John, A few years ago, we had a few DUPONT people working on epoxies that applied to Trim Parts and other idiotic ways to stick things on cars. They discovered long ago that two things KILL epoxy real quick, sunlight and heat. Here at this PAINT SHOP we also have learned that no matter how much ULTRAVIOLET INHIBITOR is included in the base prime or the basecoat ( which has very little),or the Clearcoat( which should have an awful lot), ultraviolet light will penetrate all the way to the substrate, which in your case is the Epoxy on the deck. If any polyesters are used over epoxy that can and will in time cause a problem. I dont believe you used any polyester products over the epoxy but that information could help someone in the future. In short, your boat is painted that beautiful deep blue that does nothing but attract ultraviolet light, and create heat( CALLED HOT)!! Your boat has done a little sun time already and that could have caused some of the problem. I'm not sure what products you have used on BIG BLUE, but some batches of IMRON have been known to be lacking in the INHIBITOR DEPT. Amazingly enough, we have also discovered ( by accident) that the color of your filler ( microballons or high density filler) will have a effect on if it moves around or not! EXAMPLE: Light colored fillers work better than dark colored fillers. Crazy but true. My fingers are getting tired , call me John!!