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Old 12-06-2021, 12:45   #1
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Help!! Blisters on keel

Just needing some opinions on how best to handle my blister problem. My boat is a Catalina 250 wing keel (2001) kept in fresh water. Finally decided to pull the boat out for a bottom paint. After power washing and painting, noticed all the tiny blisters. They are only on my keel, but they are all over it. They are small, most are the size of a pencil eraser. I broke a couple open and there wasn't liquid, like I expected, but there was a little crater in the underlying layer past the gel coat. See pictures. What is the best way to fix this?
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Old 12-06-2021, 17:05   #2
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Re: Help!! Blisters on keel

This does look like a corrosion issue.

Don't see gelcoat on there. Looks more like a painted metal keel to me.

Blisters may have been caused by wrong application of copper based antifouling directly to a metal keel without barrier coat in between.
Then someone applied the blue antifouling which now gets popped by the reaction of the two metals underneath.

If you really want to fix it properly:

Sodablast or otherwise remove all paint to bare metal WITHOUT corrosion, double epoxy coat & tar epoxy it.
Re-apply underwater paint.
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Old 13-06-2021, 04:53   #3
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Re: Help!! Blisters on keel

We agree.
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Old 13-06-2021, 05:01   #4
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Re: Help!! Blisters on keel

Yeah, I was thinking, "those blisters don't look like the osmosis-type ones I've seen before..."

Just poor painting with incorrect adhesion as Franziska and Manateeman say.

That must be a relief!

Good luck with the re-do,
Warmly,
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Old 13-06-2021, 11:56   #5
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Re: Help!! Blisters on keel

Quote:
Originally Posted by Franziska View Post
This does look like a corrosion issue.

Don't see gelcoat on there. Looks more like a painted metal keel to me.

Blisters may have been caused by wrong application of copper based antifouling directly to a metal keel without barrier coat in between.
Then someone applied the blue antifouling which now gets popped by the reaction of the two metals underneath.

If you really want to fix it properly:

Sodablast or otherwise remove all paint to bare metal WITHOUT corrosion, double epoxy coat & tar epoxy it.
Re-apply underwater paint.
Correct.
You can't have osmosis/delamination on metal keel.
Just missapplied paint to be removed and repainted as quoted above.
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Old 13-06-2021, 12:24   #6
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Re: Help!! Blisters on keel

As they are not osmosis, why worry as they are not doing any harm, so just anti foul over them. The most I would do would be to grind them off, fill in and paint.
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Old 13-06-2021, 13:37   #7
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Re: Help!! Blisters on keel

Those will slow you down a good knot or two, gotta get rid of them!
Ok, just kidding.
I am pretty sure that is a lead keel, no? Not much to worry about there. Clean them out and paint over as others are saying. Just don't put on your glasses after painting the bottom and they'll look (and be) fine.
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Old 13-06-2021, 13:44   #8
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Re: Help!! Blisters on keel

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What is the best way to fix this?
It's June, put it back in the water and go sailing.

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Old 13-06-2021, 14:19   #9
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Re: Help!! Blisters on keel

Thanks everyone. I'm glad I asked. Yes it is a solid lead keel. But I think it's covered in fiberglass, or something. Not sure the thickness. But if I can just do a quick sanding and repainting with the antifoul paint, I can handle that. Was also thinking of sanding and putting a coat of gel coat on, then repainting. Not sure if it's worth all that or not?
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Old 13-06-2021, 15:40   #10
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Re: Help!! Blisters on keel

Just sand and repaint will be enough and go sailing. Even not sanding will not make any noticeable difference to the performance. Nothing is perfect.
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Old 14-06-2021, 02:38   #11
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Re: Help!! Blisters on keel

Slap dash is slap dash ,not a big fix ,do it once properly ,all done for many years ,plus it will add to your resale value ,try to sell her like that and watch the value drop .⛵️⚓️
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Old 14-06-2021, 15:52   #12
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Re: Help!! Blisters on keel

Quote:
Originally Posted by Franziska View Post
This does look like a corrosion issue.

Don't see gelcoat on there. Looks more like a painted metal keel to me.

Blisters may have been caused by wrong application of copper based antifouling directly to a metal keel without barrier coat in between.
Then someone applied the blue antifouling which now gets popped by the reaction of the two metals underneath.

If you really want to fix it properly:

Sodablast or otherwise remove all paint to bare metal WITHOUT corrosion, double epoxy coat & tar epoxy it.
Re-apply underwater paint.


Ok, I was wrong, there is no fiberglass, I scraped down a little further to the lead. Looks like the lead was painted, then an epoxy coating, then some kind of paint, then my ablative coat. Would it be bad to just sand it lightly to take off the blisters, then apply gel coat? Or just go straight to the ablative paint again? I just don't want to make a mess of things.
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Old 14-06-2021, 16:57   #13
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Re: Help!! Blisters on keel

For now? As mentioned above, I’d slap some paint on those now exposed spots and wherever else it needs and go sailing. Before next season, feel free to strip it down to bare lead, apply a wire brushed in epoxy coat, etc etc.

It isn’t iron, so corrosion isn’t an issue. This is a cosmetic/drag issue that can be corrected before next season—don’t waste prime sailing season on it.
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Old 14-06-2021, 17:09   #14
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Re: Help!! Blisters on keel

Absolutely NO to gelcoat!! Best would be to strip to bare metal, then prime and apply several coats of antifouling paint. Quick would be to send as smooth as possible and apply a coat of antifoulng.
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Old 14-06-2021, 17:13   #15
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Re: Help!! Blisters on keel

Yeah I'd echo that, no gel coat and just put it in the water as-is and sail and wait for winter to deal with it. Since you have a trailer for it, it's easy.
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