On Aug 1, 4:44 am, "Marc" wrote:
....
My main objectives are :
- having a backup engine with which she should at least run 4 kn without
having the need for double propellors (too much drag it's a fast sailing
yacht nog an moto sailor ;-)
....

Well, I don't want to get into the my boat is faster than... ALL
sailboats are slow. Still, I do have a cruising boat with top speeds
right around twenty knots under sail and it has two engines and two
props. It also has two rudders, two dagger boards and two hulls...
An interesting side effect of having two propulsion engines is that
the props are sized to WOT with both engines running and are thus
"over propped" when only one motor is running. I think this is good
since it means that I can run one engine slowly and still have it
loaded up when motoring through a calm. I don't have a pyrometer on
the engines and they are too small for commercially available flow
meters so I can't really claim to know if the theory really works, but
I run on the assumption that it does... Anyway, it might be fun to
explore the differences in installed cost of twins vs a single and bow
thruster. I think it would be easier to get home on one twin than on
one bow thruster . Another possibility would be to put in a
continuous duty drop down style bow thruster on an "Z" drive. Your
genset could then run that as a "get me into the dock now that I've
sailed home" engine.

-- Tom.

The 60' LWL motor yacht of our design launched last summer has a
conventional 200 HP 6-cyl diesel (it's a purely displacement boat and
doesn't need 200 HP except in emergencies ). If I were starting on it
today I'd certainly take a hard look at the Siemens ELFA boxes with
the idea of installing 2 smaller engines and using only one of them
most of the time. That way the engine(s) would operate at higher load
and be happier.

Dunno why you'd want to do that in a sailboat, though.

Cheers,
Micael Porter

"Marc" wrote:

I am building a 60 foot aluminum sailyacht and considering using diesel
electric propulsion with 2 identical diesel enigins of 70 - 100 hp. The
builder is not very experienced in ths field so I am doing some fieldwork
myself .

Anyone with experience in diesel eletric solutions in this size for sailing
yachts?

Cheers.

Marc




--
Posted via a free Usenet account from http://www.teranews.com

On Wed, 01 Aug 2007 21:00:52 -0400, Wayne.B
wrote:

On Wed, 1 Aug 2007 16:44:41 +0200, "Marc" wrote:

Roger & Bruce; thanks for your reaction. Pioneering is nice.. but not at any
price ;-) Not my main reason for looking into this...

My main objectives are :
- having a backup engine with which she should at least run 4 kn without
having the need for double propellors (too much drag it's a fast sailing
yacht nog an moto sailor ;-)
- not needing a seperate generator by using one of the main engines as a
generator
- less noise / vibration?

Consider putting a folding or feathering prop on the "wing" engine to
minimize drag. Mount two large alternators on each engine (200+amps),
and use them to drive a large battery bank and redundant inverters.
That will be much cheaper to build and service than a diesel electric
system, and will give you full backup for everything. Many long range
cruising trawlers are being built that way.

You are talking about a 60 ft. sail boat. right?

Generally sail boats have auxiliary engines for those times that the
wind doesn't blow. There are also motor-sailers with somewhat bigger
engines but they really don;t go much faster.

I'm assuming that you will have a modern fin keel, broad beam, shallow
hull depth, type of boat with minimum skin friction. I did a really
quick calculation, assuming 20,000 lbs. displacement and came up with
45 shaft H.P., Shaft RPM of 1100 and a speed of about hull speed.

Now, that is probably a bit underpowered as you will be going "up
hill" sometimes but say you add another 25 - 30% and you still aren't
talking about a very big engine.

You've already decided on a sail boat so you have one source of power
and a secondary, the auxiliary diesel. Now do a little research. Go
down to the commercial docks and see how many commercial boats, guys
that spend their whole lives on the water, have more then one source
of moving the boat. The world's fishing fleet is probably 99% single
diesel engine powered and if you've ever been on the Grand Banks in
the winter time that alone should convince you that a second engine is
not really vital to life and happiness.

Lastly, if you are like most owners of 60 ft. bespoken yachts you are
not in the first blush of youthfulness so either you have a crew or a
really strong wife or you are going to need powered winches. So you
have to figure on a gen-set that runs much of the time, if only to
operate the autopilot.

So there you go. A sixty ft. mast and enough dacron to build a circus
tent, a 75-100 H.P. auxiliary engine and a generator set.

And round the world you go =:-)


Bruce in Bangkok
(brucepaigeATgmailDOTcom)

On Thu, 02 Aug 2007 18:16:04 +0700, wrote:

So there you go. A sixty ft. mast and enough dacron to build a circus
tent, a 75-100 H.P. auxiliary engine and a generator set.

My point was that if you put a couple of *big* alternators on each
engine you don't really need a generator, and what would have been the
generator engine can now drive an off center shaft with a folding
prop. That way you can have it all more or less. If you want super
reliability, it is also necessary to have seperate fuel tanks for each
engine with appropriate transfer and filtration plumbing, along with
seperate batteries, etc.

Your engine sizing estimates do not take windage into account which
can be considerable on a 60 footer trying to motor into a 30 or 40 kt
headwind. And yes, sometimes it is necessary. I also take some issue
with your comparison to single engined commercial boats. Those boats
almost always have spacious engine rooms with room to work, lots of
essential tools and spares, and someone aboard who knows how to get
the job done. That is not the case with most 60 foot sailboats that
I've seen.

On Aug 1, 7:15 am, "Marc" wrote:
I am building a 60 foot aluminum sailyacht and considering using diesel
electric propulsion with 2 identical diesel enigins of 70 - 100 hp. The
builder is not very experienced in ths field so I am doing some fieldwork
myself .

Anyone with experience in diesel eletric solutions in this size for sailing
yachts?

Cheers.

Marc

http://www.avanteyachts.com/joomla/i...at_port792.jpg

Joe

On Aug 1, 5:15 am, "Marc" wrote:

I am building a 60 foot aluminum sailyacht and considering using diesel
electric propulsion

Marc

Got to agree with Roger Long. On the other hand ya could go down to
your local rail yard and find the guy who works on locmotives.
Think.............. EMD

Electric Motor Division

Bob

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

On Thu, 02 Aug 2007 10:40:27 -0400, Wayne.B
wrote:

On Thu, 02 Aug 2007 18:16:04 +0700, wrote:

So there you go. A sixty ft. mast and enough dacron to build a circus
tent, a 75-100 H.P. auxiliary engine and a generator set.

My point was that if you put a couple of *big* alternators on each
engine you don't really need a generator, and what would have been the
generator engine can now drive an off center shaft with a folding
prop. That way you can have it all more or less. If you want super
reliability, it is also necessary to have seperate fuel tanks for each
engine with appropriate transfer and filtration plumbing, along with
seperate batteries, etc.

Not to start a war, but I still don;t understand why you want sails
and two motors...

Your engine sizing estimates do not take windage into account which
can be considerable on a 60 footer trying to motor into a 30 or 40 kt
headwind. And yes, sometimes it is necessary. I also take some issue
with your comparison to single engined commercial boats. Those boats
almost always have spacious engine rooms with room to work, lots of
essential tools and spares, and someone aboard who knows how to get
the job done. That is not the case with most 60 foot sailboats that
I've seen.


Well, I did admit that it was a quick and dirty calculation. But, if
you have 30 - 40 Kts of wind you've got super sailing weather for a 60
ft. boat.

You are right about engine rooms but I'm not so sure about people who
know how to get the work done. Example: The average Thai fishing boat,
say 50 - 60 ft. that makes voyages to Indonesia or Bangladesh to poach
fish usually had a Thai Captain, maybe a Thai 1st Mate, and the rest
of the crew are Burmese who are hired for probably less then $100 a
month. I'm not so sure about their expertise.

But, you have hit the nail on the head -- there are vast quantities of
people driving around in boats that don't know a thing about the
hardware. The neighbor boat to me had some people working on it, I
asked the Owner what was doing and he told me he was having the engine
oil and filters changed. A nice guy but didn't know where the oil
filter was.


Bruce in Bangkok
(brucepaigeATgmailDOTcom)

On Fri, 03 Aug 2007 08:45:38 +0700, wrote:

Not to start a war, but I still don;t understand why you want sails
and two motors...

Well, they weren't my specs but I can understand the motivation.

Let's start with the premise that a boat needs aux propulsion for
various good reasons - entering harbors; short handed sailing with one
or two people; lack of wind; wind in wrong direction; schedules to
meet; broken furling gear; etc. These things all occur in real life
as opposed to the "ideal".

Let's additionally assume that a modern 60 foot boat also needs a
generator to provide power for air conditioning, refrigeration,
freezers, emergency battery charging, entertainment equipment,
microwave oven, etc. So that's one way of getting to two engines that
most folks on a well appointed 60 footer would not argue with.

Now that you've got two engines, how do you provide backup
functionality if one breaks down? Hence my suggestion for heavy duty
alternators on each allowing them to do double duty as power
generators and back each other up in that role. In addition, I would
also equip the second engine with an off center shaft and
folding/feathering prop which allows it to serve as back up to the
primary aux engine.

Modern boats with modern conveniences have a lot of complexity, and
the more redundancy the better in my experience. My own cruising boat
these days is a trawler with all the back up systems I can manage -
twin engines, twin generators, multiple battery banks, and multiple
charging sources. The idea being to eliminate as many single points
of failure as possible, be able to cruise in the boondocks with
confidence, and to keep the boat going until we can reach a suitable
repair facility.

So far the strategy has paid off. In three years of ownership and
10,000 miles of cruising we have experienced two unscheduled shutdowns
of main engines and numerous generator issues, none of which were show
stoppers because of the backup systems on the boat.

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)