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What Is the Job Description of a Merchant Mariner?

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Merchant mariners work long hours in a hostile environment and spend up to eight months at a time away from home, but earn between $68.09 and $800 a day. They are civilian sailors who serve as the officers and crew aboard civilian and non-combatant, government-owned ships. Their duties at sea range from navigation and operating a ship’s engines, to electronics, communications and providing food for a ship’s crew.

Deck Department Officers

A ship's deck department consists of the licensed deck officers and the unlicensed-but-documented seamen who engage in navigation and general maintenance. Licensed officers include the master and the mates. The master has the overall responsibility for a voyage. First mates serve as a ship’s cargo officer. Second mates are navigation officers and third mates attend to the safe navigation when they are on duty. All mates are in charge of a “navigational watch,” the shift on which they work and oversee fuel and liquid cargo transfers.

Deck Department - Unlicensed

Merchant mariners in the deck department are either ordinary seamen or able seamen. They assist the officers in a ship’s navigation, and steer ships as directed by the watch officer. The deck supervisor, who makes daily work assignments for unlicensed personnel is the boatswain -- pronounced "bosun." Duties include cleaning and painting the areas of the ship outside the engine department. They also set up and secure the lines that moor the ship to wharfs and piers.

Engine Department Officers

A chief engineer is the licensed merchant mariner in charge of the engine department. The department is responsible for the operation and maintenance of a ship’s engines, generators and electrical systems, plumbing, fuel systems and liquid cargo transfers. Licensed officers in the engine department include first, second and third assistant engineers. During their individual watches, they supervise the unlicensed engine department personnel.

Engine Department - Unlicensed

Depending on the type of ship, qualified members of the engine department may include electricians and refrigeration technicians, doing the same work they do ashore. Oilers and junior engineers assist with plumbing repairs, generator-engine oil changes and general maintenance in the engine department. Deck engine mechanics maintain lifeboats and rescue vessels. Fireman-watertenders control the flow of fuel and pumpmen assist in transferring fuel into a ship’s fuel tanks and loading and unloading liquid cargoes.

Steward Department

Not all ships have a steward department. On large vessels, a chief steward is in charge of the steward department. The chief steward orders foodstuffs and cleaning supplies, and prepares the midday and evening meals. A night cook or baker prepares breakfast and the midnight meal. Galley hands assist both the steward and the night cook in food preparation and storage, cleaning the galley and doing laundry. Shrinking crews -- ships under 4,000 gross register tons have as few as four crew members -- have shifted the burden for these hotel-type services to the unlicensed deck personnel.


Will Charpentier is a writer who specializes in boating and maritime subjects. A retired ship captain, Charpentier holds a doctorate in applied ocean science and engineering. He is also a certified marine technician and the author of a popular text on writing local history.

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