I agree you want epoxy, not polyester or "Bondo" brand resin. Epoxy has a very good secondary bond to polyester (ie fibreglass) where polyester only sticks well in a wet layup where the previous layer hasn't fully cured. Here's a link to West Epoxy's fibreglass repair manual
http://www.westsystem.com/ss/assets/...aintenance.pdf and most applies to any brand of epoxy.
sailingbud - $60 a gallon? Where? I spend that for a quart of West Epoxy.
Brian