CODOG CODOG Combined Diesel or Gas is a marine propulsion system where either diesel engines or a gas turbine - never both simultaneously - drive the same propeller shaft. , short for Combined Diesel or Gas, refers to a naval propulsion architecture in which a ship can be powered either by diesel engines or by a gas turbine - but not both at the same time. The two power sources are connected to a shared propeller shaft through a combining gearbox, but they operate independently of one another. Diesel engines are typically used for economical cruising, while the gas turbine is engaged for high-speed operation.
The advantage of CODOG systems lies in the operational flexibility between efficiency and speed without the mechanical and thermal complexity of running both systems simultaneously. However, since the power sources cannot be combined, the maximum output is limited to the capacity of the gas turbine alone.