I have a new-last-year fiberglass boat with a white hull. I keep it in
the water for the boating season, but it spent the winter shrink-wrapped
ashore at a marina.

The marina called today to ask if I wanted them to paint the bottom
black. (As if that were the obvious choice.) Maybe a stupid question:
Does the bottom paint color matter for protection, or is the choice of
color just an appearance thing?