Re: Fiberglass blisters... Boat Leprosy??
Boat pox? No, I don't think it is so serious, as others noted. All blisters are all repairable, even the serious ones (although they are a lot more trouble). Even better, most blisters don't need drastic measures to remedy as other noted previously. Dig out the compromised material, let the divots dry over the Winter, fill with a good epoxy-based material (e.g. thickened epoxy) and fair them, then protect the hull with a good epoxy barrier coat such as Interlux Interprotect 2000E or equivalent.
So long as the barrier coat is not compromised by grounding or collision with something underwater like a deadhead, no more problems. That worked for my '84 and many other boats of the era.
T. P. Donnelly
I sold my sailboat and am no longer active on Sailnet