The other comment I would make about Dana's observations is that he doesn't use the term "sea shanty/chantey/chanty" but simply says "sailor's songs" or "work songs." Apparently the term hadn't been invented yet. Dana's observations are among the earliest which focus on these songs we love to sing; it's a true pity that no one has run across his private manuscript of lyrics and tunes. Maybe I'll recreate one and make my millions!
I bet one of the scholars mentioned above knows where Dana's private papers are held. Or is this another case of "Who would want this mouldy old sea chest full of papers? Toss it out!"