hull prep question
OK, I have removed about 20 years of bottom paint from my ''71 fiberglass sloop and am down to what may be a barrier coat. It does not look like gel coat; it is grey and very hard. Where the fiberglass keel stub meets the external lead ballast there is one area where my sanding (to make the glass stump fair with the lead portion) has gone through the grey layer and revealed what looks like the lay-up: I can see blue fibers within a clear matrix; it is very hard and smooth - no fiberglass "hairs" sticking up. Could this be layup saturated with epoxy? Do I need to barrier coat this area? Should I barrier coat the whole hull, even though not even one blister of any size has turned up? Thanks for any advice.