Wouldn't it be more logical to say that the sailor wouldn't have worked on any ship in the south sea?
He could still know about the ships. Some of those ships might be (in)famous, with tales told throughout the land of them and their stalwart crew. Depending on the level of technology or utility magic, books or broadsheet articles may have been written about them. Or his current captain, another crewmate, the barkeep (or barfly) at his favorite tavern, or even one of his relatives may have worked on them and have told stories about them.