Any reliance on a fuel on a boat means the range on engine
is limited by the amount of fuel you can carry, whether that is diesel, biodiesel, or methanol for fuel cells
An electric engine
with a large enough battery bank is very viable for day/weekend/short trip cruising, where the engine is primarily used for running in/out of marinas
and in case of emergencies. The amount of boats that are retrofitting electric engines to replace diesels is increasing, demonstrating that the technology has reached a price
level where there is an interest.
For long distance cruising, it becomes a trickier proposition, and for the NWP even more so, and thus generator
is Required to provide power for the electric engine to extend the range beyond the storage
capacity of the battery bank.
For those that commented on needing to have reliable instant power in case of emergency
, this is an area where electric engines outperform combustion engines of equal power.