Had a few blisters on mine when I bought it a few years back. Last spring I had the boat hauled the blisters professionally repaired, the bottom resealed with an epoxy sealer and new antifouling paint applied. The surveyor at the time of purchase told me that the slight pox problem was not a real problem and repairing the blisters were not necessary other than to increase the value and give me peace of mind.
Boat in the PNW and I'm in the Middle East. #@%$*