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Old 31-12-2019, 00:18   #1981
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Re: Oceanvolt Hybrid Motor

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Originally Posted by StuM View Post
I'd expect more than that.


I push my 12m LWL, approx 10 ton cat at just over 4 kt with 5HP (one engine at 2000 RPM), your formula says only 2.5 kt.
Hi Stu, what size are your engines? Only 5hp at 2000rpm seems very low.
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Old 31-12-2019, 02:40   #1982
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Re: Oceanvolt Hybrid Motor

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Hi Stu, what size are your engines? Only 5hp at 2000rpm seems very low.

Yanmar 3JH3E 40HP. That's the factory figure for "propeller power" at 2000 RPM
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Old 02-01-2020, 11:28   #1983
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Re: Oceanvolt Hybrid Motor

My apologies for not reading the entire thread (only about the first 1/3rd), and therefore potentially asking a question for the nth time.

One of the biggest advantages of the hybrid system is to run a diesel generator at an optimum rpm and load, whereas diesel driven units are notoriously unlikely to be operating at peak or near-peak efficiency in terms of load vs rpm.

How much does a variable pitch propeller change this equation back in favor of diesel power systems? You can set an rpm and then choose pitch based on need or efficiency depending on circumstance... forward and reverse propulsion can be dialed in with fairly rapid changes in pitch resulting in good close quarters maneuvering, and engine temps (or a chart of usual settings) can be used to select efficient pitch for a given rpm resulting in high efficiency and low carbon deposits.

Yep, they add more up front $, but can VPPs give reliable and important bang for boat buck?
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Old 02-01-2020, 13:06   #1984
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Re: Oceanvolt Hybrid Motor

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Originally Posted by StuM View Post
Yanmar 3JH3E 40HP. That's the factory figure for "propeller power" at 2000 RPM
Kelsall's estimates are for engine HP, much more sensible answers. It must be stressed that they just give an estimate.
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Old 02-01-2020, 14:20   #1985
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Oceanvolt Hybrid Motor

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Originally Posted by phillysailor View Post
My apologies for not reading the entire thread (only about the first 1/3rd), and therefore potentially asking a question for the nth time.

One of the biggest advantages of the hybrid system is to run a diesel generator at an optimum rpm and load, whereas diesel driven units are notoriously unlikely to be operating at peak or near-peak efficiency in terms of load vs rpm.
Look at fuel consumption of a diesel engine with a fixed pitch prop. A Yanmar 4JH5E propeller power curve vs. RPM and fuel consumption vs. RPM are almost identically shaped.

At 5.5kW propeller power fuel is about 1.75 L/hr or about 0.318 L/kW. At 16.5kW the fuel consumption is 4.5L/hr or 0.272 L/kW. There is no “peak efficiency” point in terms of fuel consumption vs. HP. Efficiency simply goes up the higher you run the HP. Diesels are most efficient at WOT.

Thus variable pitch props don’t save much on fuel.

Variable props do help in low speed maneuvering and in reversing situations. But no one cares about fuel consumption in those limited cases.

Electric power trains driven by internal combustion engines are slightly less efficient than direct mechanical drive.

Electric drive can be more “efficient” on fossil fuel if huge amounts of solar power is available.
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Old 02-01-2020, 20:44   #1986
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Re: Oceanvolt Hybrid Motor

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Originally Posted by phillysailor View Post
. . .One of the biggest advantages of the hybrid system is to run a diesel generator at an optimum rpm and load, whereas diesel driven units are notoriously unlikely to be operating at peak or near-peak efficiency in terms of load vs rpm.. .

This was discussed up thread. In fact, if you look at a fuel map, you are unlikely to be using a generator at optimum load in a hybrid application. Optimum efficiency generally takes place at approximately the torque peak of the engine, and at somewhat less than maximum output for that RPM. Naturally you will size a diesel generator for a hybrid application at less than the size a normal propulsion engine would be, so you will normally be operating it at its max output, which is not indeed going to be anything like its "peak or near peak efficiency". Better operating regime for the diesel might be an advantage of hybrid drive, but this advantage will be slight if it exists at all, and in many cases a hybrid drive will be using the diesel engine in a less efficient regime than mechanical drive. No way any efficiency gain, even in an ideal case, can make up for the conversion losses from mechanical to electrical power and then back.
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Old 03-01-2020, 19:17   #1987
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Re: Oceanvolt Hybrid Motor

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One of the biggest advantages of the hybrid system is to run a diesel generator at an optimum rpm and load, whereas diesel driven units are notoriously unlikely to be operating at peak or near-peak efficiency in terms of load vs rpm.
This is true for cars...in city driving, you go from zero power needed at a stop light to high demand accelerating to light load cruising at 25-40mph to zero power braking at the next light...and you go thru this cycle maybe once a minute...result is much of the time the engine is not producing the ideal amount of power relative to efficiency. (freeway operations - hybrids don't gain much of an advantage)

With your average displacement cruising boat, once you clear the marina, you throttle up to cruising speed and leave it there until you reach your destination. Result is that for better than 95% of the time, the motor is running at cruising speed which unless you wildly oversize the motor, you are well into the efficient power range of the motor...there is little or no efficiency improvement to be had...on top of that, with a hybrid, the conversion of mechanical to electrical to battery then back to electrical to mechanical will pretty much guarantee the hybrid loses any small advantage from running the motor at ideal output.
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Old 03-01-2020, 23:03   #1988
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Re: Oceanvolt Hybrid Motor

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Look at fuel consumption of a diesel engine with a fixed pitch prop. A Yanmar 4JH5E propeller power curve vs. RPM and fuel consumption vs. RPM are almost identically shaped.

At 5.5kW propeller power fuel is about 1.75 L/hr or about 0.318 L/kW. At 16.5kW the fuel consumption is 4.5L/hr or 0.272 L/kW. There is no “peak efficiency” point in terms of fuel consumption vs. HP. Efficiency simply goes up the higher you run the HP. Diesels are most efficient at WOT.

Well, that's not true at all. See the fuel map above. Diesels are most efficient at around that RPM where their torque peak is, and about 70%-80% maximum load at that RPM.




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Thus variable pitch props don’t save much on fuel.

Variable pitch props can save a fair good bit of fuel, depending on what kind of operating regime you have. If you need 50% or more of the engine's rated power and you can get that into a fixed pitch propeller -- so undersized engine and overpropped, compared to typical cruising boat configuration -- then you won't save much fuel with a variable pitch prop.



But if you have typical engine power (4 to 5 hp/metric tonne) and often cruise at at well below hull speed, then a variable pitch prop can save quite a lot of fuel, maybe 20% or 30% or even more. But besides saving fuel, you can operate the engine at lower speed (for the same load), so quieter and more pleasant, and healthier for the engine since cylinder temps will be higher. The other great benefit of variable pitch props is motor-sailing.
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Old 28-04-2020, 05:12   #1989
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Re: Oceanvolt Hybrid Motor

It has been mentioned that a performance cat is the best case for an electric set up. Just so happens that the owner of Balance Catamarans posted a video about creating an electric 526, which is one heck of a performance cat (and my dream boat if I strike it big!):

https://youtu.be/e0q98-JQPLk

tl;dw: all electric isn’t ready for a cruising boat because storage isn’t dense enough and solar not efficient enough to create the range required or provide the “get out of jail card” of a diesel. And once you add a generator, your weight is at least equal to a “normal” set up, and your cost and complexity are orders of magnitude higher.
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Old 28-04-2020, 11:08   #1990
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Re: Oceanvolt Hybrid Motor

If you are doing extrem thing like the guy mentioned in the video, who wanted to go to Antarctica, you should have a backup.
But if you are not on a shedule and have enough time, why not.
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Old 28-04-2020, 23:07   #1991
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Re: Oceanvolt Hybrid Motor

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If you are doing extrem thing like the guy mentioned in the video, who wanted to go to Antarctica, you should have a backup. But if you are not on a shedule and have enough time, why not.
Why not? Because you don't have to be in Antarctica to have a situation arise where you need immediate propulsion power, but your batteries might be low (for any number of different reasons)...

I'm all for this technology, I'm trying to figure out how to incorporate it on my next boat but within more of a budget (electric outboards at around 30-50% of the cost of Torqeedo may be a option), but I still plan to incorporate a small genset (possibly a Honda type, I'm still considering) to provide ultimate backup even if the primary power source will be solar.

I'm also a 'real' sailor who advocates always being ready to sail if required, and beat off a lee shore if necessary, as well as sail in and out of the anchorage, channels, marinas, etc (and I have done all of this in emergencies and/or as standard procedure).

But for real cruising (not daysailing) the technology is simply not quite there yet, which is exactly what the video says.

I guess an option could be to have a 'reserve' battery bank, which is always charged and kept isolated from normal use, for emergency propulsion purposes.

But with the weight and cost of that you might as well just have the Honda type genset which would also cover the periods of low solar production, etc.

And in real life cruising you still end up motoring quite a lot even if you think you have no schedule. Sometimes there is simply no wind.

I follow @CatNewBee's thread with great interest, he has really shown what is possible with solar and all the modern liveaboard conveniences, but he still has a genset backup, and ice propulsion.

As I said, I want to see this technology succeed, I want to use it myself, but at the moment it's not a 100% solution yet, and this is what the video makes clear too.

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Old 29-04-2020, 02:58   #1992
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Re: Oceanvolt Hybrid Motor

If you look at the speed of the changes in battery technology, then I think it's likely that there will be a solution available in a not too far future.
Take the Renault Zoe for instance, it startet in 2012 with a 22kWh battery and has now, for the same price and the same space, 52kWh. So capacity has almost doubled.
And it's not the only one, BMW i3, VW eUp, Nissan Leaf (that almost tripled the capacity within 10 years).
Yes, they are using technology that I would not want on a boat, especially not in a DIY environment. Torqueedo uses the Samsung cells that BMW uses in the i3 for all batteries from the Power 48-5000 up.
But I am sure that also LFP cells will get better and cheaper over time.
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Old 29-04-2020, 05:04   #1993
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Re: Oceanvolt Hybrid Motor

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If you look at the speed of the changes in battery technology, then I think it's likely that there will be a solution available in a not too far future.
A solution for an average sized cruising yacht that equals or exceeds the range of diesel or petrol (in all conditions - not just sunny tropical cruising) is still pretty far away.

But I agree that interim solutions are already available, and improving all the time, and that's a good thing.

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Old 29-04-2020, 06:21   #1994
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Re: Oceanvolt Hybrid Motor

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If you look at the speed of the changes in battery technology, then I think it's likely that there will be a solution available in a not too far future.
Take the Renault Zoe for instance, it startet in 2012 with a 22kWh battery and has now, for the same price and the same space, 52kWh. So capacity has almost doubled.
And it's not the only one, BMW i3, VW eUp, Nissan Leaf (that almost tripled the capacity within 10 years).
Yes, they are using technology that I would not want on a boat, especially not in a DIY environment. Torqueedo uses the Samsung cells that BMW uses in the i3 for all batteries from the Power 48-5000 up.
But I am sure that also LFP cells will get better and cheaper over time.
For the most part, electric cars extend the range by putting more batteries in. They haven't significantly improved the capacity per pound.

They have improved the cost...mostly due to economy of scale but at this point, I believe, they have taken most of those advantages.

There is no new technology ready for production right now.
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Old 29-04-2020, 08:37   #1995
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Re: Oceanvolt Hybrid Motor

Hm, please check your sources, because as stated before the Renault Zoe, the BMW i3 and the Nissan Leaf have the size akku pack with much more kWh.
The Renault startet with 22kWh and is now at 52kWh, the i3 also 22kWh up to 44kWh and the leaf from 24kWh to 62kWh. All three did not change the outside dimensions of the pack. To my knowledge only Nissan changed to cell manufacturer and the cell format.
So the evolution of the NCM technology was so good to double the capacaty in less then 10 years.
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