Other than being a reference to a Frenchman, how Johnny Franswar (John France-O, Jean-François), joined into the song "Boney" is a matter of speculation; perhaps from sailors who were familiar with the traditional Breton "Jean-François of Nantes," or from French shipmates, or onshore.

In some versions of "Jean-François of Nantes," he is compared with a landsman, "un terrien." This may be the source of Boney being compared with a terrier in one version of "Boney."

As CET says, the memory of Bonaparte lingered. Gale Huntington reproduced several songs about him from old journals in "Songs the Whalemen Sang," 1964 (reprints inc. Mystic Seaport). None is related to "Boney" or "Jean-François."