The three published versions of this tune I have found are closely related, but not to Lloyd's version. The Harlow tune is similar to the others, but with the opening phrase simplified. I had always thought that the tunes in the Huntington book were simply taken directly from other printed sources, there rarely being tunes found in the logbook journals, but this tune, though similar to the one in Colcord, is different enough IMHO to be classified on its own. And I don't know where it comes from.

I think Lloyd might have amended his text after seeing the Huntington book, eg the second verse in the Leviathan ("We've weathered the Horn...") has been added to the version he recorded earlier.

Roud lists a version called Captain Bunker, from Maine, printed in the Bulletin of the Folksong Society of the Northeast 6 (1933). I do not have access to that; it would be interesting to see it. The same article also reprints a text from J. Ross Browne, Etchings of a Whaling Cruise (1846). This certainly has textual similarity to Coast of Peru, with the line, "Lay me on Captain Bunker, I'm hell for a long dart," yet the chorus recalls The Diamond, "So be cheery, my lads! Let your hearts never fail, while the bold harpooneer is a striking of the whale."

But I can cast no light at all on Lloyd's source for his tune (sung much more slowly and freely on his first recording, BTW, than on Leviathan).