"Short Wave Sportfishing" wrote in message
...
On Sun, 11 Nov 2007 15:27:20 -0500, Wayne.B
wrote:

On Sun, 11 Nov 2007 07:02:43 -0500, "Eisboch"
wrote:

And diesel/electric submarines are pretty damn efficient.

If the setup allows the diesel engine to run at a constant, optimum RPM,
regardless of vehicle speed (as diesels are really designed to do) there
will be a gain in efficiency.

Yes, and that's important on a train, it's likely having a
continuously variable transmission that allows the engine to run at an
efficient speed regardless of the actual load. On a boat running at a
more or less constant cruising speed, running at the right RPM is a
function of reduction gear ratios and prop pitch. Once you get those
two factors set correctly they will stay that way in most cases. The
one exception that comes to mind is slowing down for rough seas but
real men in real boats don't do that do they? :-)

So why wouldn't it work on a larger boat?


Like Wayne pointed out, usually on large diesel boats you run them at a
constant speed most of the time anyway, hopefully at an optimum RPM for prop
pitch, cruising speed and fuel efficiency.

I was thinking more of hybrid cars and trucks that run at varying speeds. A
small, biofuel diesel would run at a constant RPM, turning an alternator
that charges a battery bank.

Eisboch