On Aug 1, 7:36 am, "Roger Long" wrote:
I've gone around the diesel electric question on a few research vessels
where it is a good solution.

It is going to be quite expensive.

It makes most sense when the loads while the boat is not moving are a
significant percentage of propulsion loads. This doesn't fit the ususal
cruiser profile (except maybe for Skip and Lydia

You had better have a builder who really understands it. There are going to
be some complex boxes and equipment in between the generators and the props.
Keeping them cool and dry will be a challange. The wiring will be unlike
anything most builders have seen.

It's going to take up a lot more space than a conventional propulsion plant.
There will be some effeciency losses so you will need to carry more fuel on
a boat that already is devoting extra space and weight to this enthusiasm.

When you have problems with it and pull into Pango Nowhere, it's going to
be amusing watching the locals trying to figure out how to fix it.

I love diesel electric but it would not have crossed my mind to try it in a
60 foot sailboat. If having a DE sailboat is a goal in itself because you
like to tinker and want to be a pioneer, cool. If you just want to sail and
cruise, I would forget it. You can use that space, weight, money, and
research effort much more usefully.

--
Roger Long

Fair call Roger . Only time I've seen it pulled off are for very big
anchor handling vessels and Mississippi river pushboats. With that
type of work with very very heavy loads it saves a ton of money on
reduction gears, and engine maintaince. The constant RPM is a charm,
and with all three gensets (EMD's) going they had the torque to snap
off anything.

He could save space and go small scale with some of the new Azipod
propulsors. I seem to recall someone's making a yacht size Azipod, it
would make racing around the bouys a blast.

Joe

In article om,
Joe wrote:
On Aug 1, 7:36 am, "Roger Long" wrote:
I've gone around the diesel electric question on a few research vessels
where it is a good solution.

/snip/

I love diesel electric but it would not have crossed my mind to try it in a
60 foot sailboat. If having a DE sailboat is a goal in itself because you
like to tinker and want to be a pioneer, cool. If you just want to sail and
cruise, I would forget it. You can use that space, weight, money, and
research effort much more usefully.

Fair call Roger . Only time I've seen it pulled off are for very big
anchor handling vessels and Mississippi river pushboats. With that

DE propulsion seems to be getting moderately popular in new big
catarmarans: the new Lagoon 420 uses a DE drive system, as do boats from
Africat and Broadblue (the last-named uses the Ossa powerLite drive, based
around the bady diesel from the Smart Car).

In a monohull you're more limited in the ability to keep the generator at
upper deck level, but in a 60' boat it ought to be do-able.

A quick google on "diesel electric catamaran" turned up some poterntially
helpful links. The Ossa system is described at:

http://www.ossapowerlite.com/

--
Andy Breen, not speaking on behalf of the University of Wales
"The internet, that wonderful tool for bringing us into contact
with things that make us wish we could scrub our brains out with
dental floss.." (Charlie Stross)

On Aug 1, 2:15 am, "Marc" wrote:
....
Anyone with experience in diesel eletric solutions in this size for sailing
yachts? ...


You might want to read the two part series in PBB (http://www.proboat-
digital.com/proboat/20070607/) on hybrid propulsion. They cover
engine sizing and a good deal more. It sounds like you've already
decided that you want to go with electric and I don't want to dissuade
you However, if you are just after fuel economy and are looking at a
true diesel electric system rather than an electric boat with backup
generation a variable pitch propeller will do a better job than an
electric transmission for a good deal less money.

-- Tom.

Looks like a great article. THX!

Marc

wrote in message
oups.com...
On Aug 1, 2:15 am, "Marc" wrote:
...
Anyone with experience in diesel eletric solutions in this size for
sailing
yachts? ...


You might want to read the two part series in PBB (http://www.proboat-
digital.com/proboat/20070607/) on hybrid propulsion. They cover
engine sizing and a good deal more. It sounds like you've already
decided that you want to go with electric and I don't want to dissuade
you However, if you are just after fuel economy and are looking at a
true diesel electric system rather than an electric boat with backup
generation a variable pitch propeller will do a better job than an
electric transmission for a good deal less money.

-- Tom.

On Aug 3, 5:48 am, "Marc" wrote:
Looks like a great article. THX!


You are welcome. I notice the the link I posted is broken in my
browser so if anyone else is interested they might want to go to
http://www.proboat-digital.com and look for the june/july issue.
Professional Boat Builder is an usually good rag. There were a couple
of points that I thought were interesting about the article:

1) despite the fact that Calder is somewhat famous and well connected
he obviously had trouble shaking real numbers out of the d/e folks and
in the end resorted to a good deal of hand waving and extrapolation.
We mortals may have trouble getting enough disinterested information
on small d/e setups to do any valid engineering.

2) thermodynamics version 3.0 for the new digital age (tm) as brought
to you by Solomon Technologies is still pretty much the same old stuff
we learned back in the steam age. You still have to balance the
equations and there ain't no such thing as a free lunch.

3) the inefficiencies in small boat propulsion systems are primarily
the result of propeller inefficiency at slow rpms which result in
lightly loaded engines which are inefficient producing a vicious
circle. The logical place to break the circle is at the propeller.
Attempts to break the circle at the transmission are very likely
become exercises in moving the problem around rather than fixing it.

-- Tom.

Printing the article seems impossible. Understandable.. any idea how I can
get a digital or print copy of the article?

wrote in message
oups.com...
On Aug 3, 5:48 am, "Marc" wrote:
Looks like a great article. THX!


You are welcome. I notice the the link I posted is broken in my
browser so if anyone else is interested they might want to go to
http://www.proboat-digital.com and look for the june/july issue.
Professional Boat Builder is an usually good rag. There were a couple
of points that I thought were interesting about the article:

1) despite the fact that Calder is somewhat famous and well connected
he obviously had trouble shaking real numbers out of the d/e folks and
in the end resorted to a good deal of hand waving and extrapolation.
We mortals may have trouble getting enough disinterested information
on small d/e setups to do any valid engineering.

2) thermodynamics version 3.0 for the new digital age (tm) as brought
to you by Solomon Technologies is still pretty much the same old stuff
we learned back in the steam age. You still have to balance the
equations and there ain't no such thing as a free lunch.

3) the inefficiencies in small boat propulsion systems are primarily
the result of propeller inefficiency at slow rpms which result in
lightly loaded engines which are inefficient producing a vicious
circle. The logical place to break the circle is at the propeller.
Attempts to break the circle at the transmission are very likely
become exercises in moving the problem around rather than fixing it.

-- Tom.

On Aug 3, 12:02 pm, "Marc" wrote:
Printing the article seems impossible. Understandable.. any idea how I can
get a digital or print copy of the article? ...

I'll bet PBB would sell you one ?
subject=Professional BoatBuilder). You could save each page image
(right click save image as) to someplace (eg. your desktop) and then
print them individually. You might also be able to save the web page
for off line viewing with a grabber (eg. spiderZilla)...

Good luck,

-- Tom.

wrote:
On Aug 3, 5:48 am, "Marc" wrote:
Looks like a great article. THX!


You are welcome. I notice the the link I posted is broken in my
browser so if anyone else is interested they might want to go to
http://www.proboat-digital.com and look for the june/july issue.
Professional Boat Builder is an usually good rag. There were a couple
of points that I thought were interesting about the article:

1) despite the fact that Calder is somewhat famous and well connected
he obviously had trouble shaking real numbers out of the d/e folks and
in the end resorted to a good deal of hand waving and extrapolation.
We mortals may have trouble getting enough disinterested information
on small d/e setups to do any valid engineering.

2) thermodynamics version 3.0 for the new digital age (tm) as brought
to you by Solomon Technologies is still pretty much the same old stuff
we learned back in the steam age. You still have to balance the
equations and there ain't no such thing as a free lunch.

3) the inefficiencies in small boat propulsion systems are primarily
the result of propeller inefficiency at slow rpms which result in
lightly loaded engines which are inefficient producing a vicious
circle. The logical place to break the circle is at the propeller.
Attempts to break the circle at the transmission are very likely
become exercises in moving the problem around rather than fixing it.



A nice summary. I read the 2nd article as basically saying "there
ain't no free lunch and the D/E folks are having a hard time
justifying their systems".

On a cat a SIMPLE D/E system would almost seem to work rationally
(like Glacier Bay "do away with the batteries philosophy"), but I LIKE
the redundancy of twin engines instead of a more complex
genset/motor/controller system

Evan Gatehouse

On Aug 3, 9:43 pm, Evan Gatehouse
wrote:
....
On a cat a SIMPLE D/E system would almost seem to work rationally
(like Glacier Bay "do away with the batteries philosophy"), but I LIKE
the redundancy of twin engines instead of a more complex
genset/motor/controller system
....

One of the joys of yachting for me is that it is supremely and
unapologetically irrational . I certainly don't want to discourage
folks from finding beauty in systems and practices even when they are
hard to rationalize.

Like you, I like the redundancy of twins. I can attest that it has
been comforting to know that when one engine eats the bearings on its
salt water pump and spits them all over the engine room or drops its
propeller into the depths that my boat still has propulsion.

The Ossa (Glacier Bay) system looks interesting and could drive twin
props with multiple gensets so it might be pretty durable. I have
read their tech paper (http://www.ossapowerlite.com/tech_library/
fuel_efficiency/fuel_efficiency.htm). If you take them at their word
the system might well use less fuel in typical service than an old
mechanically governed over sized diesel system with a fixed prop that
was significantly undersized for its average service would... I can
imagine a scenario where it would be an easy system to rationalize (a
large yacht with big hotel needs and big fuel bills). On the other
hand, I was a little taken aback by the argument that claimed a long
commercial history of d/e propulsion because of its inherent
efficiency and also claimed that efficiencies of their system were the
result of very recent advances in technology and their proprietary
systems. I suppose you just have to take them at their word for the
second bit as their tech paper has no sources or verifiable numbers on
efficiencies. My understanding of the history of marine diesel
electric is different from theirs. I know that for the past hundred
years or so d/e systems have been used by navies and commercially for
a number of very good reasons. Those reasons include the ability to
run under water (submarines), to operate quietly (ASW) , to provide
quick changes in power over a wide range (tugs), to provide for
multiple, remote or vectorable thrusters (platforms), to provide for
big hotel needs (cruise ships) and so on. However, I don't think it
is historically correct to put fuel efficiency, per se, in that
list. This is certainly one of those cases where I would love to be
proven wrong. The siren call of a relatively cheap technological fix
for the woes of small boat propulsion and power generation is
strong. But, caveat emptor.

-- Tom.

On Sat, 04 Aug 2007 07:43:54 GMT, Evan Gatehouse
wrote:

I LIKE
the redundancy of twin engines instead of a more complex
genset/motor/controller system

Absolutely, redundant is good, simple is good, unnecessary complexity
is not.

Trains and large ships have good engineering reasons for D/E, small
cruising boats do not. As an FYI, 60 ft *is* small.