<P> Since USS Theodore Roosevelt, the aircraft carriers were manufactured in modular construction . This means that whole sections could be welded together with plumbing and electrical equipment already fitted, improving efficiency . Using gantry cranes, the modules were lifted into the dry dock and welded . In the case of the bow section, these can weigh over 1,500,000 pounds (680 t). This method was originally developed by Ingalls Shipbuilding and increases the rate of work because much of the fitting out does not have to be carried out within the confines of the already finished hull . </P> <P> The total cost of construction for each ship was around $4.5 billion . </P> <P> All ships of the class are powered by two A4W nuclear reactors, housed in separate compartments . They power four propeller shafts and can produce a maximum speed of over 30 knots (56 km / h) and maximum power of 260,000 bhp (190 MW). The reactors produce heat through nuclear fission which heats water . This is then passed through four turbines which are shared by the two reactors . The turbines power the four bronze propellers, each with a diameter of 25 feet (7.6 m) and a weight of 66,000 pounds (30 t). Behind these are the two rudders which are 29 feet (8.8 m) high and 22 feet (6.7 m) long, and each weigh 110,000 pounds (50 metric tons). </P> <P> The Nimitz - class ships constructed since USS Ronald Reagan also have bulbous bows in order to improve speed and fuel efficiency by reducing wave - making resistance . As a result of the use of nuclear power, the ships are capable of operating continuously for over 20 years without refueling and are predicted to have a service life of over 50 years . </P>

How big is the rudder on an aircraft carrier