: Switches between a smaller turbine for efficiency and a larger one for speed. 4. Why the Change?
Because gas turbines are most efficient near maximum power, modern ships use "Combined" (CO) configurations to balance speed and fuel: The Naval Gas Turbine Ship Propulsion Dynamics ...
By the 1960s, navies needed higher —more speed and weaponry in smaller, lighter ships. : Switches between a smaller turbine for efficiency