Abstract: In an exemplary embodiment, a marine powertrain includes a flywheel motor generator (MG) directly driven by an engine to which a marine drive is also connected. The MG provides a 36 volt AC power output to charge a 36 volt battery to crank the engine for starting. The marine drive is connected to the engine output shaft through a hollow rotor of the MG. The 36 volt battery may be used directly to power 36 volt loads. Auxiliary 12 volt DC and 110 or 220 volt AC outputs may be provided. The motor generator can also provide sufficient electric power to support an electrically-driven hydraulic system capable of providing for power steering, trim and other auxiliary hydraulic functions. A selective cylinder deactivation system will allow the engine to operate in a more efficient mode for electric power generation and low power propulsion than with all the cylinders operating.