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post #1 of 4 Old 08-01-2007 Thread Starter
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In Deck Moisture - Fixes?

I bought a used boat a month ago and the survey went very well. Been sailing on her a few times and really like it. The boat is a 79 Pearson 10M

The surveyor found a few small areas that had high moisture (red) on the deck. 2 of the areas are near the cockpit opening/deck intersection near the deck/hull joint on either side of the boat. Guess is that these areas are less than 2 square inches each. The other problem area is the back deck on the transom where there are a lot of fittings and such. Each of the areas has a few drill patch holes from either other previous fittings or moisture. The back deck may have some wet/partially rotted core.

His suggestion for the fix was to drill out the exisitng patch plugs as they have small cracks in them and repot with 4700? adhesive/potting compound. Over time the trapped moisture will permeate through the fiberglass and the deck core will eventually dry out.

The two side things are no biggie, but the back has a bigger area of moisture with the core getting black (viewed from the underside), so I want to fix this this weekend.

For the back, I was thinking of drilling out the existing plugged holes and putting some very small (1/16") holes in the problem area. Through the larger holes I would inject thin epoxy until it squirted out the weeping holes, allowing to it then cure, then drill some of the epoxy in the plugs and weep holes out and back filling with gel coat to try and match the offwhite transom. The epoxy would react with the water and stiffen everything up and stop the rot.

Plausible? Other ideas?


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"Over time the trapped moisture will permeate through the fiberglass "
That man is delusional. When and if moisture can manage to permeate through the fiberglass, it will have long since destroyed everything in the core first.

Check out the Gougeon Bros / West Systems web site for instructions on how to deal with this. If the areas are small, you can drill some holes, dry out or remove the damp coring, and then repair those areas. But simply resealing them to trap the water that's inside--that's nuts.
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post #3 of 4 Old 08-01-2007
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After drilling out the holes and before filling them with thicken epoxy, it may be a good idea to place an old angle/key wrench in the drill and use it to remove some more of the core, between the fiberglass. This way you get more epoxy into the deck with smaller holes. Remember to duck tape the back side of the hole before injecting epoxy. If you need to rebed any deck fittings, use a countersink on the epoxy filled holes. It will aid in stopping leaks and give a place for the bedding compound to go.

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post #4 of 4 Old 08-01-2007
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Umm... leaving moisture inside the deck core is a really bad idea. It won't necessarily migrate out in the direction you want... and as long as there is moisture in the core, rot and delamination are both strong possibilities.

Drilling holes in to the core material and letting it dry out is a good start, if the core material hasn't been wet for too long and hasn't started to rot. If the core material has started to break down, especially plywood and balsa, you will need to either replace the core material—re-coring the deck, which is a fairly involved project or inject thickened epoxy to try and rebuild the core material's strength.


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