If the boat is made of polyester resin and glass cloth, you can use either polyester resin or epoxy. If it's made of epoxy and glass cloth, you can use epoxy, but not polyester resin. The reason is polyester resin doesn't cure correctly on epoxy.

In the interest of simplicity, if it's poly based fiberglass and you don't have polyester resin, just use epoxy, it'll work fine.