It's a bit of a mystery. On the mooring the prevailing winds are SW, so this would have been the NE exposure. The other 2 hulls are holding up just fine on the same side (both sides) and it is only an issue on one hull side (starboard). In winter, the sun is lower and my boat sits lower on it's stands than neighboring boats, so the topsides would be mostly in shadow, and the problem was fairly even in its distribution along the entire side. By removing the underlying gelcoat with 80 grit to where the gelcoat is transparent on the matt, we're basically starting over on that whole side according to the AwlGrip Specification: HullGard Extra, then High Build Primer, then Awlcraft 2000 to match. The end result should be a sound finish that looks good for 7+ years (or whatever the life of the Awlcraft 2000 is).