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Old 18-09-2016, 07:35   #61
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Re: Oceanvolt Hybrid Motor

Making decisions based on savings in fuel costs on a cruising yacht is a dichotomy of monumental proportions.

The OP's plan will not save fuel over a well designed cat. A hybrid using two generators and two electric drive motors will weigh more and require more fuel. It's impossible to have enough batteries to store a meaningful amount of solar power for long motoring trips.

Around the islands a well experienced sailor can slip from one island to the next using evening and early morning off/on shore breezes and use no fuel for propulsion. No hybrid system can beat a light, well sailed boat (cat or mono) using what nature provides for free.

A hybrid would seem to only make sense if a single engine/generator (which is much lighter than 2 engines of half the energy rating) drives 2 electric motors. Then there is only one consumer of diesel for all energy needs. A specially designed engine could run on 3 cylinders or 6 and be efficient under several scenarios. It has to be super reliable because you have all your eggs in one basket. If you try to build a hybrid system with redundancy then it no longer makes sense on any front.
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Old 18-09-2016, 10:49   #62
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Re: Oceanvolt Hybrid Motor

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Originally Posted by valhalla360 View Post
In your hypothetical question, it will burn slightly more fuel with a hybrid and dead batteries. (assuming both boats are set up to run at peak efficiency at 7kts). Properly set up, it will come close but at significant increased up front costs and it will be overkill for house loads.

Where the proponents come up with supposed improvements in propulsion efficiency is they cut the HP of the hybrid system drastically and accept maybe a 4kt cruise speed and then compare that to the conventionally powered boat doing 7kts ignoring the fact that if 4kts was all you ever need, you could simply use smaller conventional diesels and get better improvements in efficiency.
A general version of my answer is included in the OceanVolt FAQ. 300 liters gets you 600-700 nm. That seems promising to me once you factor back in the benefits; you should sail slightly faster with the hybrid tech due to the props pushing you up swells and regenerating down the backside, loads of comfortable power for amenities along the journey, and silent operation for bursts of 40-60 nm on batteries alone (which usually will then be recharged via the prop regen and solar). I have no idea why there is so much resistance to this tech amongst this crowd unless of course you think the company is just plain lying. If it is as advertised it seems like a winner. It's a new tech so of course there will be early adopter bugs, but the principle seems sound.
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Old 18-09-2016, 12:02   #63
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Re: Oceanvolt Hybrid Motor

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Originally Posted by SDChristian View Post
A general version of my answer is included in the OceanVolt FAQ. 300 liters gets you 600-700 nm. That seems promising to me once you factor back in the benefits; you should sail slightly faster with the hybrid tech due to the props pushing you up swells and regenerating down the backside, loads of comfortable power for amenities along the journey, and silent operation for bursts of 40-60 nm on batteries alone (which usually will then be recharged via the prop regen and solar). I have no idea why there is so much resistance to this tech amongst this crowd unless of course you think the company is just plain lying. If it is as advertised it seems like a winner. It's a new tech so of course there will be early adopter bugs, but the principle seems sound.
Simple, I think the hybrid companies are lying. Or if not lying they are making grossly unjustified comparisons.

The entire 'electric hp are bigger' argument comes directly from advertising material. And is absolute and complete crap. It has been beaten to death, but in short boats are prop size constrained, so extra torque has zero effect on performance.

Or the 'up to X nm range' which is usually quoted at 1kn or less in dead flat water and zero wind. Yes, technically it's true, but it's also grossly dishonest. It also generally doesn't quote the number and weight of the battery bank required.

Regeneration... Just like all towed generators needs about 5kn of boat speed to work well. Less than this and the prop size needed goes up quickly and drag goes up even faster. It works but not as well as people seem to think. Practically it's only been shown to work when average speeds are high, NOT when motors sailing at the boarder line.

Solar/wind collection... This completely misses the amount of power that a boat needs to move. Most boats will use every drop of power that can be produced in 2-3 hours at cruise speed. It simply isn't possible to generate a meaningful amount of power for propulsion from renewables.

There are special use applications where electric or hybrid systems are desirable. Where the trips are short and then you can plug in to shore power. But beyond this we are not even close to the storage required for it to work. solar panels are currently about 20% efficient, they need to get closer to 60% to generate enough power for propulsion. And energy density of batteries is currently about 2% of liquid fuels, that needs to climb to about 10%.

We aren't even close right now, and even the best stuff on the drawing board isn't close.
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Old 18-09-2016, 13:57   #64
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Re: Oceanvolt Hybrid Motor

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Originally Posted by SDChristian View Post
A general version of my answer is included in the OceanVolt FAQ. 300 liters gets you 600-700 nm. That seems promising to me once you factor back in the benefits; you should sail slightly faster with the hybrid tech due to the props pushing you up swells and regenerating down the backside, loads of comfortable power for amenities along the journey, and silent operation for bursts of 40-60 nm on batteries alone (which usually will then be recharged via the prop regen and solar). I have no idea why there is so much resistance to this tech amongst this crowd unless of course you think the company is just plain lying. If it is as advertised it seems like a winner. It's a new tech so of course there will be early adopter bugs, but the principle seems sound.
Probably not an outright lie just a horrible distortion of the truth which may as well be a lie.

I get that kind of range with a gasoline engine powered catamaran. Hardly anything special. (just like oceanvolt, I let you figure out the details of boat size, assumed speed and water conditions but I'm not lying.)

There's no resistance to the idea. The resistance is to false promises. If it worked, we would all jump on the bandwagon. The principal is simply not sound and no amount of hoping and wishing is going to change that. The use case is totally different from a hybrid car getting great mileage in stop & go traffic.
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Old 18-09-2016, 14:11   #65
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Re: Oceanvolt Hybrid Motor

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Originally Posted by valhalla360 View Post
Probably not an outright lie just a horrible distortion of the truth which may as well be a lie.

I get that kind of range with a gasoline engine powered catamaran. Hardly anything special. (just like oceanvolt, I let you figure out the details of boat size, assumed speed and water conditions but I'm not lying.)

There's no resistance to the idea. The resistance is to false promises. If it worked, we would all jump on the bandwagon. The principal is simply not sound and no amount of hoping and wishing is going to change that. The use case is totally different from a hybrid car getting great mileage in stop & go traffic.
Debate is useless when one party is convinced that the data are false.
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Old 18-09-2016, 14:48   #66
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Re: Oceanvolt Hybrid Motor

You might go slightly faster up the waves, but you'll also go slower down them. There's no free ride.


The overall net effect would be that you go slower, not faster. Because no system is 100% efficient, you'd take more energy out than you could return.
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Old 18-09-2016, 16:19   #67
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Re: Oceanvolt Hybrid Motor

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You might go slightly faster up the waves, but you'll also go slower down them. There's no free ride.


The overall net effect would be that you go slower, not faster. Because no system is 100% efficient, you'd take more energy out than you could return.
I guess these guys were lying too: "I call it putting the motors in step," says Scott. "If you set it just right, you get Scott. "If you set it just night, you get a zero net use of electricity. And you also get an additional one-half to one knot of boat speed. There's a net speed increase,"

http://www.catamarans.com/news/2004/03/waypoint.asp

It's impossible to debate when real world examples are rebutted with "they're lying". Could it be possible that everyone is not lying?
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Old 18-09-2016, 18:09   #68
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Re: Oceanvolt Hybrid Motor

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I guess these guys were lying too: "I call it putting the motors in step," says Scott. "If you set it just right, you get Scott. "If you set it just night, you get a zero net use of electricity. And you also get an additional one-half to one knot of boat speed. There's a net speed increase,"

First Electric Lagoon Crosses Atlantic

It's impossible to debate when real world examples are rebutted with "they're lying". Could it be possible that everyone is not lying?

that fact that this is a 2004 "news" article to the link says a lot,

sadly the "Marine Electric Propulsion" has had some pretty rough years with false claims so will take some time to revisit to convince the general yachting community , let alone any significant production boat manufacturer to jump on board.
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Old 18-09-2016, 18:23   #69
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Re: Oceanvolt Hybrid Motor

Quote:
Originally Posted by SDChristian View Post
I guess these guys were lying too: "I call it putting the motors in step," says Scott. "If you set it just right, you get Scott. "If you set it just night, you get a zero net use of electricity. And you also get an additional one-half to one knot of boat speed. There's a net speed increase,"

First Electric Lagoon Crosses Atlantic

It's impossible to debate when real world examples are rebutted with "they're lying". Could it be possible that everyone is not lying?
Perhaps not lying, but falsely observing and/or reporting what happens. GAining speed without net use of energy seems to violate some basic laws of physics, without even introducing the idea of frictional losses in the regeneration equipment, electrical losses in the wiring, chemical losses in the charge/discharge cycle and so on.

Or perhaps we have a semantic disconnection here, and this chap is saying that you can motorsail (electric motors) using exactly the amount of power that is generated by the solar system and gain some speed without draining the batteries... which seems quite possible. But I don't think one can gain power from regeneration surfing down waves without loosing power (slowing down) going up the back side of those waves.

And finally, the idea that using regeneration while sailing will not slow the boat down significantly is wrong, except in a situation where in quite strong winds the boat has sufficient sail power to stay at hull speeds even when regenerating. Extracting power by turning the propellers/generators takes energy, pushing the boat through the water takes energy. There is only so much power developed by the sails. If you use some of it to generate electricity, there is less left to push the boat, so you slow down.

I won't comment additionally about the ideas of a ton of solar panels suspended well above the waterline, nor about the fitting of one or more giant wind turbines some 15 to 20 feet above the w/l... the effects of such upon the sailing performance and stability of any vessel will be considerable and not favorable.

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Old 18-09-2016, 18:57   #70
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Re: Oceanvolt Hybrid Motor

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Originally Posted by Jim Cate View Post
Perhaps not lying, but falsely observing and/or reporting what happens. GAining speed without net use of energy seems to violate some basic laws of physics, without even introducing the idea of frictional losses in the regeneration equipment, electrical losses in the wiring, chemical losses in the charge/discharge cycle and so on.

Or perhaps we have a semantic disconnection here, and this chap is saying that you can motorsail (electric motors) using exactly the amount of power that is generated by the solar system and gain some speed without draining the batteries... which seems quite possible. But I don't think one can gain power from regeneration surfing down waves without loosing power (slowing down) going up the back side of those waves.

And finally, the idea that using regeneration while sailing will not slow the boat down significantly is wrong, except in a situation where in quite strong winds the boat has sufficient sail power to stay at hull speeds even when regenerating. Extracting power by turning the propellers/generators takes energy, pushing the boat through the water takes energy. There is only so much power developed by the sails. If you use some of it to generate electricity, there is less left to push the boat, so you slow down.

I won't comment additionally about the ideas of a ton of solar panels suspended well above the waterline, nor about the fitting of one or more giant wind turbines some 15 to 20 feet above the w/l... the effects of such upon the sailing performance and stability of any vessel will be considerable and not favorable.

Jim
Gaining speed without net use of energy does not violate any laws of physics when there is a huge friggin sail collecting lots of energy.
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Old 18-09-2016, 19:02   #71
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Re: Oceanvolt Hybrid Motor

The only believable claim is one that does not imply a perpetual motion machine.

If we assume wind force is a constant, introduce drag in the form of a generator = energy generated in electricity, electricity used to power motor cannot increase boat speed beyond drag introduced.
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Old 18-09-2016, 19:10   #72
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Re: Oceanvolt Hybrid Motor

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The only believable claim is one that does not imply a perpetual motion machine.

If we assume wind force is a constant, introduce drag in the form of a generator = energy generated in electricity, electricity used to power motor cannot increase boat speed beyond drag introduced.
I would have thought this went without saying, but the "net energy" mentioned is referencing the battery state not "boat energy". The charge of the battery does not drop once you average out the drain vs charge for a given stretch.
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Old 18-09-2016, 19:17   #73
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Re: Oceanvolt Hybrid Motor

Assuming 100% generator/motor unit efficiency and ideal supercapacitator capabilities, the vessel would maintain constant velocity better in swells, but be slower than the same non-displacement hull without the gear?
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Old 18-09-2016, 19:24   #74
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Re: Oceanvolt Hybrid Motor

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Assuming 100% generator/motor unit efficiency and ideal supercapacitator capabilities, the vessel would maintain constant velocity better in swells, but be slower than the same non-displacement hull without the gear?
And what if the wind was pushing said boat at a sufficient speed to result in the prop regenerating more power than was used during each spurt of power?
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Old 18-09-2016, 19:35   #75
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Re: Oceanvolt Hybrid Motor

Assuming zero weight, 100% efficiency at generation, storage, conversion from electrical potential to kinetic again, it would have same avg speed. Fewer changes in velocity.

Problem is with the assumptions.
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