The result is intermittent and generally poor bonding of the resins with the cloth and the gelcoat. The blisters may appear above as well as below the waterline. As a rule the vessel will have internal delamination of the fiberglass layers and may or may not have any gelcoat blisters. The delaminated areas may show up as very large blisters and the outer layer of the blister will be thick since it may contain several laminates. This is a structural problem and is difficult if not impossible to repair.
Water migrates through the gelcoat.
Blisters are located under the water line and sometimes located along the water line only. When punctured, the blisters contain a colorless liquid which is acidic. Is mainly encountered in a certain series and make of production boat. The manufacturer corrected the problem several years ago. Is rare and not typical of production type boats.