On Sun, 28 Sep 2008 17:01:32 +0000, Larry wrote:
... It is producing 6,500
watts of 220VAC 50Hz serious electrical power, 24/7 for about a litre
per hour. ...

6500 W / 746 W/HP = 8.7 HP at [say] 0.5 lb per HP hr = 4.3 lb/hr
If a US gal of gasoline weighs about 6.5 lb (it varies) that would be
over half a gallon an hour.

Still, a useful tip...

Brian W

Brian Whatcott wrote in
:

Still, a useful tip...



It's time the boats went diesel-electric. Sure works great for the
trains...(c;

On Tue, 30 Sep 2008 20:05:12 +0000, Larry wrote:

Brian Whatcott wrote in
:

Still, a useful tip...



It's time the boats went diesel-electric. Sure works great for the
trains...(c;

How about direct drive as used by the WWII German torpedo boats? You
stop the engine and restart it turning the other way. They didn't have
a compressor and only had enough air to start the engines once. Put a
premium on seamanship to say the least. All the biggest ships, tankers
and boxboats both, are that way. They avoid having a multimillion buck
gearbox. As for diesel-electric, all the Holland-America cruise ships
have it. One of the ones I was on had five engines for two shafts.
That way you can overhaul one and run on four easily. I saw them
loading cylinder heads at the start of a trip. All their ships have a
bar directly above the wheelhouse, with floor to ceiling glass on all
three outside walls. Great in a Norwegian or Alaskan fjord, or in a
harbor.

Casady

"Richard Casady" wrote in message
...
On Tue, 30 Sep 2008 20:05:12 +0000, Larry wrote:

Brian Whatcott wrote in
m:

Still, a useful tip...



It's time the boats went diesel-electric. Sure works great for the
trains...(c;

How about direct drive as used by the WWII German torpedo boats? You
stop the engine and restart it turning the other way. They didn't have
a compressor and only had enough air to start the engines once. Put a
premium on seamanship to say the least. All the biggest ships, tankers
and boxboats both, are that way. They avoid having a multimillion buck
gearbox.

'Multi-million gearbox'?
Have you ever looked at an engine that will turn a big ships propeller at
80-100 rpm with direct drive?
They do not come cheap.

On Wed, 1 Oct 2008 11:31:27 +0200, "Edgar"
wrote:


"Richard Casady" wrote in message
.. .
On Tue, 30 Sep 2008 20:05:12 +0000, Larry wrote:

Brian Whatcott wrote in
:

Still, a useful tip...



It's time the boats went diesel-electric. Sure works great for the
trains...(c;

How about direct drive as used by the WWII German torpedo boats? You
stop the engine and restart it turning the other way. They didn't have
a compressor and only had enough air to start the engines once. Put a
premium on seamanship to say the least. All the biggest ships, tankers
and boxboats both, are that way. They avoid having a multimillion buck
gearbox.

'Multi-million gearbox'?
Have you ever looked at an engine that will turn a big ships propeller at
80-100 rpm with direct drive?
They do not come cheap.


It seems to be more a matter of size as the BIG engines are all low
RPM engines that at lower RPM while lower power engines are usually
higher speed engines. for example, the Emma Mursk uses a 108,920 H.P.
@ 102 RPM engine and probably doesn't require a reduction gear, while
a smaller ship might use a 5,800 Hp @ 600 RPM engine with reduction
gear.

Bruce-in-Bangkok
(correct Address is bpaige125atgmaildotcom)

Bruce in Bangkok wrote in
:

It seems to be more a matter of size as the BIG engines are all low
RPM engines that at lower RPM while lower power engines are usually
higher speed engines. for example, the Emma Mursk uses a 108,920 H.P.
@ 102 RPM engine and probably doesn't require a reduction gear, while
a smaller ship might use a 5,800 Hp @ 600 RPM engine with reduction
gear.

Bruce-in-Bangkok
(correct Address is bpaige125atgmaildotcom)



I've stood atop the 7-cylinder, 2-stroke beast that powers SeaLand
"Performance". It's 38,800hp at 102 RPM and burns 75 tons of heavy oil
boiled in the exhaust stack before injection to thin it at about 76 RPM,
her econocruise speed give or take the load, of course. The massive
flange aft of the engine is directly coupled with huge bolts to the
screwshaft going out to her single screw. If you were standing on a
platform at the base of a blade, you could extend your hand about
halfway up that blade towards the hub. I can't remember how many blades
were in the picture, sorry.

The engine is computer controlled so noone has to sit and baby sit it in
the air conditioned control room where the massive power panel is also
located for the large array of 3-phase 408?V diesel gensets power that
are located in a compartment under the main shaft under the rudder gear.
The day I was there they were about half loaded for sea and the panel
said they were generating a little more than half a megawatt to keep the
fruit cool and the frozen food frozen in the freezer containers. They
got plenty of AC power!

If the computer sees something it doesn't like on an array of engine
sensors in each cylinder, it pages the duty engineer wherever he may be
to come look. If something really bad were to happen, the computer
would shut her down to prevent further damage and all hell would break
loose.

Captain Larry, a ham friend of mine, is one of her two masters and he
says he never gets tired of playing with her...(c; Forward or reverse
she will run either way, being two stroke with no valves. Big blowers
ventilate her when the ports are open at BDC before the next 5 foot trip
up the cylinder, injection and explosion drives her down again. Oh how
I wanted to go to sea with them to see it run and hear that thumping for
myself.

Captain Larry claims he can do an emergency stop from econocruise speed
in NEARLY 2.5 MILES!....which is also about her "turning circle" in flat
water. Not bad considering she's 980' long. Standing on the bridge, I
commented, "Well, at least you won't get hurt in a front end collision.
Hell, you're half a mile back from the accident!" A color TV system
let's you watch for those damned crab pots over the bow, but I doubt
they worry over them like we do....(c;

Air start....either way. Very exciting.

On Wed, 1 Oct 2008 11:31:27 +0200, "Edgar"
wrote:

Have you ever looked at an engine that will turn a big ships propeller at
80-100 rpm with direct drive?
They do not come cheap.

It is a universal, applying to all sizes, that the transmission costs
a much as an engine. All the biggest engines have long been direct
drive. As for price, the big marine engines are cheaper per horse than
the smaller ones. By the way, gears suck up power. So does electric
drive. The family runabout, a jet boat, has no transmission. In fifty
years, I never missed it even once.

Casady

On Wed, 1 Oct 2008 11:31:27 +0200, "Edgar"
wrote:

Have you ever looked at an engine that will turn a big ships propeller at
80-100 rpm with direct drive?
They do not come cheap.

It is a universal, applying to all sizes, that the transmission costs
a much as an engine. All the biggest engines have long been direct
drive. As for price, the big marine engines are cheaper per horse than
the smaller ones. By the way, gears suck up power. So does electric
drive. The family runabout, a jet boat, has no transmission. In fifty
years, I never missed it even once.

Casady

(Richard Casady) wrote in
:

How about direct drive as used by the WWII German torpedo boats? You
stop the engine and restart it turning the other way. They didn't have
a compressor and only had enough air to start the engines once. Put a
premium on seamanship to say the least. All the biggest ships, tankers
and boxboats both, are that way. They avoid having a multimillion buck
gearbox. As for diesel-electric, all the Holland-America cruise ships
have it. One of the ones I was on had five engines for two shafts.
That way you can overhaul one and run on four easily. I saw them
loading cylinder heads at the start of a trip. All their ships have a
bar directly above the wheelhouse, with floor to ceiling glass on all
three outside walls. Great in a Norwegian or Alaskan fjord, or in a
harbor.

Casady



My concept for diesel-electric stems from the boaters' tremendous need
for electrical power for an ever-increasing array of electrical gadgets
far exceeding low voltage DC's ability to provide it. This need exceeds
the need for propulsion 95% of the time, the propulsion only used to get
in and out of the dock in real sailboats. So, it simply makes sense to
remove the 5%-used, directly coupled propulsion engine that doesn't
provide real electrical power and replace it with a real genset that
does. Now having real electrical power aboard, high voltage AC to match
real loads, it's simply a matter of providing the driveshaft solid-state
speed controlled, high voltage AC traction motors, just like trains have
been using for decades, to drive the boat in and out that other 5% of
use.

It simply makes better sense.....

To make machinery noise much more tolerable to the inhabitants, we must
do away with the high revolution prime movers of this electrical system
and, instead, use very primative, very slow turning diesels, which have
a very long history of amazingly long MTBF (mean time between failures),
very low maintenance (just change the oil a couple of times a month for
24 hour service), with a minimal number of moving parts (Listeroids have
12). Now disconnected from the drive shaft and its constant alignment
problems, engines and alternators can be put on a horizontal, not
slanted, subframe with intensive use of soft rubber mounts between the
engines and the frame and the frame and the boat. This is exactly why
the interior diesel and mechanical noises heard by passengers of a
Mercedes Benz diesel sedan are so low. There are two levels of dampers
between the body and the engine and one layer of dampers between the
body and the suspension system. Add soft mounting to extensive sound
absorbing materials, with tight controls on penetration of the
materials, and you have a very quiet diesel power plant anyone can live
with except, of course, the sailing hermits, who are not a major part of
the customers.

A lot of the propulsion noise you hear in a boat is transmitted by rigid
engine mounts to keep it aligned which are marginal dampers and through
the shaft to hull bearings, themselves. Diesel-electric eliminates
both.

On Wed, 01 Oct 2008 10:27:40 +0000, Larry wrote:

Now disconnected from the drive shaft and its constant alignment
problems,

Family runabout has a tubular driveshaft with a U-joint. Never had any
problems with alignment. A 59 Turbocraft, the tenth jet boat ever sold
in the US.

Casady