Did you like "The Sand Pebbles" ?In Shaw's "Pygmalion" "Professor Henry Higgins" remarks that there must have been many regional dialects that he could identify , " Even down to the street " so there must have many different ones amongst the crew of the Titanic.
I found this to be true in the USN in my first experience in "Boot Camp". In the "Boot Camp Company" were there many - from the "youse guys" from the North-East to the "y'all's" of those from the South.....and several others.
Another "Navy Movie Gripe" is a scene from the movie "The Caine Mutiny.". A crew member is delivering a message to Captain Queeg and is rather sloppy looking in his uniform. The Captain remarks about this. But in real life in the USN that conduct would have never been tolerated in the first place. This one scene (perhaps the only one ! LOL ) in which I am in agreement with the Captain's remarks. LOL.
You always tried to look your best when you were in the presence of the Captain. Just another incidence of how Hollywood portrayed the ordinary sailor. The Division Officer or Petty Officer would never have permitted a member of his Division looking like that.
From personal experience I was the Senior Petty Officer in charge during the end of my enlistment. I never would have sent one my men to the Captain looking like that !
On the accents of the Titanic's crew, for a bit of fun compare Charles Lightoller's actual voice (from the recording of his 1930s BBC broadcast) to that of the actors who played him in the 52', 58 and 97' films. Night and day ! Lightoller was known for his good sense of humour and would probably have found it funny.