Hauled the boat - What's this on my keel? - Page 2 - SailNet Community
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post #11 of 14 Old 01-22-2014
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Re: Hauled the boat - What's this on my keel?

If previously repaired blisters happen again it usually means the prep was incomplete and/or moisture remained before the wound was covered. Also can be poor material, i.e. bondo which is just a quick cover that won't last.
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post #12 of 14 Old 01-22-2014
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Re: Hauled the boat - What's this on my keel?

Originally Posted by afrinus View Post
Hi Paul

Isn't that the exact reason to put on an epoxy barrier coat? - Preventing future osmotic blister problems.

I dont have a major problem (other boats in the yard with 1000's of small blisters), but there has been blisters on on the boat in the past (there's 6 previous repair sites).

When would you consider a boat to have a "blister problem"?
A blister on an iron or steel keel has a different cause and a different remedy from a blister on the fiberglass hull of a boat. The latter is an osmotic blister. The former is not. I had a boat with a cast iron keel for many years, and it developed blisters on the keel, under the paint, every year. I tried every treatment available to prevent the blisters, but without success until I attached a sacrificial zink to the keel.

My suggestion is to attach a zink to the keel. Remove any loose fairing material. If you tap around the damaged area with a hammer, it will ring wherever the fairing material is firmly attached, but it will have a dead sound wherever the material is loose. Next, I used a wire brush bit in an electric drill to get the damaged area as clean as possible. Then I sprayed a coat of rust reforming paint on the damaged area, to temporarily cover any exposed metal. Then I filled the damaged area with Marine Tex, or a similar filler, sanded it smooth, and finally, covered it with antifouling paint.
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post #13 of 14 Old 01-23-2014
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Re: Hauled the boat - What's this on my keel?

sailormon thanks

Im about to do this to my iron I beleive keel on my islander 36 I have a big blister that cracked at the hull keel joing and it will need either anti corrosive paint forst or some sort of converter

Ill take pics if anyone is interested

thanks for the tip of the zinc

never have put one on an actual keel

Merit 25 sold...Islander 36 still afloat? who knows...Im still in Columbus, and back...I think...jajajaja!!!!
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post #14 of 14 Old 01-23-2014
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Re: Hauled the boat - What's this on my keel?

Originally Posted by CalebD View Post
It seems that Beneteau used some kind of steel in their keels. What were they thinking?
I have seen a Bene 505 keel up close and the steel/iron rusts if not properly coated. The rust would cause the paint to fall off.
An optimal repair would be to remove most of the rust/oxidation, then barrier coat and paint.
I can't quite make out any ridges in the photos.
Caleb helped me out with the keel on our Beneteau 505. I posted a thread on it about the difficulties. A few years later now and i've developed a great procedure for recoating the keel when there are problem areas. The key ingredient is Corroseal. It can be special ordered from Home Depot. I heard that is what the commercial guys use on big steel boats, but don't know first hand.
Grind away old layer (Wear eye and breathing protection)
Wire brush to clear metal (Wear eye protection! Wires fly out!)
Towel-off all dust and wipe with Xylene (Always wipe Xylene toward bottom paint. Use paper towels and the expensive, "stiffly thick" rubber gloves. Use the wind or a big fan to move air so you don't breath-in any Xylene.
Apply Corroseal
Apply barrier coat (Interlux 2000e)
More coats of barrier coat
Bottom paint

Easy peasy.
I have 75 hours of grinding and wire brushing under my belt from this. The above is fantastically better than previous approaches. Forget Ospho and forget the 2-part Interlux etch primer.

Note that there is timing involved. For instance, apply bottom paint within XXX days of barrier coat or you must apply another layer of barrier coat. Also YYY days max between barrier coats or you must sand. It takes a few minutes for the 2 part barrier coat to setup. Those measuring cups from West Maria are great to use when mixing the barrier coat.

Hope that helps.


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Last edited by Bene505; 01-23-2014 at 07:03 PM.
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