[Irwin32]

When you state on the transom, does this mean above the waterline?

My 1973 Irwin would get a dozen or so small blisters around the keel joint each year. I opened them out and let them dry over the winter and then West Epoxyed them in the spring. This went on for maybe 3 seasons and then I stripped the area down to gel coat and put on Interlux 2000. Not one blister in the last 4 or 5 years.