I agree with Mike and would not barrier coat a boat if (1) the blisters are few or (2) the moisture is coming from the inside. The blisters I had were numerous, and very small (1/16" max), made by tiny air bubbles near the surface of the gel coat - almost like a rash. If moisture is inside, that should be fixed. I cold-molded a boat with West System - great product. The advantage of Watertite and Interprotect 1000 below the WL (so they say), is very high solids content so the chance of unreacted residue, that leads to blisters, is reduced.
