Gelcoat over extensive area

[March]

We cracked the centerboard two weeks ago in the Apostle Island, hitting an underwater boulder. I removed it from the boat, fiberglassed the crack, sanded the patch down smoothly. Initially, I thought I would leave it semi-transparent in places cuZ no one is going to see it anyway, but then it dawned on me that naked fiberglass might be slightly hygroscopic and that's why it's gel-coated to begin with

What is the most effective gelcoat you guys recommend, for an area, say, as wide as four outstretched palms (both sides of the CD)? For smaller patches, I have used Marine Tex successfully (covered with a bit of scotch tape which reduces the need for sanding) but this is too wide an area.

The other day, I saw at Home Depot a product for covering hairline cracks in a porcelain sink or refurbishing a scratched bathtub. Wonder if that would work for fiberglass, too

[kadet]

Most Gel and Flow coats are not waterproof either as they are polyester. You need vinylester or epoxy for water proofing. For a trailer sailer this should not be a problem unless you store the boat at a wet dock. Personally I would just use a 2 pac epoxy paint.

[seahouse]

If it's already sanded smooth and flush, use a white spray paint primer (automotive works over fibreglass), and follow it with a similar shade of spray paint. Touched up a scuff in the tip of my rudder that way a couple of years back. Happened to match perfectly. I forgot I had done it (haven't noticed it, pretty much invisible) until you just brought it up.

[mastreb]

For the daggerboard, none of this matters. Even if the FRG was completely wetted through from absorbed moisture, it wouldn't matter as the dagger fills with water anyway. Nobody ever sees it. Frankly I wouldn't bother.