Paint coming off in sheets means it hasn't adhered to the underlying substrate. It's either a case of not thoroughly cleaning off the gunk on the old paint and sanding it or the paints are incompatible. Has nothing to do with the boat being in freshwater. Funny, when I was researching Micron paints, learned right quick that Micron 66 could not be in fresh water. Wasn't something that Interlux was trying to hide. Very important to know as our marina has a freshwater upwelling that leaves a couple of feet of fresh/brackish water on top of the salt water.