Future frigates need to reduce fuel consumption and emissions, while improving effectiveness. This paper quantitatively compares top speed, fuel consumption, emissions, acceleration performance and engine loading of hybrid diesel-electric and gas-turbine-electric propulsion, using validated models and introducing sequential turbocharging and power take-off. This simulation study demonstrates hybrid diesel-electric propulsion can reduce fuel consumption and CO2 emissions by 10% to 25% compared to gas-turbine-electric propulsion, while reducing top speed by 3 kts. Moreover, hybrid diesel-electric propulsion is found to provide good acceleration without thermally overloading the engine when speed control is employed for the electric drive in combination with torque control for the diesel engine.@en