I have a '77 Seaswirl 17' that spends 8 months a year in the water. When getting it ready to put in for this year I noticed what appear to be blisters below the water line. When cleaning it in prep to waxing I also noticed pits that go thru the Gelcoat. Am I in trouble here? Has anyone had a similar problem and if so what did you do? I want to put the boat in but do not want to find it on the bottom. Thanks