Chanteyranger,

The scanty amount of info *directly* about both these songs, *combined* with inferences I would make, inadequate as it may be, suggest to me that both songs came about in the second half of the 19th century in America —without being any more specific.

If we want to go strictly by direct sources, we can say that Eckstorm/Smyth (1927) is the earliest for something really confirmed as what we call "John Kanaka." But that's not really helpful. To my mind, these are not static songs as we know best from folk revival performances but must be connected to other similar songs to see their evolution. For "Cape Cod Girls," I'm honestly not even sure what that is. How are we to actually distinguish it from "Bound for [South] Australia" songs? I have to include the latter songs if I'm trying to "date" "Cape Cod Girls" because the distinction between the two is, I think, only the construct or happenstance of some popular publication.

But yes, floating verses. I'm not even convinced they are floating verses -- which suggests something even more fixed than I think they are. I didn't even think to compare these songs so, again, I have to think the person asking the question might have been exposed to some rendition based in some publication that happened to have incidental verses of one and incidental verses of the other these happened to share the same tropes.

I'm not suggesting that verses we encounter in chanties never have any connection to the songs, but I'd say maybe less than 50% did until the folk revival froze book versions in Carbonite.

My theory on "John Kanaka" is that it is based in the minstrel song "Ol' Aunt Jemima" OR ELSE both are based in the same prototype. There's nothing remotely Hawaiian about its core. There isn't even enough evidence to confirm it said "Kanaka" at all, never mind that the "kanaka" is a Hawaiian one. Yet even allowing that a surface trait in this development of the song was that it had Kanaka, that's very peripheral to what makes up the song.

People won't be surprised now to hear me say I strongly suspect "South Australia/Cape Cod Girls" is also based in a minstrel song. (Think "Alabama" or "South Virginia" rather than "Australia", and rhyme "born" with "corn," rather than Cape Horn. "Bound for South Australia" is in the style of an American popular song [minstrel] is I've ever heard one.)   

Sorry to shoot in various directions, but it's my way of saying that these two songs are two dishes coming from the same kitchen, for all intents and purposes, about the same time. One is the pork chop with corn, mashed potatoes and gravy and the other is the steak with corn, mashed potatoes, and gravy—though sometimes the cooks substitute broccoli or French fries.