The history of whaling is pretty well documented Q, and Stuart is one of the best authorities on the topic. The first British and American whalers entered the Pacific in 1787, primarily working the Brazil Banks, and other grounds close to the West Coast of South America. Whalers didn't begin calling at the Hawaiian Islands until 1819. So the song can't have existed before then. According to Starbuck's History of the American Whale Fishery (1877 [1989]), whalers began working the northwest coast of N. America 1835, got up around Kamchatka to begin the bowhead fishery in 1843, and in 1848, Captain Royce of the bark Superior, out of Sag Harbor, N.Y., was the first to work a season North of the Bering Straits. Royce wrote that since they were the first to whales on those grounds, the whales were comparatively tame and easy to strike. So I think 1848 as the very earliest possible date for the song is right. I think the conventional wisdom on "Old Maui" has always been that it dates to the 1850s, but no one has done a definitive study. I myself might take that up when I turn my dissertation into a book, but that's still a couple of years off.