You need to know what is on there now--is it an ablative paint?--rubs off easily. If so, then go with another ablative. If it is an epoxy--then you can go with either an epoxy or ablative.
Trinidad SR (epoxy)- Ultima SR (Petit--Ablative). Micron series, depending on where you are. I am redoing my 18 footer (Century)--and using Petit Ultima SR, because I occasionally trailer it, and I had an ablative on before.