Special Duty Officer (Merchant Marine). An officer of the Naval Reserve.
Third Mate - The junior Officer of the ship is usually the safety Officer. Third Mate is also responsible for firefighting equipment, lifeboats and emergency systems and is in charge of a (bridge or cargo) watch.
Master Mariner - Possesses all the qualifications to command a ship. Candidates must be proficient in the application of a barometer, chronometer and sextant to map a course across the open ocean waters.
Chief Mate - Head the deck department on a merchant vessel and serve as second in command. Primary responsibilities are the vessel's cargo operations, its stability and supervising the deck crew. Second Mate - Be in charge of navigation and responsible for maintaining the charts and navigational equipment on the bridge. Duties also entail developing the voyage plans under the direction of the Ship's Master.