Anchor chain care - rusty bits in the middle

Yngmar

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I have 45m of 8mm galvanised anchor chain. I also have a puddle at the bottom of my anchor locker due to the drains being not quite at the bottom. Some of the chain sat in the puddle for years and has rusted, resulting in a mostly still galvanised chain with several half-metre long rather rusty bits in between.

I can fix the puddle issue by dropping in some plastic grating or something (looking for suitable cheap grating to repurpose for this), but what do I do about the rusty chain bits? Re-galvanising the whole thing seems silly when it's just a few short sections of rust in between and the rest is fine. Perhaps some "cold galvanising" zinc paint? But how do I get the rust off (no blasting equipment to hand). Does that stuff even stay on the chain for any relevant time? Is there a better way?
 

RichardS

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I have 45m of 8mm galvanised anchor chain. I also have a puddle at the bottom of my anchor locker due to the drains being not quite at the bottom. Some of the chain sat in the puddle for years and has rusted, resulting in a mostly still galvanised chain with several half-metre long rather rusty bits in between.

I can fix the puddle issue by dropping in some plastic grating or something (looking for suitable cheap grating to repurpose for this), but what do I do about the rusty chain bits? Re-galvanising the whole thing seems silly when it's just a few short sections of rust in between and the rest is fine. Perhaps some "cold galvanising" zinc paint? But how do I get the rust off (no blasting equipment to hand). Does that stuff even stay on the chain for any relevant time? Is there a better way?

Possibly cut out the rusty bit and join the good ends with a Crosby link or similar?

Richard
 

vyv_cox

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I would certainly try zinc spray paint first. Quite a few years ago my Delta anchor was beginning to rust quite badly. I sprayed it with etch primer first, then zinc paint. I used it a lot for several seasons after that and was surprised how well it lasted. The anchor is now my spare, stowed in a cockpit locker for the past 7-8 years where it has not rusted any further.

For the short lengths you are talking about I would wire brush it manually to clean off loose rust.

The only down side to painting it is that if you ever decide to have the chain regalvanised the paint will need to be 'burnt off' first, done by passing the chain through the molten zinc without it going through the acid bath first. This adds about 50% to the total price.
 

Yngmar

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Thanks Vyv, I've just ordered some zinc paint and will give this a go next time the weather plays ball (which may well be in spring). We'll see how well it holds up against the movement between links and through the gypsy.
 

Yngmar

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Finally got around to doing this on a nice sunny day this week. Spread the chain out on the pontoon, wire brushed the rusty bits as good as we could, washed it a couple times and let it dry completely.

Then brushed a can of Zinc Rich Cold Galvanising Priming Paint on the derusted bits. The stuff is extremely thick and gooey and needs a very thorough stir with a sturdy stirrer first - definitely lots of metal in it. It dries rather quickly - between the two of us we barely managed to use one small 250 ml tin before it dried out. Tried to get it in between the chain links as much as possible.

Seems to stick to the chain surprisingly well. After giving it some extra time to dry, it went through the bow roller and gypsy without chiping off, which was encouraging. Time will tell how well it works and how long it stays put.

To keep the chain from falling into the puddle at the bottom of the locker, I've cut 3 layers of thick grass protector rubber mat to size, which now lives at the bottom of the locker and keeps the chain off the floor (and makes it rattle a bit less when going in as a side effect).
 

Yngmar

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Reporting in after 9 months. The zinc paint has held up surprisingly well on almost all the chain links we painted with it (as well as a spot on the anchor).

Unfortunately on a very few links it has chipped off with further rust coming through, most likely due to having been insufficiently de-rusted before application. Generally the stuff can be recommended, definitely for the anchor or others with a few rusty links in an otherwise good chain. Will probably replace the chain though, as I want it a bit longer and would like to go up to Grade 70 to match the bigger anchor fitted.

The rubber grass protector mat works well. I've fished it out the bottom for a cleanup of the anchor locker and it even keeps the mud contained and the drains working :)
 
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