On Wed, 08 Jul 2009 08:33:05 -0400, wrote:

On Wed, 08 Jul 2009 19:22:34 +0700, Bruce In Bangkok
wrote:

On Tue, 07 Jul 2009 13:02:30 -0500, Rick Morel
wrote:

On Mon, 06 Jul 2009 23:11:05 -0400, Wayne.B
wrote:
Much snipped

I would consider a 4-cycle outboard if the Perkins died, but we have
too much overhang, plus the dinghy/davits would have to go. Here goes
another discussion maybe... If the Perkins dies, I plan on replacing
it with a DC electric motor and diesel generator. The motor would
probably mostly be run from the house bank for short periods and
calmer conditions.

Your preliminary comments are correct :-)

I'm interested in your reasoning for the electric drive as it seems to
present no advantages to have a diesel fueled generator which charge a
set of batteries to provide power to an electric motor to turn a
propeller.

Given that any mechanical or electrical device will have some losses
it would seem that there will be less efficiency then a system that
connects the diesel engine directly to the propeller rather then going
all round Robin Hood's barn, as it were.



Diesel/Electric has been used on trains for a very long time. There
must be some advantages. I guess one would be full power available at
low speeds, and another would be the elimination of need for a
transmission.

Also for quite a few ships, but I believe that for trains and ships
(and some large earth moving equipment) the advantage is the
possibility of all wheel drive on wheeled equipment and the ability to
use multiple, thus smaller, generators paralleled as required, for
more economical fuel use and of course easier maneuvering as the
motors are instantly reversible. Trains too had the advantage that it
was impossible to stall the propulsion motor when starting.

But on a small boat or low power installation - remember the guy is
replacing a 40 HP diesel - I just can't see the advantage of the added
complexity.

Which is why I was asking the question.

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

On Wed, 08 Jul 2009 19:22:34 +0700, Bruce In Bangkok
wrote:

Your preliminary comments are correct :-)

I'm interested in your reasoning for the electric drive as it seems to
present no advantages to have a diesel fueled generator which charge a
set of batteries to provide power to an electric motor to turn a
propeller.

Given that any mechanical or electrical device will have some losses
it would seem that there will be less efficiency then a system that
connects the diesel engine directly to the propeller rather then going
all round Robin Hood's barn, as it were.

Cheers,

Bruce

Be glad to explain my reasoning. First, you are correct in that is is
less efficient, maybe by as much as 15%. Don't forget though, that the
clutch is going to give some losses, more so with a hydralic one.

But. In my case at least I think overall it would be better. Not a
major thing, but it would give me a bit more of stowage space because
the generator would be moved back from where the engine is and the
electric motor would take little room and be back where the clutch is
now.

I've built a couple electric cars, bikes and trikes and a motorcycle
so I'm quite familiar with the beast :-)

The electric on battery only would give 3.5 to 4 kts for several
hours, assuming I don't add any batteries. It would be used mostly for
less than an hour at a time, probably more like a few minutes to 15 or
20 minutes. The solar/wind should be able to put this back in a day or
two or three in most cases. If not, there's the generator. Assuming
the generator is not needed, a plus is no heat to make its way into
the cabin. Efficiency is really not a factor. You might as well say
it's infinity percent or totally free sine the solar/wind is
eventually putting it all back.

For longer runs, which do happen occasionally, the electric motor
would be run directly off the generator, like a train diesel
locomotive or hybrid car. This would give 5 to 6 kts, depending on
generator size, for as long as there's fuel. This mode would be where
the efficiency loss comes into play, but I feel it would be worth it
for the other battery mode. Again, this would be a fairly small part
of "normal" operation.

So there would be two motor circuits - one for pure battery and one
for generator. The pure battery would be simple, just inexpensive
"continuous duty solenoids" and maybe a couple big diodes for a
"rectactor" controller to series/parellel the batteries for 2 speeds.
You don't really need a "throttle" type controller for these lower
powers.

The generator ciruit would be simpler and cheaper as well. Instead of
a complex DC controller, SCR's can be used on the AC output, then
rectifiers to convert to pulsating DC for a true variable "throttle".

The trick is to match the prop to the motor. It would probably be
better to gear down to turn the prop slower. This could be a fairly
simple chain or notched belt drive.

So...

Mode 1, battery only, would be simple to use. No warming up the
engine, moving, cooling down and stopping the engine. Just flip a
switch and go. Most of the time the energy gets put back "free".

Mode 2, generator only, would be pretty much like now except burning a
little more fuel. Maybe. Maybe not. There are factors that could make
that up. Clutch efficiency on a "straight engine drive" and the higher
torque of an electic motor come to mind. Okay, there's got to be some
loss overall, but again I think it would be worth it having Mode 1.

The above is my opinion based on the calculations. It would work for
my cruising style, but maybe not for yours.

Rick

On Wed, 08 Jul 2009 09:31:42 -0400, Wayne.B
wrote:

If you are using it for an hour a day is it still necessary to do the
daily water test and discard the first gallon? Does it have a UV
sterilizer to kill viruses, etc. ?

Maybe I wasn't clear on that "first gallon". It's not discarded, it's
used to "flush" the sal****er out of the system. Worth it to keep the
membrane happy! The first 5 minutes is discarded, as per instructions.
This can (notice CAN) contain byproducts of bacterial decomposition
small enough to make it through, such as Hydrogen Sulfide, the "rotten
egg" smell stuff. It won't really hurt you, but yuck. That's a good
"proof" of the value of the flush. Don't flush, just turn off, then
the next day sniff the first water coming out.

Yes, the water should be tested after that 5-minute discard, mainly
because a cracked membrane will let stuff though. I occasionally use a
TDS meter, but usually just put the hose in a cup for a bit and have a
drink. The "taste test" is recommended over TDS meter by the
manufacturer. I guess if one is a bit on the overcautious side one
could use the meter first.

No UV steriizer. I feel that's a waste of power. All viruses,
bacteria, cysts, etc. are supposed to be unable to pass through the
membrane. I've been flamed before about this, but the fact remains
that we've drunk literally thousands of gallons of RO water with no
ill effects. Now I do chlorinate the water in the tanks occasionally.
BTW, chlorine and oil will quickly DESTROY the membrane. That's why I
use that jug for collecting the flush water.

Rick

On Wed, 08 Jul 2009 10:05:13 -0400, wrote:

I wouldn't be so quick to make that call, Wayne. Those advantages
might be big ones for a displacement hulled boat, especially if you
supplement the diesel with PV and wind generation charging a battery
bank.

We need somewhere between 150 and 200 horsepower to run at about hull
speed. That's a *lot* of kilowatts, PV or otherwise. I don't
believe there have been any successful implementations of
diesel-electric on mid-sized full displacement yachts. Nordhavn was
supposedly going to offer it as an option on their passage makers but
dropped the project because of costs.

http://lists.samurai.com/pipermail/passagemaking-under-power/2008-February/004081.html

or

http://tinyurl.com/nd39po

Incidently that's the same John Marshall that used to be the head of
North Sails and also managed a few America's Cup campaigns. He's a
trawler owner now, currently cruising Glacier Bay, Alaska.

On Wed, 08 Jul 2009 10:49:46 -0400, wrote:

There is a world of difference between your needs and those of a
sailboat, Wayne. I believe you know that, and just forgot for a
moment. G

Depends on the size and weight of the sailboat. A 70,000 pound
sailboat needs almost as much power at hull speed. Power
requirements for full displacement boats depend mostly on weight but
prismatic coefficient does enter into it somewhat. The biggest
cruising sailboat I've ever been on was about 120 feet. Don't know
the weight but probably several hundred thousand pounds. It had a
pair of aux diesels bigger than mine in a full walk in engine room,
everything spotless.

On Wed, 08 Jul 2009 09:22:39 -0400, Wayne.B
wrote:

On Wed, 08 Jul 2009 08:33:05 -0400, wrote:

Diesel/Electric has been used on trains for a very long time. There
must be some advantages. I guess one would be full power available at
low speeds, and another would be the elimination of need for a
transmission.

Correct on both points, those are the only real advantages, much more
applicable to trains than boats.

Ahem. Perhaps neither of you are aware of the progress being made in
seawater batteries.
Seawater is usually not available to power trains, but vessels at sea
are a different matter.
This link may discuss "state of the art" or there might be more recent
news on this exciting front in the battle for free locomotion.

http://blog.modernmechanix.com/2009/...-on-sea-water/

--Vic

On Wed, 08 Jul 2009 09:09:30 -0500, Rick Morel
wrote:

On Wed, 08 Jul 2009 19:22:34 +0700, Bruce In Bangkok
wrote:

Your preliminary comments are correct :-)

I'm interested in your reasoning for the electric drive as it seems to
present no advantages to have a diesel fueled generator which charge a
set of batteries to provide power to an electric motor to turn a
propeller.

Given that any mechanical or electrical device will have some losses
it would seem that there will be less efficiency then a system that
connects the diesel engine directly to the propeller rather then going
all round Robin Hood's barn, as it were.

Cheers,

Bruce

Be glad to explain my reasoning. First, you are correct in that is is
less efficient, maybe by as much as 15%. Don't forget though, that the
clutch is going to give some losses, more so with a hydralic one.

But. In my case at least I think overall it would be better. Not a
major thing, but it would give me a bit more of stowage space because
the generator would be moved back from where the engine is and the
electric motor would take little room and be back where the clutch is
now.

I've built a couple electric cars, bikes and trikes and a motorcycle
so I'm quite familiar with the beast :-)

The electric on battery only would give 3.5 to 4 kts for several
hours, assuming I don't add any batteries. It would be used mostly for
less than an hour at a time, probably more like a few minutes to 15 or
20 minutes. The solar/wind should be able to put this back in a day or
two or three in most cases. If not, there's the generator. Assuming
the generator is not needed, a plus is no heat to make its way into
the cabin. Efficiency is really not a factor. You might as well say
it's infinity percent or totally free sine the solar/wind is
eventually putting it all back.

For longer runs, which do happen occasionally, the electric motor
would be run directly off the generator, like a train diesel
locomotive or hybrid car. This would give 5 to 6 kts, depending on
generator size, for as long as there's fuel. This mode would be where
the efficiency loss comes into play, but I feel it would be worth it
for the other battery mode. Again, this would be a fairly small part
of "normal" operation.

So there would be two motor circuits - one for pure battery and one
for generator. The pure battery would be simple, just inexpensive
"continuous duty solenoids" and maybe a couple big diodes for a
"rectactor" controller to series/parellel the batteries for 2 speeds.
You don't really need a "throttle" type controller for these lower
powers.

The generator ciruit would be simpler and cheaper as well. Instead of
a complex DC controller, SCR's can be used on the AC output, then
rectifiers to convert to pulsating DC for a true variable "throttle".

The trick is to match the prop to the motor. It would probably be
better to gear down to turn the prop slower. This could be a fairly
simple chain or notched belt drive.

So...

Mode 1, battery only, would be simple to use. No warming up the
engine, moving, cooling down and stopping the engine. Just flip a
switch and go. Most of the time the energy gets put back "free".

Mode 2, generator only, would be pretty much like now except burning a
little more fuel. Maybe. Maybe not. There are factors that could make
that up. Clutch efficiency on a "straight engine drive" and the higher
torque of an electic motor come to mind. Okay, there's got to be some
loss overall, but again I think it would be worth it having Mode 1.

The above is my opinion based on the calculations. It would work for
my cruising style, but maybe not for yours.

Rick


I can see what you are doing but I still don't see an advantage - this
is not to say that "I wanna do it that way" is not a valid reason. But
it seems to me:

I don't know what sort of electric motor you plan on using but the one
boat installation I saw used raw water cooled motors. There was a
fairly extensive cooling system with at least one over temp warning
system per motor. The one or two water cooled generators I have seen
exhibited severe corrosion in only a few years of use. will water
cooled motors have the same service life and a low speed, small,
diesel engine?

I wonder about the high power/low power control systems. What is the
advantage of this? with the diesel auxiliary I might use idle to back
out of a slip or to creep up on the anchor rode but that is generally
a very small percent of the engine's operating time. In addition,
especially inside a marina, I have frequently seen a need for almost
full power in maneuvering, particularly when the current is running 3
or 4 knts through the marina.

It seems to me that saving space is the biggest advantage of a
diesel-electric drive. You do get rid of the gearbox but do you need a
speed change between the motor and the propeller?

In short, is there a distinct advantage in the diesel-electric drive?

I'm not trying to start an argument here, I know what the advantages
are for a diesel-electric drilling rig, for example, and I'm trying to
figure out if there is one for a small engined sailing boat.

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

On Wed, 08 Jul 2009 20:28:18 -0500, Vic Smith
wrote:

On Wed, 08 Jul 2009 09:22:39 -0400, Wayne.B
wrote:

On Wed, 08 Jul 2009 08:33:05 -0400, wrote:

Diesel/Electric has been used on trains for a very long time. There
must be some advantages. I guess one would be full power available at
low speeds, and another would be the elimination of need for a
transmission.

Correct on both points, those are the only real advantages, much more
applicable to trains than boats.

Ahem. Perhaps neither of you are aware of the progress being made in
seawater batteries.
Seawater is usually not available to power trains, but vessels at sea
are a different matter.
This link may discuss "state of the art" or there might be more recent
news on this exciting front in the battle for free locomotion.

http://blog.modernmechanix.com/2009/...-on-sea-water/

--Vic

The marvels of electrolyses. You can do the same thing with a lemon, a
galvanized screw and a piece of copper wire.

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

On Thu, 09 Jul 2009 20:14:54 +0700, Bruce In Bangkok
wrote:

The marvels of electrolyses. You can do the same thing with a lemon, a
galvanized screw and a piece of copper wire.

Yes, it is easy to make a battery out of a lemon. It's not a very
good battery however. That's because it was designed to be a lemon,
not a battery, same problem with a sea water battery. It's
interesting to see guys working on things like that, and every once in
a while something useful comes out of it.

On Thu, 09 Jul 2009 19:13:59 +0700, Bruce In Bangkok
wrote:

I can see what you are doing but I still don't see an advantage - this
is not to say that "I wanna do it that way" is not a valid reason. But
it seems to me:

I don't know what sort of electric motor you plan on using but the one
boat installation I saw used raw water cooled motors. There was a
fairly extensive cooling system with at least one over temp warning
system per motor. The one or two water cooled generators I have seen
exhibited severe corrosion in only a few years of use. will water
cooled motors have the same service life and a low speed, small,
diesel engine?

Yes, I guess "I wanna do it that way" is a valid reason. Hadn't
thought about it, but that is part of it.

The plan is to use a fork lift raise/lower motor. This is the exact
same motor as used in electric cars, but with a much heavier case. It
will develop 35 HP at 120 VDC and about 8 HP at 24 VDC. No need for
water cooling. Oh, a extra plus is the motor, like all DC motors, will
work in "reverse" as a generator under sail.

Not sure what you mean about the severe corrosion you've seen in water
cooled generators. I've seen a bunch of marine generators over 30
years old still running and looking good.


I wonder about the high power/low power control systems. What is the
advantage of this? with the diesel auxiliary I might use idle to back
out of a slip or to creep up on the anchor rode but that is generally
a very small percent of the engine's operating time. In addition,
especially inside a marina, I have frequently seen a need for almost
full power in maneuvering, particularly when the current is running 3
or 4 knts through the marina.

First, with those kinds of currents you mention it would definitely be
a situation to use the high power mode!! :-)

Low power mode would not be like idle. It would be closer to the way
it seems some manufacturers, particularly Hunter, put small engines
in, like a 10 HP diesel in a Hunter 33 a friend had. Or, if you
prefer, it would be like a max range power setting. Remember we're
talking 3.5 to 4 kts on battery only. A couple more batteries and it
could be 4.5 to 5 kts, probably with about the same "range" with the
added Amp Hours. Remember, battery only is for short time use. Max
range would probably be 4 to 8 miles, but you really wouldn't want to
do that because you'd have to use the generator to recharge. Better to
go into high power mode.


Okay, let's look at how low power, battery only, would be used. As I
had mentioned, right now we're at a marina in Slidell, LA due to a
care-giver situation. It's about 2 miles to the lake. We could use
battery only to get to the lake, sail about, etc., then maybe low
power back. In a way it does make sense because when we get back we'll
plug in and recharge "free" (fixed rate electricity).

If we moved to a nearby marina, our trip to the lake would be about
1/4 mile. Now this would make more sense to use low power. Someone not
cruising, day sailing or overnight weekending, in this situation could
use electric only and recharge when they got back. There'd be no need
for anything else unless they take occasional cruises.


Our normal sailing mode is cruising and anchoring out, with occasional
marina stays. There are times when we travel some in canals, so the
high power generator mode is needed. IOW, there are times when we need
to play motorboat for hours, days or maybe even weeks at a time.

Low power battery mode:

Yes, we know how to drop and weigh anchor under sail, but sometimes
there's little or no margin for error. Easier and safer to douse the
sails and flip a switch. Getting in and out of "port" when needed for
supplies, clearing in/out, etc. Ever try to creep though reefs
visually under sail?

Rather than go on, just look back how you use your engine. If it's say
less than a 1/2 hour a day if cruising or less than an hour
day-sailing, pure electric would work for you. Think about how nice it
would be to flip a switch and have instant power for whatever reason.
Maybe the winds are light and you want to come about and your boat is
one of those that's reluctant or very slow to do so in light
conditions. Hard over, flip the switch, come about, flip the switch
off.

The 110 VAC generator gives another plus of power for A/C if you want
to burn the fuel, fast charging with a large charger, etc. Heck, I
might pull the propane stove and put in an electric one. I wonder how
that would compare to "cooking with gas", fuel and cost wise?

It seems to me that saving space is the biggest advantage of a
diesel-electric drive. You do get rid of the gearbox but do you need a
speed change between the motor and the propeller?

As I had mentioned, it would take a recduction for much better
propellor efficiency. A chain drive would be cheapest, but a bit
noisy. Notched belt would be much ore expensive, but quiet. One could
maybe find a "gearbox" surplus or junked or... The motor brushes can
be electricly swapped for reverse.


In short, is there a distinct advantage in the diesel-electric drive?

I don't think there is a "distinct" advantage and in some cases a
disadvantage. It depends on one's boating style. Our case I feel there
is an advantage. Wayne had mentioned his trawler - in his case I would
say big disadvantage. As mentioned before, I've had lots of experience
with electric power and with "green" power - solar and wind. Whenever
you use those you have to look at your needs and wants and decide if
it's for you. You can't just turn on stuff or jump into your electric
car and drive it like a combustion one. You have to do a bit of
"resouce management". Most folks want "energy on demand" and are
unwilling to put up with the "work" to use or the waiting sometimes.


I'm not trying to start an argument here, I know what the advantages
are for a diesel-electric drilling rig, for example, and I'm trying to
figure out if there is one for a small engined sailing boat.

No argumant, Bruce :-) I know where you're coming from. It's a complex
subject with all kinds of "gotcha's". I wish it were like in the
movies, where they have a 2 X 2 ft. solar panel on a 20 passenger
electric transport and it runs it at 90 MPH all day and even all night
(from starlight???). It just doesn't work that way in the real world.

Other than a dinghy, I wouldn't even consider an electric power boat.
Well, maybe a slow 'African Queen' type on a lake or bayou for short
weekend use.

Rick