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Old 17-11-2016, 23:54   #376
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Re: Oceanvolt Hybrid Motor

Quote:
Originally Posted by BigBeakie View Post
This (camberless prop blades??) is above my head, I will freely admit. I can say that there is no ICE operating on the boat, at all. The whole purpose of his campaign is to demonstrate that the race can be done using no fossil fuel at all. This boat is not competitive for winning the race as it's a 2005 design which is ancient in IMOCA class, but even so he is leading the slow boats. Everyone ahead of him at this stage is new designs. He is a helluva sailor!

So I believe that it is measured as in your point 2), the kW going into the battery as shown by the OceanVolt controller display.

All the data is being logged in real time by OceanVolt as I've said before, but what the speed to output power values are, I have no idea other than the 2kW at 6.4 knot data point.

If you can deduce that the OceanVolt system has "substantial compromises" that you could easily improve, without knowing the existing engineering, if I were you I'd be sending my CV in to OceanVolt before the race is over.
You wrote this:
"BTW, the OceanVolt projections for Conrad Colemans 60' IMOCA Class were 7.2 knots at 7kW, and that is what was achieved in reality. Another data point that the OceanVolt projection algorith is valuable. But that doesn't mean you can go 10 knots using 10 kW, because it is not straight line, we all know that. In fact for the IMOCA 60 to go 7.8 knots would take about 10kW!! "
And I replied to that.
Are you now saying it reaches that performance using propeller thrust and electric motor with the energy from battery alone instead of ICE connected to a generator?!?

And then you jump to a claim the energy is going in the battery while the propeller is providing propulsion?????????
Either you forgot what your previous post was about or that is total nonsense.

PS, a camberless prop blade is the one with no curvature in cross section, only twist from one cross section to another. Result of a flat plate being a twisted but not bent. Some feathering props are close to those, unlike fixed blades and folding propellers. Also bow thrusters use camberless blades, as they must work equally well in both directions.
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Old 18-11-2016, 00:03   #377
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Re: Oceanvolt Hybrid Motor

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Originally Posted by Jim Cate View Post
BB, I surely agree that 4.5, or even 2 kw is indeed a useful amount of power.
But, how in the world can one extract that much power with literally "no loss of boat speed"? Perhaps no significant loss, but there must be some loss. IMOCA boats are not much limited by hull speed issues, so any time you add drag (and extracting 4.5 Kw must add drag, for there are no free lunches) the boat speed will be reduced. It may well be a desirable trade-off, but some loss must occur.

Jim
2400 N of extra drag is very significant for IMOCA in 6.5 knots of speed.
Some 20 hp inboard diesels provide less thrust at max speed.

Assuming that's insignificant is like saying an IMOCA can tow a 33ft 6ton boat behind it (with sails down and no propulsion other than the towrope) at 6,5 knots and not notice any loss of speed in so light air it only goes 6.5 knots.
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Old 18-11-2016, 00:13   #378
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Re: Oceanvolt Hybrid Motor

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Originally Posted by BigBeakie View Post
Jim,

1) If there is a loss, it is (apparently) not showing up on either Coleman's instruments onboard either on his test sails across the Atlantic, or this Vendee Globe, according to him. It was a primary issue for him deciding on the OceanVolt.
Remember that it is not a feathering prop that is being locked in reverse gear and being dragged thru the water ( drag of that is obvious)

2) it is a folder that is being kept open by a tiny bit of power drawn from the LFP bank , while the water rushing past spins the prop much faster, thus generating a net surplus of charging power.
1) A feathering prop that is being locked in reverse gear has substantially less drag at 6.5 knots than any prop used as a turbine, or even a real optimized turbine providing 2000 W of power at 6.5 knots.

2a) What does LFP bank refer to? (Abbreviation of what)
battery?
2b) So you are saying the shaft has simultaneously 2 opposing torques acting, one providing the power to keep the blades open and the opposing providing the power generating electricity?
Does the shaft also twist in 2 opposing directions at the same time and place as well?!?
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Old 18-11-2016, 00:35   #379
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Re: Oceanvolt Hybrid Motor

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Originally Posted by fabgo View Post
OceanVolt makes the claim that their 15kW motor is equivalent to a 45 hp diesel engine, reasoning:

"The torque of the electric motors is higher than that of a diesel motor and they both have the same size propeller"

I compared the specs of the OceanVolt 15 and the 4JH45 Yanmar diesel. The Oceanvolt spins at a max 2200 RPM. The Yanmar produces about 13kW at the same RPM.

So the claim seems accurate. The OceanVolt 15 kW is roughly equivalent to a Yanmar 45 hp diesel at 2200 RPM. And 2200 RPM I guess is close to a typical cruising speed.

Of course the Yanmar goes up to 3000 RPM, which is power that the OceanVolt 15 does not have. Thus the claim that the OceanVolt will be about 1 knot slower at max speed (I assume this will vary depending on the boat).

So the question then becomes whether one needs those extra 800 RPM (and the 2x power that comes with it). I don't have enough experience, as I have never had to max out the engines against strong seas, so I don't know how important this is.

Of course one would need a 30 kW generator run these motors for any length of time...

- Fabian
The Yanmar produces 13 kW at 2200 RPM with a prop optimized for max power.

It is capable of providing 28 kW at prop shaft at 2200 RPM and does so at WOT if the prop is selected for that for max efficiency and that power is enough in any and all conditions and any negative effect on engine life is ignored. (max torque extends at that rpm and no further, indicating where rpm for max efficiency extends to). The result would also be like in the tug of war video discussed earlier in this thread or even worse.
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Old 18-11-2016, 01:23   #380
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Re: Oceanvolt Hybrid Motor

Quote:
Originally Posted by Just Another Sa View Post
You wrote this:
"BTW, the OceanVolt projections for Conrad Colemans 60' IMOCA Class were 7.2 knots at 7kW, and that is what was achieved in reality. Another data point that the OceanVolt projection algorith is valuable. But that doesn't mean you can go 10 knots using 10 kW, because it is not straight line, we all know that. In fact for the IMOCA 60 to go 7.8 knots would take about 10kW!! "
And I replied to that.
Are you now saying it reaches that performance using propeller thrust and electric motor with the energy from battery alone instead of ICE connected to a generator?!?

And then you jump to a claim the energy is going in the battery while the propeller is providing propulsion?????????
Either you forgot what your previous post was about or that is total nonsense.

PS, a camberless prop blade is the one with no curvature in cross section, only twist from one cross section to another. Result of a flat plate being a twisted but not bent. Some feathering props are close to those, unlike fixed blades and folding propellers. Also bow thrusters use camberless blades, as they must work equally well in both directions.
Let's back up. I don't understand what your issue is, but I see a possible confusion. There was a projection done by OceanVolt, as given. I'm looking at it now to check my figures. Coleman in practice sessions and to test equipment would have run the SD15 in propulsion.

BUT, he is now in a race where the rules do not allow him to run an engine for propulsion, otherwise he is disqualified. In the case of an emergency, he could run the SD15 off his LFP bank and/or DC genset, eg he's dismasted, or needs to motor to go rescue another racer.So during the race there is an electronic lock on the EP and the SD15 is used ONLY as a hydrogenerator.

I hope that is now clear?
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Old 18-11-2016, 01:51   #381
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Re: Oceanvolt Hybrid Motor

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Originally Posted by fabgo View Post
I doubt that 2kW at 6.5 knots is correct.

Here is some data straight from the horse's mouth:

Create energy while sailing

According to the chart provided by OceanVolt, a boat speed in excess of 9 knots is required to generate 1000 watts. (For a single motor, so 2kW on a catamaran.)

Still, that's not bad at all.

- Fabian
My apologies and mea culpa. You are, Sir, completely correct! I made a booboo by looking at the scale on my catamaran projection of regen for 2x SD15's at 6.5 and it is 2kW.

Colemans's is 1 kW at 6.5 since he has one motor on regen, not two.

Sorry for the confusion
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Old 18-11-2016, 11:24   #382
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Re: Oceanvolt Hybrid Motor

IMHO fuel cells may be the future of electric propulsion.

https://en.m.wikipedia.org/wiki/Yacht_XV_1_(hydrogen)#

As noted in the article, this prototype was not completed and it seems the tech is not quite ready for prime time.

The CO2 produced in the production of hydrogen is a major stumbling block at present as are other factors.

I have enjoyed many an R&D project. Ideas that don't work out often lead to better ideas but are still a source for heartbreak.

"I have not failed. I've just found 10000 ways that won't work." - Thomas A. Edison

To many sailing plans end up in heart break even without planning to use unproven tech on critical systems.

Are you hoping to be another T.A. Edison or are u wanting cruise?
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Old 18-11-2016, 11:55   #383
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Re: Oceanvolt Hybrid Motor

Electric propulsion is a reality, just not yet to the scale we are looking at. Look at an aircraft carrier. It uses electric motors for propulsion, but it has a nuclear reactor producing steam, to turn a steam turbine and generator at a constant RPM which is the most efficient way to produce power.

Our problem is scale (weight) and cost. The motors themselves are relatively light. The weight issue seems to be in the proper sizing of the generator and battery bank to minimize generator run time.

Currently I do not think in a sailing vessel of the size we are talking an electric Hybrid system can keep up with direct drive diesels that are called on for motoring through the night or whatever may be the case. You add to much weight to a catamaran and you'll never get her sailing and you will always be motoring.

However for some people a hybrid electric drive system may be a huge cost savings when all the components in it are designed to the individuals way of life aboard a boat.

People who spend most of their time cruising between islands in the Caribbean and living off hook while not limiting times and use of electrical equipment. With the right size battery system and generator charging system you could run your generator for an hour or two every 12 hours and never have to worry about the efficiency. Currently if you want to run your AC system your dependent on your generator to make the power, but a properly sized battery pack could run your AC overnight without ever having the generator kick on. Wake up in the morning and run your generator for a couple of hours and your ready to go again. Less start and stops on your generator also increases the life of the Gen set. A gen sets least efficient time is when it is first started. Also every start uses power to spin the starter. The more you look at all the little things and the more you realize the hybrid system could be a better option for some people.

I know a couple people with electric cars that work fine for them. They are lucky to drive 100 miles in a day and the heaviest thing they carry are groceries. Me on the other hand drive 300 miles or more a couple days a week and I haul test equipment that can total up to several hundred pounds at a time. I drive a full size truck. I also got a crew cab and added the leather heated and cooled seats and bose sound system not cause I needed them, but I like them. Yea the electric car owners sometimes complain about how much fossil fuel my truck uses until of course they need something hauled.
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Old 19-11-2016, 08:36   #384
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Re: Oceanvolt Hybrid Motor

Quote:
Originally Posted by fabgo View Post
OceanVolt makes the claim that their 15kW motor is equivalent to a 45 hp diesel engine, reasoning:

"The torque of the electric motors is higher than that of a diesel motor and they both have the same size propeller"

I compared the specs of the OceanVolt 15 and the 4JH45 Yanmar diesel. The Oceanvolt spins at a max 2200 RPM. The Yanmar produces about 13kW at the same RPM.

So the claim seems accurate. The OceanVolt 15 kW is roughly equivalent to a Yanmar 45 hp diesel at 2200 RPM. And 2200 RPM I guess is close to a typical cruising speed.

Of course the Yanmar goes up to 3000 RPM, which is power that the OceanVolt 15 does not have. Thus the claim that the OceanVolt will be about 1 knot slower at max speed (I assume this will vary depending on the boat).

So the question then becomes whether one needs those extra 800 RPM (and the 2x power that comes with it). I don't have enough experience, as I have never had to max out the engines against strong seas, so I don't know how important this is.

Of course one would need a 30 kW generator run these motors for any length of time...

- Fabian
This is the type of misinformation and half truths that make these discussions difficult for those who want so badly for electric to be viable and make objective people assume the oceanvolt and similar companies are selling snake oil.

You can take a 15kw electric motor and claim it's equivalent to a 1000hp engine if you limit the throttle setting on the 1000hp engine so it can't produce more than 15kw (that actually may be hard because it's probably producing more than 15kw at idle but the point still stands).

What they are really saying is you don't need a 45hp engine...which may or may not be true. But if you only need 15kw, you can provide that with a diesel engine of 15kw and then use a gear reduction to get the same torque at the prop and run the same size prop as the electric to get the same performance with the exception of acceleration where the electric will have a slight edge due to low RPM torque (which we've already established as not a critical performance criteria).

The reality is the 45hp diesel can go beyond the 2200rpm rpm limit and when fighting head winds, current and wave, it is often done. If buyers didn't want the extra HP, you would see these boats outfitted with 20hp diesels as it would save the manufacturers some up front costs.
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Old 19-11-2016, 12:19   #385
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Re: Oceanvolt Hybrid Motor

It's because of the legendary electric superhorses.
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Old 19-11-2016, 22:28   #386
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Re: Oceanvolt Hybrid Motor

In this discussion of EP & diesel propulsion, I wish we could move it from HP & kW to the more meaningful metric that I think really matters, and that is thrust. Isn't that what really matters when wanting to assess what size and type of propulsion is needed to do the job?

At the end of the day I need to know how must thrust it takes to push my new cat of x displacement and y wind resistance against various windspeeds.

This is all about torque as I hope we can all agree because it is very closely related to "pushing power" against a force.

We know that petrol outboard engines produce high revs of a fairly small propellerr to push a (relatively) light planing hull fast and have (relatively) low torque.
Diesels have somewhat lower revs and more torque for pushing a heavier displacement hull though the water.
Electric motors have even lower revs and more torgue again for even greater pushing power.
And there used to be steam engines which represented the pinnacle of this progression of rev - torque - thrust.

This video shows this relationship except it is in the context of the dreaded and highly controversial tug of war demonstration that some find so objectionable here. It's between an 18HP steam tractor from 1880 and an 800HP diesel John Deere. So for effective work like pulling stumps or very heavy machinery, the steam engine pulls the diesel backwards. And note that the diesel was warmed up and at higher revs so presumably at it's effective torque when it was pulling the steam tractor (that was in neutral) backwards. Then the steamer engages gear and stops the diesel in its tracks and pulls it backwards.




The point is, torque trumps horsepower (sorry, couldn't resist) for pulling or pushing power, doesn't it? So why not go with EP for effective thrust for pushing against wind???
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Old 19-11-2016, 23:44   #387
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Re: Oceanvolt Hybrid Motor

[QUOTE=BigBeakie;


The point is, torque trumps horsepower (sorry, couldn't resist) for pulling or pushing power, doesn't it? So why not go with EP for effective thrust for pushing against wind???[/QUOTE]

Love the Video.

I assume you are joking though.

Nothing to do with horsepower or torque , its all to do with TRACTION.

Little tractors little wheels are SPINNING.

Very Funny
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Old 20-11-2016, 00:29   #388
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Re: Oceanvolt Hybrid Motor

A basic physics lesson:

1. Thrust or Torque are both measure of Force. Common units are pounds or kilograms.

2. Work is the application of Force over a Distance. Comparable units are foot pounds or Kilogram meters.

3. Power is the rate at which Work is done. (i.e the additional dimension of Time). Comparable units are Foot Pounds per hour or Kilogram meters per second. (Usually expressed as HP or kW by simple arithmetic conversion factors.).

From 2 above:
A boat engine needs to do Work to move a boat against the drag of water and wind.
From 3 above:
The faster you want it to move, the more Power you need.

Regardless of what form of propulsion you use:
If you want to move a boat 5NM in 1 hour, you need a certain amount of Power.
To provide a fixed amount of Power over a fixed time, you need to do the same amount of Work.
To achieve a fixed amount of Work over a fixed distance, you need the same amount of Force.

By concentrating on static Force ("pulling power"), you are completely ignoring time and distance, the two critical components when moving a boat.

Bottom line: Power is Power, regardless of the method of providing it. EP and diesel HorsePower or kW are the same thing and the same amount is needed to move a boat at x knots.



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Old 20-11-2016, 00:36   #389
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Re: Oceanvolt Hybrid Motor

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Originally Posted by Seaslug Caravan View Post
Love the Video.

I assume you are joking though.

Nothing to do with horsepower or torque , its all to do with TRACTION.

Little tractors little wheels are SPINNING.

Very Funny
Yep a perfect demonstration of the frangibility of soil and the benefits of weight and surface contact area, but it says absolutely nothing about force, work or power.
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Old 20-11-2016, 02:34   #390
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Re: Oceanvolt Hybrid Motor

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Yep a perfect demonstration of the frangibility of soil and the benefits of weight and surface contact area, but it says absolutely nothing about force, work or power.
So an 18HP petrol/gasoline powered tractor with the same weight and wheels as the steam tractor shown, would be able to drag the 800HP John Deere backwards, eh?

HP is HP, Power is Power, regardless of the method of providing it.
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