CODAG CODAG Combined Diesel and Gas is a marine propulsion system that combines diesel engines and gas turbines to drive the same shaft, depending on operational needs. , short for Combined Diesel and Gas, refers to a type of marine propulsion system in which both diesel engines and gas turbines are connected to a common propeller shaft via a combining gearbox. Depending on the vessel's operating profile, the diesel engines are typically used for cruising and efficient low-speed operation, while the gas turbine is engaged when higher speed or power is needed. Both power sources may be used alternately or together, depending on the system design.
This configuration provides a flexible balance between fuel efficiency and high-performance capability. CODAG systems are commonly used in naval vessels where high-speed operation may occasionally be required without sacrificing endurance or economy during patrol or transit phases. However, they are mechanically more complex than pure diesel systems and require careful integration of control systems and power management.