When I served, (British merchant Navy 1960s)we occassionally bunkered Royal Navy ships and RFA supply ships ( Merchant Navy crewed Fleet Auxilaries)and we were told by crew mwmbers of both that shantying was NOT permitted on board "White Ensign craft".
Re "Drunken sailor" I was told by Bert Grey, (who had served in square riggers and schooners out of the Baltic in the 1930s) who acted as shantyman for our ship where a lot of work was done by "Norwegian steam" (man power) that in Merchant ships it was regarded as a "show off" piece for the shantyman, the first and last verse were as standard but the rest were improvised, on the spot by him referring to incidents on the voyage and painting scurrilous pictures of members of the crew and their personal habits, and the more bawdy and vulgar the better!!!He also said it was Devilishly hard to do well!!