Re: Best sander for bottom sanding?
I'd say since he's just brazing VC-17 (which is very hard paint), he should be looking for metal paper... 3m sells paper with a "sticky" backing, I've been using, but I'm taking off ablative, so it's probably not the paper for you... I've yet to have paper slip though. Purple grade I am using, I think they make some for automotive that'll do the trick to braise VC-17 for another coat. I can't imagine you needing to take the 17 off though, just rough it up (since it's such a thin layer when applied) and it self-levels.
Hull #68 S2 7.9 on our little landlocked puddle, Lake Wallenpaupack, PA, it's cheap, trailerable, and paid for.