On Sun, 11 Nov 2007 00:57:06 -0500, Wayne.B
wrote:

On Sat, 10 Nov 2007 20:14:36 GMT, Short Wave Sportfishing
wrote:

Navistar is developing a very interesting diesel/electric hybrid lift
truck for utility companies. According to them, in tests, they are
achieving fuel reductions of 50/60% over normal lift truck operations.

It's only a matter of time until that gets to larger boats.

The strength of hybrids comes from good acceleration with a relatively
small engine. That does not compute for constant speed/constant power
applications like a boat.

I'm not at all sure about that.

I read somewhere recently that the new diesel/electric hybrid freight
train engines are so damn efficient it's scary. I think, and I can't
remember the exact figures (maybe somebody who can make Google sing
can find it please?), it was 480 tons for 30 miles on one gallon of
diesel.

Again, that's the way I remember it - it was on Discovery one evening
and I was half paying attention, but I think that's pretty close to
what they said.

And diesel/electric submarines are pretty damn efficient.

"Short Wave Sportfishing" wrote in message
...
On Sun, 11 Nov 2007 00:57:06 -0500, Wayne.B
wrote:

On Sat, 10 Nov 2007 20:14:36 GMT, Short Wave Sportfishing
wrote:

Navistar is developing a very interesting diesel/electric hybrid lift
truck for utility companies. According to them, in tests, they are
achieving fuel reductions of 50/60% over normal lift truck operations.

It's only a matter of time until that gets to larger boats.

The strength of hybrids comes from good acceleration with a relatively
small engine. That does not compute for constant speed/constant power
applications like a boat.

I'm not at all sure about that.

I read somewhere recently that the new diesel/electric hybrid freight
train engines are so damn efficient it's scary. I think, and I can't
remember the exact figures (maybe somebody who can make Google sing
can find it please?), it was 480 tons for 30 miles on one gallon of
diesel.

Again, that's the way I remember it - it was on Discovery one evening
and I was half paying attention, but I think that's pretty close to
what they said.

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.

Eisboch

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? :-)

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?

On Sun, 11 Nov 2007 21:39:44 GMT, Short Wave Sportfishing
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?

It will work but there is little or nothing to gain unless the boat
runs at a variety of different speeds and/or the engines exceed the
ability of reasonably sized mechanical transmissions. Diesel-Electric
is considerably more expensive than a mechanical transmission and is
not cost effective in boats with less than locomotive sized engines.

On Sun, 11 Nov 2007 17:14:19 -0500, Wayne.B
wrote:

On Sun, 11 Nov 2007 21:39:44 GMT, Short Wave Sportfishing
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?

It will work but there is little or nothing to gain unless the boat
runs at a variety of different speeds and/or the engines exceed the
ability of reasonably sized mechanical transmissions. Diesel-Electric
is considerably more expensive than a mechanical transmission and is
not cost effective in boats with less than locomotive sized engines.

Ok - so if Navistar can make this work for utility lift trucks with
that kind of efficiency, would they work in boats?

On Sun, 11 Nov 2007 22:37:31 GMT, Short Wave Sportfishing
wrote:

It will work but there is little or nothing to gain unless the boat
runs at a variety of different speeds and/or the engines exceed the
ability of reasonably sized mechanical transmissions. Diesel-Electric
is considerably more expensive than a mechanical transmission and is
not cost effective in boats with less than locomotive sized engines.

Ok - so if Navistar can make this work for utility lift trucks with
that kind of efficiency, would they work in boats?

I don't think so. Utlity lift trucks are constantly changing speeds,
most boats do not.

"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

On Sun, 11 Nov 2007 17:25:42 -0500, "Eisboch" wrote:


"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.

Yeah - It's slowly sinking in that it might not work.

I just hate giving up on the idea though. :)

Short Wave Sportfishing wrote:
..

I just hate giving up on the idea though. :)

I am sure you won't.