A. I am a sailor. I work as an OS on board.
B. I am an AB I work as a sailor.
C. I am a sailor. I work as a quartermaster.
D. I am an AB I work as an oiler.

A. The captain is the head of a ship.
B. The master is the head of a ship.
C. The deck department is under the command of the chief officer.
D. The pilot is the head of a ship.