When I was at sea in the 1960s (UK) I sailed with a Shetlander called Bert who was in his late 50s (at least)at that time and he had sailed in square riggers out of Sweden and Finland in the Baltic in the 1930s, he was our Shantyman as we did a lot of hard work in that ship by "Norwegian steam" (that is by muscle power) and he maintained that he always understood and accepted that "Drunken sailor" was a Shantymans show off piece, that is only the First verse was traditional, the rest, the Shantyman improvised around who was on deck on the day, recent events, both on board and not, and "personalities" from the ships company and on shore in that port!!!. Try it some time, it is really Thinking on your feet, and can be a lot of fun.