Words interest me, so I looked up chantey in an older Oxford English Dictionary and only found shanty, with a date of 1869 and a reference to Chambers Journal. A OED supplement does have chantey, and attributes the first printed usage to Nordhoff, Nine Years a Sailor, 1856. It would be interesting to know when these words were first used in those forms, and why the English dictionaries prefer shanty and the American Webster prefers chantey. It seems to me that 1856-1869 is late for the words to have come into English (all sources attrib. to the French). No importance but good trivia.