Here is a "profile" of a blistered hull. The fibrous, white ring is hydrolized or water-damaged and will need to be replaced.
A water-lubricated electric peeler can be used to remove glass.
After peeling, a hull should be dried at length and tested for water content with a moisture meter.
Workers add new layers of laminate to this peeled, dried bottom. Once cured, the new laminate will be faired with power sanders and then barrier-coated.
After several layers of vinylester resin have been applied as a barrier coat, new bottom paint is rolled on.