

[Boathook]

Thanks richard, thats good, I rather liked the swivel

I didn't notice the swivel first time. I had one like that and got rid of it. I went for a Kong ( https://jimmygreen.com/anchor-connectors/27472-kong-swivel-anchor-connector-stainless-steel-aisi-316 ) .

 

[steve yates]

Thank you all, the swivel shall be binned
This is on my little 18footer, not the longbow, so all chain would be too front heavy an option I suspect.

 

[Neeves]

If you used 6mm chain you could keep it in a bucket and would not need the rope at all. It would be much easier to keep clean (as you could take the bucket ashore) and dry. It could then be stored centrally and you would not need to worry about weight in the bow. 6mm chain is, obviously, smaller than 8mm and is not unpleasant to retrieve by hand, its both lighter (again - obviously) but also more 'tactile'. You don't mention the weight of your 18' but I believe 6mm is available galvanised from Grades 30 to 70.

If you have problems finding shackles to fit - send me a PM and I'll suggest a 'personal' solution.

We are using a 'one off' galvanised G80, 6mm, 75m (with a Maxwell windlass) on a 38' x 7t cruising cat (and I have spare connectors). The chain and connectors have all been tested and are the same strength, or greater, than 8mm G30.

Jonathan

 

[Greenheart]

I acquired some chain which I was inspecting last week. A few rusty links, but not as serious as Steve's photos show.

All the same, is there any reason not to grind out the bad links and join the good sections with shackles of equivalent size? I have no expectation of using a winch, so the regularity of link-size isn't an issue.

I've seen those half-links which look clever, but I've never heard anyone state they had relied upon them, so I'm wary of the idea.

 

[vyv_cox]

C-links are perfectly OK if you select the right one. Crosby are good, sold by lifting and hoisting specialists. Lots of info on them on the website.

 

[Neeves]

I cannot source the better of Crosby's shackles, their G209a, in Oz and on, I think Vyv's suggestion, I contacted Tecni in the UK, https://www.tecni.uk . They have supplied what I need and post to me normal air parcel post (so no exorbitant courier costs). They may supply Crosby 'C' links.

Interestingly - Crosby seem to command this market, in terms of quality - I have never heard of anyone else being 'approved' (but then apart from Vyv I don't know anyone who has tested one/them).

I have never used a 'C' link, nor tested one - Vyv's work and conclusions are proven and enough for me. Its too expensive to reinvent the wheel!

It might be mentioned on Vyv' site (I was too lazy to look ) - but don't be clever and try to heat them, for any reason - like welding, you will destroy some of their strength.

Jonathan

 

[vyv_cox]

The only reasonable looking alternative I have found is the one sold bt West Marine. It says all the right words but I was unable to test as they wanted $70 to send me one! Now it has become even more difficult as I cannot see the West Marine website due to data protection.

 

[Greenheart]

Thanks for all the replies about "missing" links, and links to Vyv Cox's excellent website. The pic I included above was found on a website advertising the item at under a fiver...

...Crosby's equivalent from Jimmy Green, seems to be five times the price. Happy as I am to make logical economies, the fairly tired old chain I have acquired may be more sensibly replaced, than repaired at significant cost. :encouragement:

 

[Neeves]

...Crosby's equivalent from Jimmy Green, seems to be five times the price. Happy as I am to make logical economies, the fairly tired old chain I have acquired may be more sensibly replaced, than repaired at significant cost. :encouragement:

Tecni may be cheaper but

I did want to say so

But you have taken the words, almost, out of my mouth.

I trust Vyv's work, without question - but could not quite steel myself to use one (no pun intended).

Irrationally,

Jonathan

 

[Greenheart]

Thanks for that.

So, my original question; given that I don't anticipate anchoring in severe weather, or using a chain gypsy, how inadequate is the strength of a decent shackle (of which I have plenty) for linking chain?

I realise that relying on anything but a costlier solution (such as replacing the whole rode) is for fair weather only; but I'll endeavour not to be at sea at all if it's blowing hard.

 

[steve yates]

If you used 6mm chain you could keep it in a bucket and would not need the rope at all. It would be much easier to keep clean (as you could take the bucket ashore) and dry. It could then be stored centrally and you would not need to worry about weight in the bow. 6mm chain is, obviously, smaller than 8mm and is not unpleasant to retrieve by hand, its both lighter (again - obviously) but also more 'tactile'. You don't mention the weight of your 18' but I believe 6mm is available galvanised from Grades 30 to 70.

If you have problems finding shackles to fit - send me a PM and I'll suggest a 'personal' solution.

We are using a 'one off' galvanised G80, 6mm, 75m (with a Maxwell windlass) on a 38' x 7t cruising cat (and I have spare connectors). The chain and connectors have all been tested and are the same strength, or greater, than 8mm G30.

Jonathan

Thanks jonathan, Bethfran is 450 kgs displacement with 180kgs ballast, so around 750 kg unladen if I have that right? She will come in at just under a tonne when fully laden I would guess. I like the idea of the chain in a bucket or a gardening trug, but I do have an anchor locker and want it kept there as it will be used a lot. She is too small to have more "stuff" in her cabin area than necessary The anchor is a 7kg delta attached to the chain and then mainly rode

A cut down trug may well fit in the locker with space for the rode and anchor too, which will keep them separate, I'll have a go at that.

A dumb non diy'ers question, If I am going to cut the rusted shackle off with an angle grinder, I presume I really want the shackle or whatever i'm cutting held in a vice? It's not like taking a haksaw to it?

 

[Neeves]

A dumb non diy'ers question, If I am going to cut the rusted shackle off with an angle grinder, I presume I really want the shackle or whatever i'm cutting held in a vice? It's not like taking a haksaw to it?

Angle grinder? Why not a simple pair, are they called a pair?, of bolt croppers.

But, yes, the shackle needs to be retained, firmly - especially when addressed by an angle grinder wielded by someone lacking enough confidence.

I'm going to show long it been since I was in the UK -

I don't know what they are called - but one of the work benches that fold up with the table top a sort of big vice. A 'G' clamp, A paving slab. A mole wrench (are they still called mole wrenches?), under a paving slab. None of these are 'techniques' I would support for frequent use (except for the bolt croppers) - but it is one clevis pin, only - and if you have an angle grinder you are more than a non diy'er than you admit. (They must be the most dangerous tool in a DIY'ers toolbox

Its easy - but I cut chain with bolt croppers

Jonathan