I have a very thin hull, made from poly-ester resin under GelCoat. The GelCoat has a few minor spider/spliter cracks, most are cosmetic, but 1 may have penetrated into the glass, due to flexing. I'd like to open it up and repair the area behind the GelCoat and strengthen, perhaps add or replace ribs/stringers if needed. I want to add a little weight as possible and will be working through a hole that will need to be covered and cosmeticaly fixed. Question is, what resin options should I be using ? After some research I find there is polyester, polyvinal, and epoxy. I've also found that there are chemical and physical bonds, and at least my first layer will be a physical bond. I've read differing conflicting reports about putting epoxy over poly and vs versa. On the inside it does not have to look perfect, it won't be seen, but I do want a strong bond that will not peel.