Issues with Coppercoat on cast iron keel - need some advice

[benzy]

Thanks again for all the replies.

I guess the consensus is that there should be no rust and therefore they have done a poor job. Since we cannot get back to the yard I think the only course of action is to ask for a partial refund to cover the cost of getting this fixed elsewhere.

As for what to actually do. I will keep an eye on it and monitor if it gets worse or not. If it doesn’t get worse, then it means it is isolated to those small areas and they can be repaired. If it does get worse it means that generally the whole keel will probably need to be redone?

[Fore and Aft]

It might not be the yards fault. I bet they did not have the equipment to test the coating on your cast keel? In the gas pipeline industry we have a process called Jeeping where we have an electrified brush or coil and run it over the metal pipe after it has been coated. When the defect is found it causes a short back to the control box and beeps. You would be surprised how often there is a pinhole that is not visible to the naked eye. I am sure you could do the same on your keel.
Cheers

[Snowpetrel]

^^ thats a pretty neat bit of technology. Simple and effective. How big are the pinholes and how do you fix them?

[Fore and Aft]

For pin hole size areas you usually feather out an area about 50mm diameter back to bare steel then apply the same coating. Protol paints supply their own repair cartridges and gun so it’s real easy to do repairs, other paints you have to mix a small amount of paint. Some of the pinholes are so fine all you can see is an arc from the brush to the steel when you are jeeping.
Coating failure is is an issue and I would like to see how they did the keel? They mention the keel was blasted then filled. Unless they did a perfect flush fill then waited until the filler was tacky and rolled on the epoxy I think they might have missed the window on coating the blasted steel. I imagine they filled the keel, sanded the filler the next day and then did the coating.
Cheers

[David B]

Originally Posted by benzy

We have a Moody 376, which has a bolt-on cast iron keel. The boat’s hull had been coppercoated many years ago and the keel was regular anitfouled.

We decided to bite the bullet and get the whole thing redone with coppercoat in an attempt to avoid having to haul out each year. We figured if the coppercoat lasts 4-5 years then the extra expense upfront will have been cancelled out and every year after that is a bonus.

The main concern, having read what I could on the internet, was the preparation of the cast iron keel. The require for it to be treated properly to avoid rust is crucial. We got a number of quotations from various yards in Greece (where we are). Based on a number of cruising friends giving very positive feedback about a particular yard, we decided to go with them.

They did the following:
- Sanded back the hull
- Sand blasted the keel all the way back
- Used epoxy filler to fill the expected unevenness of the keel
- Applied 4 coats of epoxy primer to the keel
- Applied 4 coats of coppercoat over the hull and keel

They did the work over the course of 5 weeks. They let the boat dry out for about two weeks before starting work on it. They were supposedly watching the humidity and picking the best time to do the work. They sent progress photos as they went.

We returned to the boat just before they applied the coppercoat, so I had a chance to see the primed keel and to me it looked really good - smooth finish (but I’m not expert of course!)

Anyway, we launched and here we are two weeks later and there appears to be a problem. On the port side of the keel there are 12 rust spots that have appeared - like pin holes where rust is “oozing” out. On the starboard side there is on pin hole spot, and one section where a rust line is appearing along the hull-keel join.

Having reread other people’s experiences with coppercoating a cast iron keel, it seems this is not good, especially after only two weeks of being in the water. The flip side is people always say “cast iron keels are impossible to keep rust free to so things like this are inevitable”.

We don’t have an opportunity to go back to the yard that did the work, so that is not an option.

I’m trying to figure out:
1. Is this normal, or considered an acceptable outcome after two weeks in the water?
2. Is it something that needs to be fixed (ie: I can live with the rust spots, but I can’t live with the coppercoat itself becoming damaged and flaking off)?

Thanks

Just catching up on this. We had ours treated with Coppercoat back in 2012. No rust issues at all to date after now, seven years. I suggest that there must be pin-holes in the protective epoxy coating. If/when we ever have to re-do our Coppercoat, I will be ensuring the keel is sanded back to sound undercoat, then applying another 4-5 coats of high-build epoxy primer undercoat before the Coppercoat goes on.

There is an area on the trailing edge of our keel when I got an anchor chain hooked onto it five years ago. I treated it the same way, and no issues.

My suggestion is to see how your keel goes over the next year. Then when all of the spots that are an issue have revealed themselves, treat as I did for that little area the chain attacked. Just sand back to clean iron, then 4-5 coats of high-build epoxy, let fully cure (that means all solvent evaporated out also), then touch-up with Coppercoat (4-5 coats wet-on-tacky). As I have found with ours, you should be fine then.

Hope that helps.

David