This confuses me. A hybrid is an internal combustion engine (in this case diesel) powering a generator to drive electric motors. How can this be more efficient than direct drive from the diesel engines to the propellers. There is a large loss of efficiency in the generation of electric power in the generators and further loss of energy in the electric motors that power the propellers. Oddly hybrid power works in cars. The engine runs at its perfect efficient rpm and charges a battery and then on to the electric motors. It works because a car is driven in many different modes of speed and stop and go. A ferry is nominally a constant speed device until docking and departure.
Nope direct drive is not more efficient not with modern electric motors and rectifier / inverters.
Having huge diesels ramping up and down load following also burns a lot of extra fuel as the BSFC map clearly will show a peak efficiency zone for any given engine it is near the 75% full load point and mid range rpm. Running an engine away from that point means lost combustion products , soot, unburnt hydrocarbons , NOx if you go lean burn. Running smaller generators at their peak BSFC point is always going to be more efficient than running a single large engine ramping up and down with loads. You can also shut down some or all of your smaller gensets and run off the pack for peaks and valleys of the load point. It’s been conclusively proven that hybrids are more efficient it’s not even up for debate the hard data is just to plentiful. You can drive two identical Toyota’s one Camry is a hybrid the other is pure ICE the hybrid will be getting 20-30 mpg better mileage it really is that simple now. Toyota is not even making the nonhybrid version anymore the Camry is 100% electric drive units now. The Corolla will follow probably in 2026.
Diesel locomotives that add a small hybrid pack are getting 50% reductions in fuel burn over 250+ mile trips which is typical of a regional class loco. A single box car of LFP cells can send a 100 car locomotive 150 miles all by itself. Old timers don’t fathom how far tech has come now this is not 1960 it’s the 21st century we have suitcase sized packs that can put out 200+ kilowatts that’s 260+ hp more than enough to push any consumer sized vehicle to illegal speeds in under 10 seconds. The link for the ultra caps above show 8kg worth is 500+ horsepower on tap. This is the 21st century.