Thank you kindly for that. Much appreciated.
I should have worded my original post much better - I was wondering more about what a Staff Captain and a Marine Superintendent's jobs involved in they heyday of the ocean liners.
I believe that "staff captains" are more modern invention, at least when it comes to the Titanic era--I am unsure about the late ocean liner period from the late 1930's and onward. As I recall, despite the Staff Captains responsibility in 'commanding' the hospitality crew, he or she also has a masters license, and is typically the person who would take command of a vessel should the ship captain become disabled (the position is sometimes called
vice captain on some cruise lines). Because of this, if we were to compare the modern staff captain to the crew of Titanic, a modern staff captain would have some of the combined responsibilities of Titanic's Chief Officer Wilde and Chief Purser McElroy (who was also responsible for Titanic's stewards and victualizing staff).
Staff captains did not exist, as far as I know, in 1912. At least not on White Star vessels. However, someone who is more familiar with the history of staff captains might be able to give you a better answer.
Unfortunately, I have
no idea about the role Marine Superintendent's play in today's merchant navy, so I cannot offer you any insights on what they might have done during the hey day of the ocean liner.