Simple cycle gas turbines have efficiencies of 30-35%, whereas a large diesel engine can reach ~50%.
A combination of gas turbine, steam boiler running off GT exhaust and a steam turbine can reach efficiencies of ~55%. However, the system is complex and expensive, and not well suited for driving ship's propellers. Once additional kit like gearboxes are introduced, the drive system efficiency is no better than a direct-drive low speed diesel.
Finally, the diesel engines burn viscous, high-sulfur fuel... not really sure if a GT could handle the crap those engines use.
A combination of gas turbine, steam boiler running off GT exhaust and a steam turbine can reach efficiencies of ~55%. However, the system is complex and expensive, and not well suited for driving ship's propellers. Once additional kit like gearboxes are introduced, the drive system efficiency is no better than a direct-drive low speed diesel.
Finally, the diesel engines burn viscous, high-sulfur fuel... not really sure if a GT could handle the crap those engines use.