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post #1 of Old 08-26-2000 Thread Starter
Tom Wood
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Gelcoat Repair

My 1978 Cal 2-29 has developed little dime size chips or ulcers in the fiberglass that take out the white part of the glass, leaving just the darker unfinished glass beneath. How can I fix this?


Tom Wood responds:


You've got a tough one there. Without seeing it first hand, it sounds like the gelcoat is delaminating from the skin coat. Gelcoat is rather brittle, becoming more so with age. The underlying fiberlass, while certainly strong, does have some flexibility. This creates a situation where a hard surface is coated over a more flexible one, and as they age, every little stress shows up in the harder material—in this case the gelcoat.

My guess is that when the boat was built, the gelcoat was allowed to cure just a tad too long before the skin coat was laid into the mold. This made a poor bond between the gelcoat and the fiberglass—good enough for 22 years of service, but now the piper has arrived. The weak spots will probably continue to "pop" off in dime-sized pieces as the bond continues to weaken every time the area around it is stressed. That can be from as little as a foot tread.

How to fix it? If you insist on always having a Bristol appearance, get a Dremel tool, acetone, rags, putty knife, gelcoat paste in a matching color, a sander, electric buffer, sandpaper, and buffing compound—oh, and don't forget the wax. Grind out the chip to roughen the edges and base, making sure that the rest of the adjacent gelcoat is in good condition. Clean out with acetone, activate a dab of gelcoat, and press it into the bare spot firmly and evenly. After it cures, sand and buff to blend with the rest of the area—re-fill if low spots remain, repeating the process. Wax when finished.

Now, if you can stand a less than perfect boat for some period of time, fill in the same way using a polyester filler like America's Cup, or an epoxy filler like Marine-tex, following the same procedure. After you feel like you have enough blotches on the deck, have it painted for a brand new look. But don't be surprised if the first dime pops up a month after you paid good money for a paint job.


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