This is an important thread, with lots of good info for folks faced with this kind of repair. Having done this both from the top and from underneath, I add my vote to the "it's better on top" crowd. Maybe if the area is open enough to allow good bracing, or you're already into the equipment needed to do vacuum bagging it makes sense to do from underneath, but for most of us, that's not the case. hen working from above, you're not fighting gravity and everything you need to access can be gotten to easily.
I totally botched an underside repair, which I atempted to try to preserve the non-skid. Because it was where the chainplates pass through the deck, I decided to make it solid glass so that there would be no core to rot in the event of future water incursion. I used thickened
epoxy expecting it to hold each layer glass in place until it set. The glass sagged, and while I was trying to smooth and it up from below, the
epoxy hardened, leaving voids. So I ended up filling the voids from above with
epoxy, drilling holes into the non-skid I was determined to preserve. The uneven nature of the glass I had laid in from underneath allowed the thin
epoxy used to fill to run down into the cabin. I had to take an epoxied piece of plywood that I covered with very thickened
epoxy to put a layer underneath to seal it all up so I could fill from above. The space was so constrained that I could not block the plywood in place from below, so I had to drill through the deck and use screws from above to hold the plywood in place until the
epoxy cured. Now I had more holes to fill. I should have ground out my sgged glass and started over, but by this time I was too far along. It eventually worked out, but I'd have been done days earlier if I had just gone in from above.
The above story was for a 10" by 16" section of deck. I recored the entire fore and aft decks of my Typhoon from above in less time than this small repair took from below. But individual results may vary.
John USYacht 27 "Cora Lee"
Linear Mode
