A reader's question about sealing a keel root answered by one of PBO's experts

QUESTION: 

My fin-keeled Jeanneau Sun Odyssey 32.2 has some rust stains from the hull-to-keel joint. Last year I replaced the original sealant with TEC 7, but with no improvement. Is a possible solution to grind about 35mm on each side of the joint and seal it with glass cloth and resin?

Stener Meldgaard
Denmark

COLIN BROWN REPLIES:

There will always be some movement when a heavy iron keel is bolted to a slightly flexible hull structure, and eventually the original sealant will break down and allow water to enter the hull-to-keel joint and cause rust. If only the outer edges of the keel are affected this is only a cosmetic problem, but if water has reached the whole keel top then the studs which hold the keel on could be affected.

The common cure would be to clean the keel edges as best you can without damaging the glassfibre of the hull, apply primer and re-apply flexible sealant. Do not apply glass cloth and resin over the joint as this will crack and break off as the joint moves, leaving no seal at all.

The only way to be absolutely certain of curing the rust streaks and ensure that your keel studs are not affected is to remove the keel, clean the keel top back to bare metal and apply a suitable primer before resealing with flexible sealant.

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