Thanks for the help Bat Goddess, that's cleared that up! Didn't realise it was such a recent song (reference to "pulling on a whaling crew" made me think it was older). Still, I guess if it's written in a 'traditional' style then it'll sound that way regardless.
Spose I'll have to dig out some books about Navy lingo if I'm going to do any more like that. A quick search on Google for Cyril Tawny comes up with a fair selection of books and CDs.