The Master /captain is responsible for the safe and efficient operation of the ship including its seaworthiness, safety and security, cargo operations, navigation, crew management, and legal compliance and for the persons and cargo on board.
The Chief Officer /Mate is the second in command of the vessel, is often equated, in corporate terms, to a senior manager for the operations on board, as the Mate is in charge of a number of departmental functions. In modern cargo vessels, the Mate holds appointments like Head of Deck Department.
The 2nd Officer / Second Mate is the third in command (or on some ocean liners fourth) and a watchkeeping officer, customarily the ship's navigator.
The Navigator's role focuses on creating the ship's passage plans. A passage plan is a comprehensive, step by step description of how the voyage is to proceed from berth to berth or one port to another. The plan includes undocking, departure, the en route portion of a voyage, approach, and mooring at the destination.
Chief Engineer is the senior most engine officer of an engine department on a ship, typically a merchant ship, and holds overall leadership and the responsibility of that department. As a person who holds one of the most senior roles on the ship, they must have excellent communication and leadership skills. They will be expected to regularly work alongside other crew members and external consultants, and most importantly, provide guidance to his or her team.