As far as I know (not a terrific lot) during the later days of sail a Shantyman was not paid for being a Shantyman at all, just as a regular hand. And to add to that, there may well have been several leaders of shanties sung, as it doesnt make any sense to me to have a so called Shantyman sitting in the maintruck while half a dozen men 'stow a bunt' while several more work at the pumps and a few more are hauling in the fore sheets. Or did each job have to wait til the 'Nightingale' had finished the previous one ?
The next question to ask will be "What key were shanties sung in?" or maybe "Did they do requests?" :-)