I bought a 1989 catalina 26 last may. Excelent condition well maintained in need of bottom paint no major blistering. Pulled it feb 7th some small blisters, nothing unusual until a line of blisters just below waterline port side were ground out to find voids with no solid material just what seems to be foamboard or a fuzzy fabric but nothing solid. Has anyone ever seen anything like this? How to repair? I'm afraid to go any farther until I find help. Catalina is no help but confirm they have never used a foam core. Appears to me to be a manufacturing defect.