Primer for cast iron keel

Daydream believer

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The good quality scrubbable AF isn't actually any cheaper than coppercoat.
Coppercoat does not perform any better either. However, coppercoat just needs jet washing start & mid season, plus abrading every 3 years. The mid season haulout offsetting the cost that would be normal antifoul, so no extra cost. But antifoul paint involves a lot of maintenance & hard labour. It also depends how much time you have to spend doing it if you apply paint yourself.
I do the keel in paint, as coppercoat seemed useless on CI, but coppercoat on the main hull. A fin keel is fairly easy to do. In my case it is only about 3 M2 in area. I can do it sitting on a chair, so no grovelling on the floor, reaching over my head.
Bilge keels would be a different story though.
 

GHA

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Receiving conflicting advice on this.
I've got a cast iron keel which has previously shed its coatings. Going to try taking it back to bright metal and priming.
I don't know if I can get it blasted but I'll look in to that as it's seemingly much better.
Some suggest using standard epoxy straight on to the bare metal, which is tempting because there's never any harm in having epoxy in stock.
Someone else has suggested products called Ameron or Corotech which are more specialised epoxy primers.
And then there's stuff like the Epiphanes primer which has zinc in it, which sounds good.

Any thoughts? Boat is a 70s Moody if that makes any difference!
Trouble with cast iron keels is they are full of contamination to varying degrees unlike steel hulls so depending how dirty the cast iron is on yours you might just have to put up with touching up. Other peoples success doesn't mean that much either, might it was cleaner cast iron.
Though what is just incredible stuff if you can find it is amerlok sealer which was taken over by PPG , not even sure they still make it. Never found any in Europe, last time was in chaguaramas. Tried a few tests over the years on unprepped steel & it takes a couple of days to go off but seems to get right in there, by far the best first coat found in nearly 20 years cruising on a steel boat. If you find any let me know 😁

Think this is it if PPG still make the same stuff
https://docs.td.ppgpmc.com/download/933/2454/amerlock-sealer
 

Sea Change

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Coppercoat does not perform any better either. However, coppercoat just needs jet washing start & mid season, plus abrading every 3 years. The mid season haulout offsetting the cost that would be normal antifoul, so no extra cost. But antifoul paint involves a lot of maintenance & hard labour. It also depends how much time you have to spend doing it if you apply paint yourself.
I do the keel in paint, as coppercoat seemed useless on CI, but coppercoat on the main hull. A fin keel is fairly easy to do. In my case it is only about 3 M2 in area. I can do it sitting on a chair, so no grovelling on the floor, reaching over my head.
Bilge keels would be a different story though.
I've got experience of both ablative AF and CC so I'm aware that CC isn't a panacea.
What I really like about CC is that I can jump in the water and scrub it as hard as I like with a stiff brush, as often as I need to.
As a full time liveaboard I'm time rich and money poor and it's quite acceptable to me to do an in the water hull clean every few weeks. But anything that involves hauling out is not acceptable.
 
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Sea Change

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Trouble with cast iron keels is they are full of contamination to varying degrees unlike steel hulls so depending how dirty the cast iron is on yours you might just have to put up with touching up. Other peoples success doesn't mean that much either, might it was cleaner cast iron.
Though what is just incredible stuff if you can find it is amerlok sealer which was taken over by PPG , not even sure they still make it. Never found any in Europe, last time was in chaguaramas. Tried a few tests over the years on unprepped steel & it takes a couple of days to go off but seems to get right in there, by far the best first coat found in nearly 20 years cruising on a steel boat. If you find any let me know 😁

Think this is it if PPG still make the same stuff
https://docs.td.ppgpmc.com/download/933/2454/amerlock-sealer
Seems to be available in the UK but not at the chandlers here in Sint Maarten. There's a more specialised paint place over on the French side, I'll see what they've got before I make any decisions.
 

GHA

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Seems to be available in the UK but not at the chandlers here in Sint Maarten. There's a more specialised paint place over on the French side, I'll see what they've got before I make any decisions.
Promain used to do it but not now, searched high & low and found none in Europe sadly, email to PPG said the same. Its more on the "industrial" side of things rather than leisure marine so if there is any might be just in bigger places like chaguaramas where I got some in a dedicated coatings supplier dealing more with ships I think. While ago.. might be gone now.
So hard judging epoxy, you need like 4 boats & ten years to test a few brands against each other. One's enough 😁
 

coveman

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Update: the yard don't offer blasting. So grinding it is.
This is making me wonder if I should reconsider my approach. I should maybe see how the keel looks after we lift out. Still not sure whether to try coppercoat or a different AF. The good quality scrubbable AF isn't actually any cheaper than coppercoat.
You don't say where you are based but you may be able to find a mobile blasting company that can do the job. In my experience that is a lot more successful than grinding. My boat was coppercoated several years ago and is still working but the keel needed redoing. On the advice from coppercoat, I had the keel blasted by a mobile unit and then gave it several coats of Hempel High Protect 11 followed by 5 coats of coppercoat. So far so good but the primer needs to go on as soon as possible after blasting ( within the hour) to prevent rust particles forming on the keel surface. If you can't find anyone to blast the keel then a rotablaster works well - Surface treatment with rotating discs instead of blasting
 

Sea Change

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You don't say where you are based but you may be able to find a mobile blasting company that can do the job
We're lifting out in Carriacou so it's almost certainly a non starter to bring someone in from mainland Grenada.


If you can't find anyone to blast the keel then a rotablaster works well - Surface treatment with rotating discs instead of blasting
Those look serious! We're flying back to the UK for the summer so assuming they're not considered offensive weapons I can bring a few back with me 😂
 

MikeCC

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I prepped mine with mix of Tercoo, wire wheels and polycarbide pads (all powered!).
Filled any obvious voids with 2-pack filler and sanded back.
When I was ready, did a final clean to remove fresh surface rust and wiped down with thinners. No Fertan type product - couldn't see the point.
Straight away a coat of a 2-pack industrial underwater zinc primer, mixed ready to go, followed by two more with suitable gaps. Sanded back, then two coats of Hempel 2-pack Light Primer. Bit of filling and fairing with Profair. Coat of underwater vinyl primer then antifoul.

That was 3 years ago and apart from ploughing marks on leading edge and a couple of annoying voids in the casting, no rust breakthrough.
 

MikeCC

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We're lifting out in Carriacou so it's almost certainly a non starter to bring someone in from mainland Grenada.



Those look serious! We're flying back to the UK for the summer so assuming they're not considered offensive weapons I can bring a few back with me 😂
Very good for getting old paint and filler off. They come with 1, 2 or 3 rows of teeth and 2 or 3 is better. I used polycarbide disks for a final finish to get last bits off. They (polycarbide ) do wear quickly so have a few to hand.
 

coveman

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We're lifting out in Carriacou so it's almost certainly a non starter to bring someone in from mainland Grenada.



Those look serious! We're flying back to the UK for the summer so assuming they're not considered offensive weapons I can bring a few back with me 😂
I think you will only require one! Recommended to me by a repair yard as that is what they use. Good luck:)
 
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