Like some of the more recent posts, a buddy that has sailed all his life has told me that wet sanding is the way to go. Not wishing to mix electricity and water, I'm considering a straight line, air sander, as used in body shops. Add a convenient pipette hooked to a hose to dribble water onto the pad and it's all good!
I *do* like the idea of the drywall sanding pad, too; as I have a couple to hand.
My bottom paint is pretty good. I just hafta get rid of he barnacle "glue" and rough the surface for the next coat.