In all merchant ship whether its general cargo, oil tanker, OSV or cruise vessel, there are mainly three departments, Deck department and Engine department and saloon department. In deck department, crew are required to work under the supervision of officers on deck and on bridge. In Engine department, crew work under the supervision of Engineers in the Engine room. They are called GP ratings (General purpose rating). There is also third department called saloon department which comprises of cooks and a stewards.