Probably cosmetic
Bud, There are 2 kinds of blisters: 1 kind is not really a blister at all, but just a void or air bubble in the gelcoat. These tend to be the size of a pencil dot, and have no moisture in them. They're often found at the waterline. They're almost always cosmetic & don't represent any structural concern, but it would be a good idea to grind them out & fill with epoxy. The other kind is an osmotic blister. They can range in size from that of a dime to the size of your palm. Sometimes they're even larger. They're filled with a putrid acidic fluid, and these will lead to major structural problems if not repaired. When people worry about blisters, it's osmotic blisters that they're talking about. It sounds to me like you have the kind that are cosmetic, not tragic. I had about 400 of them at my waterline & used a dremel tool with a cone shaped grinding stone to grind them out & then refilled with epoxy & repainted. Not that tough a job, except matching paint colors. Good luck with the new boat!! I've had a C-30 for about 5 years now & LOVE it. Allen Schweitzer s/v Falstaff C-30 Hull #632 p.s. - to get rid of the mold or mildew stains, try washing with bleach & water (about 10% bleach) and a sponge. If that doesn't do it, you might want to lightly scrub with soft scrub w/bleach. That should do the trick.
