Burning diesel to make electricity then storing it, then converting back to electricity, then turning an electric motor to turn a propeller. Straight diesel propulsion is far more simplistic and efficient. Now for ac and other lighting loads a small genny being run with computer controlled load management and large battery bank makes sense. Genny runs at optimal load and all excess load is stored. Batteries are full genny shuts down until batteries are discharged to predetermined point. Wash, rinse repeat. On a site I needed power 24/7 for tenant. Load was between 50 and 80 amps 240 v. Light load for bigger diesel gennys and burned 1 gal an hr. Year round. Designed a great inverter system using victron and lithium batteries with genny. Already to build system and covid hit, supplier couldn't fly his tech in to install. Bang head on wall. It was going to be great system.