As was mentioned earlier, a lot depends on the details. Did this vessel "sink" in fresh water or ocean water? How far down, for how long?
As far as how much it will cost to repaint her, well, that depends too. If you use
AwlGrip or IMRON, it won't be cheap. For instance Imron costs at least $250 a gallon.
Here is a quote from another site:
"I worked for Hatteras in New Bern, where the BIG ones are built, in the late 70's. All hulls are sprayed with Imron over gelcoat. Imron is a 2 part polyurethane enamel that is very hard, durable, and when properly applied, produces an extremely high gloss finish. It should only be applied by spraying because it is so thin. A Binks Model 18 will do an excellent job. The key is to lightly fog first, let that tack 5-10 minutes, then apply to about 10 mils thick. No runs, no drips, no errors! "
Good luck!