After determining the depth of the problem, we advise a boater whether a spot repair or a total peel would be the best way to proceed. We will often suggest a spot repair in cases where there aren't too many blisters, and not large enough, but in cases where the blistering is very widespread the best results will be achieved by getting rid of the top layers of laminate and beginning the repairs at that point.
When there are a lot of blisters, you sort of have to connect the dots and assume that high-pH material has worked its way out from the areas directly under the raised gelcoat. Too many spot repairs and you wind up with a total peel job anyway.