RCE wrote:
I understand the use of diesel electric in locomotives - the electric motor
drives have immense amounts of torque. But what's the advantage in a boat
or car?


Until they get the bugs worked out of lobe-type engines
(similar to the Wankel), the diesel gives the most bang for
the buck *if* it can be kept within a fairly narrow power band.

Using a diesel to drive a car or truck suffers because it
has to put out varying amounts of torque, up to full rating,
at widely varying RPMs. Even so it can get better fuel
economy than a gasoline engine in the same service.

If you couple a diesel to a generator, so it can constantly
run at it's most efficient RPM & throttle setting, then use
the electricity to drive the car, you basically have a
locomotive only with tires for road use. Adding tricks like
high-density permanent magnet motors (or the still-expesnive
cobalt motors) & advanced tech battery banks & regenerative
braking & solar panels & bulk/trickle chargers boosts the
efficienct higher yet, but basically it's still a
constant-load diesel with an electric transmission.

Regards
Doug King