I'm doing the final sanding of the hull and deck. In a few places, the hull feels smooth, but I can see the pattern of the fiberglass cloth. I can't actually feel the fiberglass cloth, and if I wipe the hull with a slightly damp rag, the fiberglass cloth pattern disappears. However, it reappears after the water evaporates. Did I sand the resin too thin in these areas? Should I add additional resin to build up the area and then re-sand?