Can't help with this ,but the thread reminds me that Cliff Hall of the Spinners always claimed shanties were West Indian in origin. His explanation (possibly a wind-up to annoy the shanty purists) was that the WI fishermen had temporary shelters (shanties) on the beach where they gutted their fish (and no doubt smoked some wacky woodbines) which were on rollers made of tree trunks. When a storm was threatened they hauled them up into the trees for safety from tidal waves etc., singing the type of song we associate with capstan work on ships.[and, of course, the Spinners used to sing "Sally Racket" among other shanties so this thrtead hasn't crept too far!]