With regards to the deck officers ranks on the Lusitania why did they have a junior and senior 3rd officer?did they have junior and senior 2nd officers and first officers?How come they did not have 1s,t 2nd to 6th like with the white star line?
The senior officers had more responsibility.
Their uniforms had distinctive sleeve lace to indicate rank, similar to that of the Royal Navy.
On the sleeve of the service dress coat, the master (who was the captain) wore four "rings" on the sleeve and on the "shoulder boards" wore four braids. The Chief Officer wore three rings, similar to what a "full commander" in the Navy would wear. First Officer wore the two rings of a lieutenant in the Royal Navy and the U.S.Navy (a LT in the U.S.Navy is sometimes referred to a as "full lieutenant" as opposed to a lieutenant-junior grade).
Most of the deck officers of the RMS Titanic and presumably the RMS Carpathia and RMS Lusitania also held commissioned ranks in the Royal Navy Reserve.