I started this project last year when I hauled out and found bubbles on the hull. As I have owned Discovery for 5 years and do not know her history, I decided to do a once and never again project to sand her down to the gelcoat and giver her a fresh bottom for my own peace of mind.
I found that Discovery had a primer coat, a hard coat, and ablative coat as I sanded her down. A couple of six packs of beer for the marina's painting and maintenance crews and I get some time and advice in return. The crew lead told me the three layers are what they do when they do this type of work.
BTW, Discovery did not have blisters filled with water/acid. The gelcoat was blistered and had no water/acid when opened. Dried, they look like half moon circles that leave circles when you can pick them out with a sharp knife. (*note: TotalBoat Polyester Fairing Compound to fix gelcoat blisters - great stuff).
Good talk, I appreciate the advice.
Mark "Souleman" Soule