I learned the verse in question from Geoff Kaufmann, who probably got his version from Stan. It's pretty much the same as Mark cites in the second post of this thread, except that one sings "wahine" instead of "island girl" or "island maid" in the last line. Based on my own research of whalers journals, they certainly were familiar with the word "wahine," quite intimately in fact, but the term "island maid" turns up pretty frequently too, so I think it's a matter of taste. I have never seen the verse in question in any whalers' journals, and am inclined to think that if Hugill didn't write it himself, it was unique to the singer from whom he got the song. As for the tune, it is also unclear if Stan wrote it, but he (almost) definitely originated that tune in folk circles.
Geoff always mispronounced the word "kanaka," singing "KAN-aka." I got a lot of weird looks when I sang it that way the first time I was in Hawai'i. It should be pronounced "ka-NA-ka," which means "person" or "human being" and which was the common Euro-American name for Pacific Islanders, Hawaiians in particular. The posters above are absolutely correct that kanaka seamen were common aboard whalers as well as other trading vessels, etc. The kanakas that Dana writes about were working in the California hide trade, and he basically says they were the finest human beings he had ever "fell in with." The word kanaka, was apparently used as a slur in the early 20th century, but in recent years has been rehabilitated. It's most common usage today is the Hawaiian term "Kanaka maoli" which means a "full-blooded" Native Hawaiian.