HIERARCHY LEVEL IN DECK DEPARTMENT

As mentioned earlier, the crew on ship is divided mainly into two departments ; the Deck and Engine department.The deck department is concerned with the watch keeping on the bridge and maintenance and repair of ship's cargo gear,accommodation and also the ships lifesaving equipment.
Getting confused with all the various rank and their duties is quite easy. So in order to understand ranks in the deck department and their job a little better, here is a lowdown of the ship’s deck department.
Captain: The highest authority on the ship, the rank of the captain is the most responsible on the vessel. All the key operations and decisions have to be taken with the consent and knowledge of the captain.
Chief Officer: The Chief Officer, or Chief Mate as he is often called, is second in position to the Captain. He is in charge of the deck department and also the deck crew. He oversees all the cargo operations including its handling and stability. He is also responsible for training the deck crew in safety and rescue operations besides other emergency procedures.
Second Officer: Second Officer or second mate is responsible for all the navigation jobs and holds his rank below the Chief Mate. A second mate has the responsibility of maintaining the charts and also plots the routes for navigation. Although
on various oil tankers a second mate may assist the chief officer for tank cleaning and maintenance as well.
Third Officer: A rank below the Second mate, a Third Mate may not be present on all ships, although all big vessels generally do have this rank on board. The third mate is mainly responsible for all the safety related operations onboard which include regular maintenance of all the firefighting equipment and lifeboats.
Deck Cadet: A deck cadet is more of a nautical science graduate or trainee who Hierarchy Level in Deck Department works directly under the chief mate on the ship. Normally a deck cadet has to complete one full year of training on board under the senior ranks before he can apply for examination/promotion.

Boatswain: A Boatswain, pronounced as Bosun, is in charge of all the deck crew and he supervises the crew on board. Working in association with the chief mate, a bosun plans the tasks for the crew and oversees the work given.
Deck Fitter: A deck fitter is responsible for hot work and repairing/ fitting operations required and works under the chief officer.
Able Seaman: ABs, as they are fondly called, are the members of the deck department who keep watches along with the officers on the bridge. While sailing, the job of an AB is to carry out navigational duties on bridge, like maintaining the course and standing as a lookout during night watch.
Ordinary Seaman: The ordinary seaman, or the OS, is the lower rank on the deck side and is responsible for variety of duties on the deck. An OS is often required to wash and sweep the deck besides doing various deck side jobs like painting, scaling and buffing.
Trainee OS: He is a fresher in the deck department who works as a trainee and performs all the work required for an ordinary seaman.