The engine department on a US flagged merchant ship is an extremely important department. It is responsible for all maintenance and operation of the electrical and mechanical equipment. Besides the engines in the engine room, the engine department crew is responsible for all of the sewage, air conditioning, lighting, and water on the ship. Without the engine department, the ship would not move, nor would it be very pleasant to be on.
A wiper is the entry level position in the engine department. The name came from the job function on old-fashioned ships, with a wiper actually wiping the equipment off, as well as watching and learning from the more experienced members of the engine department. Today the wiper is more like a "gofer," helping and assisting everyone else in the department.
After serving as a wiper, a mariner can work his way up to becoming an oiler; responsible for making sure the ship equipment is properly oiled. Other unlicensed positions include electrician, machinist, and refrigeration technician. All of these jobs are considered to be QMED positions, standing for Qualified Member of the Engine Department. When someone has mastered all of the QMED responsibilities, he is a Junior Engineer — the highest unlicensed position available in the engine department.
A first assistant engineer, second assistant engineer, and third assistant engineer are all licensed positions, with these engineers having passed a Coast Guard test to become licensed. Before a mariner can sit for a test for any of these licensed positions, she must have completed a certain amount of time at sea.
A first assistant engineer (referred to in some countries as the second engineer) is the chief engineer's right-hand man (or woman). She reports directly to the chief engineer and is responsible for the main engines, refrigeration systems, and any other equipment in the engine department that has not been assigned to a Second, Third, or Fourth Assistant Engineer.
Often referred to simply as "Chief," the Chief Engineer is the head of the engine department on a US Merchant Ship, and holds a great deal of responsibility. He is in charge of the entire department, and is responsible for supervising all the mechanical and electrical equipment on board the ship. The Chief Engineer reports directly to the Captain of the ship.