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Old 30-11-2016, 14:10   #511
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Re: Oceanvolt Hybrid Motor

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Originally Posted by StuM View Post
I presume this abundance of electrical energy is because of your large diesel generator?
And the enormous battery bank...
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Originally Posted by Octopus View Post
... one of the great advantages of of a diesel-electric propulsion system, which is the abundance of electrical power that helps to improve the cruiser's quality of life. True, with conventional propulsion you can have this too by installing a powerful genset and a big battery bank, but these are at additional cost, weight and complexity, whereas for diesel-electric these come as standard.
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Old 30-11-2016, 18:01   #512
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Re: Oceanvolt Hybrid Motor

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Originally Posted by myocean View Post
--------
Every electric motor can operate with maximum torque over the whole range up to the speed where the maximum power is reached - not further! In this example at 700 rpm max power is .
---------
Attachment 137227


That is a broad and inaccurate statement.

You may want to look at the different capabilities of series, shunt, compound, induction, synchronous, universal and stepper motors.
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Old 30-11-2016, 19:49   #513
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Re: Oceanvolt Hybrid Motor

Is this still going on? I'd forgotten...

Anyways at the time when this was all blowing up,I was so interested and excited about the hype.
Solomon,Regenautics,OSSA,Fast Electric Yacht Systems,and Siemens. I talked to them all. On the phone. and emailed.

After asking for video proof-Floscan with GPS at a few varying speeds for a few seconds each,then doing a u turn and doing the same (to account for currents) speeds and consumption....they all crapped out. Wouldn't return calls nor emails.
The Siemens rep got very angry and hung up.

In talking to one of them I discovered in their "comparison" that they used the max peak hp WOT rating of an engine.
Which is never used in daily life. Seeing that most diesels are most efficient at around the torque peak,props are geared and boats are built to be run around that torque peak..both my 50' and 70' are like that.
But at the torque peak of say 2500 rpm on a 3500 rpm diesel,the hp will usually be around 3/4 of peak WOT hp.

So as an example:when they'd say " a 9 hp electric is the same as an 18 hp diesel",they really weren't comparing it to the 18 hp WOT diesel,but that one running at lower rpms and therefore lower hp. Say maybe 11 or 12 hp.
So you see they were not quite lying.

They were always going on about the torque this,torque that but an 18 hp diesel ought to put out 25lb. ft of torque around 2500 rpm or so.
Gear it down 3:1 and you have 75 lb.ft.
Close to what their 9hp electric motor would put out...


From Dan Streech the president of Nordhavn

"Some time back, there were some questions and comments about the subject of DE Diesel Electric¯. As most of you know, PAE was involved in two diesel electric projects (N7204 and N7606) and as those of you closest to PAE know, both projects ended in disaster.

The projects stretched over a 4 year period and were a classic slow motion train-wreck involving the usual suspects: flawed assumptions, poor decisions, confusion, extreme complexity, reactionary developments and momentum.

The first mistake was that the basic assumption that efficiency would be gained was dead wrong. Simply said, to use the propulsion engine to make electric power via a generator and then use that power to drive the boat via electric motors brings about a loss of efficiency.
Operation of the boat under battery power- actually pretty stupid in hindsight.

We all know that heat is power, so right there you have lost ground. Having an engineering background, I am almost embarrassed to admit that this simple truism was missed by all of us. Certain basic engineering principals never change and must be respected .

Because passage makers are run for long periods of time at constant speeds, they have none of the above opportunities to recapture energy, so all you are left with are the losses from wasted heat. Furthermore, modern electronically controlled diesel engines maintain their efficiency thru a wide range of loading and RPM.

Operation of the boat under battery power- actually pretty stupid in hindsight.

Ultimately, the systems were ripped out of both boats and those boats were restored to conventional configurations- at a cost of millions In early 2008, PAE sued Siemens for fraud, misrepresentation and a laundry list of failings.

So, case closed, boats fixed and we are back to normal. The above story will explain why it will be many many years (probably beyond my career) before another hybrid project will be undertaken by PAE."

Siemens lost the lawsuit.

OSSA Powerlite system,FEYS,Solomon Tech,and Regenautics?

They exist only in Google searches dating back years...
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Old 01-12-2016, 00:53   #514
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Re: Oceanvolt Hybrid Motor

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Originally Posted by BigBeakie View Post
And the so what is?? What is the effect?
BigBeakie, this is a very good question, interesting for me too and I just asked a ship building engineer about this.
Why is the different torque curve of the electric motor so useful when going against wind and waves?

I have not yet an easy to understand answer - but the point is, that if the boat is slowed down by wind and waves, then the normal prop curve people have in mind is NOT valid anymore (e.g. the propeller load curve in the volvo penta data sheets or the propeller power curves by Yanmar - see below): If the prop no not moving through the water as normal, because the boat is slowed down significantly by external forces, the prop requires more torque than normal for the same rpm.
Combustion engines can not always deliver this torque, which stopps them reaching the higher rpms in such a situation. Thats what I understand so far.

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Old 01-12-2016, 08:55   #515
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Re: Oceanvolt Hybrid Motor

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Originally Posted by 44'cruisingcat View Post
So you believe the claims that by running one electric motor in propulsion, using the power generated by the other in regen mode, a boat can be made to go faster than by sail power alone?
You obviously intended that as a perpetual motion proposal, but in reality the laws of physics don't prevent that from happening, the practical side of engineering however do so.

This is why:

1) when the rotor used as a turbine is in front of the vessel, and it's swept area is something like 10% of cross-sectional area of the vessel, the center of the turbine can also be located near the stagnation point of water flow on the hull. The maximum pressure (dynamic + static pressure) on the hull is already there before the turbine was located there, and it can only be decreased by the turbine. When the turbine is interacting with the water, the force on the water will slow down the apparent water speed on the hull, and decrease skin friction drag on the hull to be less than without the turbine. (In practice the wavemaking drag is way too high, and kills the idea totally, but maybe for a submarine ...)

2) if a propeller is placed behind the hull, it is working in slower water speed than the turbine (due to effects of skin friction of the hull), allowing it to have the same thrust as drag of the turbine, while requireing less power from the shaft than the turbine is producing.
If there were no slip, power P = F*v, and the turbine has more v. Add up slip and less than 100% efficiency, and the prop might not produce more thrust than the drag of the turbine, but due to different speeds, the difference of forces can still be compensated by the reduced drag of the hull.
The equation looks like this:
P_turbine = F_turbine*v_average_turbine*efficiency_turbine
P_prop * efficiency_prop = F_prop*v_average_prop
And since P_turbine=P_prop without any external power sources
F_turbine*v_average_turbine*efficiency_turbine * efficiency_prop = F_prop*v_average_prop
F_prop = F_turbine*v_average_turbine*efficiency_turbine * efficiency_prop / v_average_prop
Where the important part is that v_average_turbine > v_average_prop

3) From the energy point of view, this is not perpetual motion, it is only a reduction of drag of the hull by using a turbine and a prop instead of making the hull having more streamlined shape. In other words, it's all about reducing losses, no energy is being created out of nothing. Understanding well how ddwfttw works certainly helps to understanding this too.

If the idea would be used on a submarine having a very high drag coefficient (>1.0) , it could be proven in practice to work. For a streamlined real world sub it will not work, because the efficiency of prop and turbine are too far away of 100% ideal. And for any real life surface vessel it is even worse.
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Old 01-12-2016, 11:12   #516
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Re: Oceanvolt Hybrid Motor

Quote:
Originally Posted by myocean View Post
BigBeakie, this is a very good question, interesting for me too and I just asked a ship building engineer about this.
Why is the different torque curve of the electric motor so useful when going against wind and waves?

I have not yet an easy to understand answer - but the point is, that if the boat is slowed down by wind and waves, then the normal prop curve people have in mind is NOT valid anymore (e.g. the propeller load curve in the volvo penta data sheets or the propeller power curves by Yanmar - see below): If the prop no not moving through the water as normal, because the boat is slowed down significantly by external forces, the prop requires more torque than normal for the same rpm.
Combustion engines can not always deliver this torque, which stopps them reaching the higher rpms in such a situation. Thats what I understand so far.

Attachment 137251


With respect, I'm calling BS on this one. I have been in more than a few sailboats that were motoring at cruising RPM into big waves. When the boat was slowed I noticed no perceptible change in engine RPM. If a boat was so underpowered that this happens then it should be fixed ASAP.

What happens in a properly powered boat is the prop slips more when the boat slows and may cavitate. An electric system would have to be amazingly smart to sense this condition and slow down the prop to the optimal RPM to stop the cavitation and create maximum thrust. I don't think any EP solution on the market has such a feature. M

So, with respect, I think your ship building engineer is doing the proverbial hand wave.
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Old 01-12-2016, 11:26   #517
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Re: Oceanvolt Hybrid Motor

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Originally Posted by Just Another Sa View Post
You obviously intended that as a perpetual motion proposal, but in reality the laws of physics don't prevent that from happening, the practical side of engineering however do so.

This is why:

1) when the rotor used as a turbine is in front of the vessel, and it's swept area is something like 10% of cross-sectional area of the vessel, the center of the turbine can also be located near the stagnation point of water flow on the hull. The maximum pressure (dynamic + static pressure) on the hull is already there before the turbine was located there, and it can only be decreased by the turbine. When the turbine is interacting with the water, the force on the water will slow down the apparent water speed on the hull, and decrease skin friction drag on the hull to be less than without the turbine. (In practice the wavemaking drag is way too high, and kills the idea totally, but maybe for a submarine ...)

2) if a propeller is placed behind the hull, it is working in slower water speed than the turbine (due to effects of skin friction of the hull), allowing it to have the same thrust as drag of the turbine, while requireing less power from the shaft than the turbine is producing.
If there were no slip, power P = F*v, and the turbine has more v. Add up slip and less than 100% efficiency, and the prop might not produce more thrust than the drag of the turbine, but due to different speeds, the difference of forces can still be compensated by the reduced drag of the hull.
The equation looks like this:
P_turbine = F_turbine*v_average_turbine*efficiency_turbine
P_prop * efficiency_prop = F_prop*v_average_prop
And since P_turbine=P_prop without any external power sources
F_turbine*v_average_turbine*efficiency_turbine * efficiency_prop = F_prop*v_average_prop
F_prop = F_turbine*v_average_turbine*efficiency_turbine * efficiency_prop / v_average_prop
Where the important part is that v_average_turbine > v_average_prop

3) From the energy point of view, this is not perpetual motion, it is only a reduction of drag of the hull by using a turbine and a prop instead of making the hull having more streamlined shape. In other words, it's all about reducing losses, no energy is being created out of nothing. Understanding well how ddwfttw works certainly helps to understanding this too.

If the idea would be used on a submarine having a very high drag coefficient (>1.0) , it could be proven in practice to work. For a streamlined real world sub it will not work, because the efficiency of prop and turbine are too far away of 100% ideal. And for any real life surface vessel it is even worse.
Seems like you're throwing out a bunch of hypotheticals knowing full well that you're omitting reality - fwiw in real life modern submarine hulls have drag coefficient below 0.1, and was basically achieved by the end of WWII. Even early WWII boats had a underwater drag coefficient of around 0.4.
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Old 01-12-2016, 13:23   #518
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Re: Oceanvolt Hybrid Motor

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Originally Posted by SV DestinyAscen View Post
Quote:
You obviously intended that as a perpetual motion proposal, but in reality the laws of physics don't prevent that from happening, the practical side of engineering however do so.
IOW "hypothetical"
...
If the idea would be used on a submarine having a very high drag coefficient (>1.0) , it could be proven in practice to work. For a streamlined real world sub it will not work,
IOW, it doesn't apply to real life submarines.
Seems like you're throwing out a bunch of hypotheticals knowing full well that you're omitting reality - fwiw in real life modern submarine hulls have drag coefficient below 0.1, and was basically achieved by the end of WWII. Even early WWII boats had a underwater drag coefficient of around 0.4.
Seems like you're agreeing completely with Just Another.
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Old 01-12-2016, 13:30   #519
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Re: Oceanvolt Hybrid Motor

Quote:
Originally Posted by Just Another Sa View Post
You obviously intended that as a perpetual motion proposal, but in reality the laws of physics don't prevent that from happening, the practical side of engineering however do so.

This is why:

1) when the rotor used as a turbine is in front of the vessel, and it's swept area is something like 10% of cross-sectional area of the vessel, the center of the turbine can also be located near the stagnation point of water flow on the hull. The maximum pressure (dynamic + static pressure) on the hull is already there before the turbine was located there, and it can only be decreased by the turbine. When the turbine is interacting with the water, the force on the water will slow down the apparent water speed on the hull, and decrease skin friction drag on the hull to be less than without the turbine. (In practice the wavemaking drag is way too high, and kills the idea totally, but maybe for a submarine ...)

2) if a propeller is placed behind the hull, it is working in slower water speed than the turbine (due to effects of skin friction of the hull), allowing it to have the same thrust as drag of the turbine, while requireing less power from the shaft than the turbine is producing.
If there were no slip, power P = F*v, and the turbine has more v. Add up slip and less than 100% efficiency, and the prop might not produce more thrust than the drag of the turbine, but due to different speeds, the difference of forces can still be compensated by the reduced drag of the hull.
The equation looks like this:
P_turbine = F_turbine*v_average_turbine*efficiency_turbine
P_prop * efficiency_prop = F_prop*v_average_prop
And since P_turbine=P_prop without any external power sources
F_turbine*v_average_turbine*efficiency_turbine * efficiency_prop = F_prop*v_average_prop
F_prop = F_turbine*v_average_turbine*efficiency_turbine * efficiency_prop / v_average_prop
Where the important part is that v_average_turbine > v_average_prop

3) From the energy point of view, this is not perpetual motion, it is only a reduction of drag of the hull by using a turbine and a prop instead of making the hull having more streamlined shape. In other words, it's all about reducing losses, no energy is being created out of nothing. Understanding well how ddwfttw works certainly helps to understanding this too.

If the idea would be used on a submarine having a very high drag coefficient (>1.0) , it could be proven in practice to work. For a streamlined real world sub it will not work, because the efficiency of prop and turbine are too far away of 100% ideal. And for any real life surface vessel it is even worse.
Good heavens!

I was simply pointing out one of the unrealistic (and physically impossible) claims the electric motor evangelists make.

That they can make the boat sail faster by using one motor in regen, and feed that power to the other motor.

Obviously doing this would make the boat SLOWER, not faster. If every component were 100% efficient, the best result you could possibly achieve would be no loss, no gain.
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Old 01-12-2016, 14:05   #520
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Re: Oceanvolt Hybrid Motor

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I have been in more than a few sailboats that were motoring at cruising RPM into big waves. When the boat was slowed I noticed no perceptible change in engine RPM.
Cruising RPM means you did by far not make use of the specified maximum power of the diesel and there was obviously still enough torque margin available.
Do you think in those situations you could always increase rpm from cruising rpm up to the maximum?
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Old 01-12-2016, 17:03   #521
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Re: Oceanvolt Hybrid Motor

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Originally Posted by 44'cruisingcat View Post
So you believe the claims that by running one electric motor in propulsion, using the power generated by the other in regen mode, a boat can be made to go faster than by sail power alone?

So therefore a boat in zero wind can go faster than zero knots....


And that people are actually doing this?
Where on earth did you get that from? Put down the bottle...
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Old 01-12-2016, 17:20   #522
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Re: Oceanvolt Hybrid Motor

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Originally Posted by SDChristian View Post
Where on earth did you get that from? Put down the bottle...
There have been claims made that by using one motor in gen mode and feeding that power into the other motor, the boat will sail faster.


Try reading the thread before abusing people. Or maybe make that suggestion to those people.
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Old 01-12-2016, 17:34   #523
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Re: Oceanvolt Hybrid Motor

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Originally Posted by SDChristian View Post
Where on earth did you get that from? Put down the bottle...
LOL, looking back, it was YOU making the claim!
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Old 02-12-2016, 05:53   #524
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Re: OSSA Powerlite System by Glacier Bay

...just wanted to return to this question one more time...


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Originally Posted by beiland View Post
To go back to my original question. Can the generator be made to run enough to supply all of the electrical power required of the propulsion motors?...without the need for big battery banks??

I recognize it might not be the most efficient way to run the boat,...diesel engine running a generator, that in turns provides electrical power for the propulsion motors....at least 2 energy interchanges.

Can the generator/diesel be run at such a variable speed to supply electrical power at either low or high demands?

I thought that this was more of a possibility with DC generators as opposed to AC ones that need to put out a sine-waveform??

I had hopes that these new systems could have two different size generation units (one small, one large) that could cover a whole range of variable outputs for the motor(s).

Here is where I posted that PDF on the OSSA Powerlite system
http://www.cruisersforum.com/forums/...ml#post2267370
...and here is a short excerpt...
Quote:
The reason this approach has not been widely used until now is that the AC current produced by such a genset changes both in frequency and voltage, as the power load and RPM of the engine varies. This makes a permanent magnet genset unsuitable for powering AC motors which require power input stable within a very limited range. It is possible to condition the genset output through the use of power electronics but this adds complexity and cost and is problematic due to the inductive nature of AC motor loads.

OSSA Powerlite generators control the speed of the diesel engine to maintain a desired voltage as the load varies. This desired voltage can be fixed, or it may optionally vary to provide motor speed control to a brush type motor. The AC output is immediately rectified to DC, so that the frequency of the power is not a factor. Major OSSA Powerlite loads are designed to be non- inductive. This can cut the size of the engine required by half because the genset is sized for maximum load, instead of inductive startup loads.

The async operation of the engine means that it is always turning at the optimum speed for a given load. This eliminates wet-stacking and greatly incre ases engine life. It also reduces noise and increases fuel economy, since the engine is no longer required to turn at a fixed high rpm under light load conditions.

If multiple gensets are desired for system redundancy and continuous operation during service, they can be staged to come on or off line as the load conditions change with no concerns about syncing the power frequency.
So can someone explain all of the incorrectness in this PDF ??
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Old 02-12-2016, 08:31   #525
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Re: OSSA Powerlite System by Glacier Bay

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Originally Posted by beiland View Post
...just wanted to return to this question one more time...





Here is where I posted that PDF on the OSSA Powerlite system
http://www.cruisersforum.com/forums/...ml#post2267370
...and here is a short excerpt...
So can someone explain all of the incorrectness in this PDF ??


It is BS to say a variable speed generator cannot power an AC motor. That is patently false. They are trying to justify their choice of DC motors. In the real world AC motors are powered by variable speed controllers that will run from DC.
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