The mold in the picture will/should clean up fine.
However a boat allowed to get to this state is a red flag to look very carefully at the rest of it.
1984 Fast/Nicholson 345 "FastForward"
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)