I first encountered this song (before the Kingston Trio's first record came out) in Carl Sandburg's The American Songbag, first published in 1927 and, fortunately, reprinted and currently available.

In the thread George linked to above, Joe Offer posted the words as they appear in The American Songbag   HERE:

That's the way I learned it from Sandburg's book (complete with a sort or Calypso beat). I heard it on a recording of Calypso songs shortly thereafter and I had the rhythm right. Then, the Kingston Trio's recording of it came out.   Shortly thereafter, while I was singing in a local coffeehouse, someone requested "The Sloop John B." and I sang it the way I'd been singing it for three or four years. He griped that I didn't sing it right. "Didn't sing it right?" I said. "What do you mean?" "You didn't sing it like the Kingston Trio," he responded. As if the Kingston Trio were some kind of authorities on folk music. I had to educate him as to the background of the song, and suggensted that the KT probably got from the same source I did (and among other things, I pointed out that there were three of them and only one of me).

Don Firth