Marine Engineers are the officers of a ship which operate and maintain the propulsion and electrical generation systems onboard a ship. They also can help with the design, build, and repair of these complicated systems. New design is mostly included within the naval architecture or ship design. The merchant and military fleets of the world would not move without Marine Engineers. The field is closely related to mechanical engineering, although the modern engineer requires knowledge (and hands on experience) with electrical, electronic, pneumatic, hydraulic, chemistry, control engineering, naval architecture, process engineering,gas turbines and even nuclear technology on military vessels.