When Jeff Warner and Jeff Davis used to do school programs here in Maryland, they were asked not to sing "John Kanaka-naka" in our oh-so politically correct public school system because it was a "derogatory term referring to native Hawaiians" (which I didn't know...) So there are mines and pitfalls unless the person teaching the shanties is up on the actual meaning and history of some of the more arcane lingo being used in the songs...