by GreenLake » Sat Mar 29, 2014 8:03 pm
If your conclusion that the damage is cosmetic is correct (it appears likely, but from your description), then appearance is the main/only reason to want a fix.
You have several options. If the deck is a color you don't like, or its general appearance is far gone, then you could paint it - that would hide the cracks, but they would need to be filled and faired. Otherwise, you could try fixing the gelcoat.
Either way, you'd start by making things worse, so to speak, by widening the cracks with a scraper or dremel tool. If your next step is painting you can use any colored filler, but if you need to restore the gelcoat you would need a gelcoat repair kit, and attempt to match the color. For an off-white deck, you may find pre-tinted kits that come close (they are created for powerboats), but don't expect a perfect match.
Gelcoat has the habit of not curing unless you exclude oxygen. For a small repair, a plastic sheet works fine, for a larger repair you can get this stuff that you can paint on, and that you can wash off, when the gelcoat has cured. Stiff plastic sheet is great to help the gelcoat conform to the deck surface, reducing the need for sanding.
If all you are interested in is sealing the cracks, then you can use transparent gelcoat. The one I've used was chemically treated to cure in air. I've used it (on my DS1) in places where floorboards had worn through the gelcoat to the laminate; I wanted to seal the laminate again but didn't care about appearance. Easy to use in that kind of application.
I take it you are going to double check that the cracks don't extend into the laminate etc., and that the mast partners, or deck don't have soft spots.
~ green ~ lake ~ ~