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Forums / Restoration / Gelcoat crazing and painting  
The discussions for this thread include the following:

Posted: 09 Jun 2010 at 9:20pm
Hello everyone,
I'm getting ready to paint hull #227's deck, I've got EVERYTHING stripped and am ready to start sanding.

I'm planning in using interlux's one part paint...but I have heard that the two part lasts a whole lot longer, so I may decide to use it instead. I don't think I want to do this again any time soon.

I've noticed alot of crazing in the gelcoat, should I be sanding all of the gelcoat off? or fill in the cracks with fairing compound/thickened epoxy?

any opinions?

Posted: 20 Dec 2010 at 3:39pm
You've almost certainly gotten you deck repainted by now, but since you may be looking at repainting other parts of your boat, I'll offer my opinions in answer to your questions, FWIW. I'm not a pro, just a duffer who wants to make his boat look nice.

I'm in the midst of a cosmetic restoration on my current boat, not a Dolphin but a mid-70s fiberglass boat all the same. I've just finished prepping the coach house for paint, actually got on the first coat of finish paint (one part polyurethane) before it got too cold to finish. I had lots of pockmarks and cracks in the gelcoat. The pockmarks I ground out, filled with thickened epoxy, sanded fair, primed and painted.

The fix for gelcoat cracks, I think, depends on what caused them and how big/deep they are. I had several very fine isolated cracks which I was pretty sure were simply due to limited flexing in the fiberglass panel which had occurred over the years. These were simply sanded smooth and primed over with three coats of the epoxy primer (Interlux Epoxy PrimeKote) I used for the whole coach house. Deeper cracks I widened and deepened with the sharp end of a bottle opener, then filled with thickened epoxy, primed, etc. In areas where there were a number of cracks close together, I found it more efficient to grind out the gelcoat and fill/fair the whole area with thickened epoxy, then prime, etc. In those areas where you have lots of gelcoat cracks close together, keep in mind that there may be something more sinister going on. If you have an area with a number of somewhat circular cracks emanating concentrically from a single spot, that spot may have been the site of a significant impact injury sometime in the past; make sure the underlying laminate is not damaged. If it is, you'll have to repair the laminate or else the gelcoat cracks will come right back. Similarly, if you have a number of gelcoat cracks radiating out from the juncture of two panels that join one another at a sharp angle (for example, where a fiberglass coaming joins the cabin bulkhead), that may be indicative of inadequate structural support of one (or both!) of the panels involved (e.g. perhaps due to rotting of the plywood core of the bulkhead where it sits on the hull, a not-uncommon problem of boats of this vintage).

I'll also offer a "lesson learned" from my project, again FWIW. If you find yourself needing to grind out a section of gelcoat, don't be timid about it. When I started, I tended to grind out the smallest possible area, thinking this would no doubt be better. But after the initial filling/sanding cycle, I often found myself having to go back with the grinder to take off more gelcoat, either because the gelcoat was flawed farther out from the initial defect than I realized, or because I needed a bigger area to allow an adequate taper so as to be able to fair in the filler better. I later started grinding out a bigger area from the outset, and I found it gave me a better repair with less time spent. So, if you're going to grind gelcoat, BE BOLD, my friend! There are few things you can do on a boat that are more manly than going at it with a power grinder with 60 grit paper! (Just remember to practice safe sanding - safety glasses, hearing protection, respirator mask with fine dust filter, etc.) Have fun.

David Blakey
VintageCat 22
Norfolk, VA

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