Using electric motors instead of Diesel on your cat

[Beccara]

Just to jump in here,

Electric motor's normally have all their HP available at any RPM, ICE motor's normally only have a % of their HP available at anything but peak RPM. Therefor if the boat is being pushed at the ideal speed at only %50 of peak RPM then all you need is a electric motor to 50% of HP, If you need/want to go above ideal speed for any amount of time then you look for a motor able to be overloaded by x% for y minutes.

To give you an idea of this look to high pressure pumps,

A 10GPM 2000PSI CAT pump wants a 18HP ICE Motor,
A 10.5GPPM 2000PSI Cat pump wants 14.4hp Electric.


To say that a 20HP ICE motor must be replaced with a 20HP Electric motor because A HP=HP is to ignore the basic differences between the equipment involved.

As to why Yanmar and co aren't doing this? This is technology now, Not marine - Let the DIY'ers have a crack at it, find out the failings and then adapt it to your products

[cwjohm]

Maybe I've left something out, if so, let me know

I have just come back from China. I have four engineers over there working through issues on a new product that uses proven technology that was meant to be ready in July but hopefully will now be ready end of February.

I am consulting on a court case over an electromechanical system that was theoretically working in the laboratory, but took another 4 years to get working in the field and another ten years to get reliably working in the field.

In 35 years leading design teams I have invariably heard the idealogues all with impeccable engineering pedigrees tell me that on the basis of calculations and spread sheets that products will work in a certain time and I am still waiting for this to materialise.

When Volvo released the sail drive which was based on proven technology there were many early adopters who suffered, so much so that it earned the label "the green death". The numbers you quote in regard to diesels are evidentiary of this even though they are completely misleading in regard to modern diesel marine drive systems.

Even assuming everything you say is correct, which I would dispute, as would many others, then the transition from technological innovation to working product will take a good 5-10 years.

Then we need to consider that this innovation is for the marine industry where you rely on it in situations where your life may be in jeopardy. Evidence the GB55 where even the input of many millions of $ failed to prevent a poor outcome.

In summary, what you have missed is that you believe that a significant degree of research will make up for a significant lack of hard testing of the product in the field over a long period. You are prepared to be the guy who tests the beta prototypes and you are prepared to put your safety on the line to do so. As an individual I have a significant tolerance to risk, but plainly, yours is even significantly higher again.

[Beccara]

If tech took 5-10 years from idea to product the internet and electronic's industry wouldn't exist. Both of which have major public safety components and save lives every day

The Airbus A380 took less than 10 years from design to first handover and that invovled creating new tech, A Electric boat is off the shelf components - The secret sauce is the glue to hold it all together

[Stumble]

God not this again...

This has been discussed ad nausium... If you undersize an electric motor by 50% then you will wind up with a motor with 50% the power available. It's just that simple. Most of the time it really won't matter, and since electric boats typically spec cruising speeds much lower than a diesel it doesn't matter much, since the diesel would only be putting out a fraction of its max hp anyway. But in an adverse wind, or waves the boat won't have the power to maintain speed.

As for prop size... It is true that a larger prop will help efficiency somewhat, but the problem is that you have to find a spot for that larger prop. Generally speaking a 16" prop returns about 30% efficency. Doubling the prop size will increase that efficency by about 30%. So when you switch to a 32" prop you get 40% efficency. Of course you now have to find somewhere to swing a wheel that big.

Compounding this is the fact that clearance distances are dictated by the size of the wheel, so if you need 17% of the diameter with a 16" prop (2.72 inches) you now need 5.44 inches for the larger wheel. So for that relatively small efficiency gain you went from needing 18.75" of clearance to 37.5" of clearance.

On a sail boat you also have to drag around a massive prop all the time while sailing. And let's not consider the cost involved in dropping the shaft an additional 20 inches, since the 32" prop alone will set you back about $5,000 more than a 16".

Frankly this is just silly. Electric conversions work fine if you accept and live within their limitations (minimal range, and slower speeds). But trying to do a conversion to full electric for a long range cruiser just doesn't work. At least not without installing a diesel generator the same size (or close) as the propulsion motor you are pulling out.

[Beccara]

Originally Posted by Stumble

God not this again...

This guy gets it

[cwjohm]

What a load of rubbish. Electronics started with silicon doping invented in the 1950s and the internet started in the 1970's.

Were you not around for the dot com boom where supposedly all of these great innovations on the internet crashed and burned. It is only in the last five years, nearly 10-15 years after the ideas were first raised that the actual results have been seen in terms of commercial success. How long did it take for Microsoft to get an operating system that was reliable. Over ten years.

Yes, software now has a faster turnaround time, and electronic innovations like mobile phones are much quicker, but we are talking billions in R&D commensurate with market demand.

The Airbus was based on design elements that go back 20-30 years. To say that it went from first design to handover in ten years is just wrong.

To state that an electrically propelled boat is based on off the shelf components is again wrong. In any complex electromechanical system involving mechanical drives, electrical systems, electronics, software, and battery technologies there are several areas of innovation that link these elements together. Sure, as with anything you can cobble something together but it does not constitute a properly developed product that will reflect reasonable levels of reliability.

[cwjohm]

Frankly this is just silly. Electric conversions work fine if you accept and
live within their limitations (minimal range, and slower speeds). But trying to
do a conversion to full electric for a long range cruiser just doesn't work. At
least not without installing a diesel generator the same size (or
close) as the propulsion motor you are
pulling out.

Yes, what will now happen is that hybrid technologies will improve such that in 5 years time the motor and the generator will be seen as an integral unit and over 10-15 years battery technologies and their integration into the hybrid improving to such an extent that the fuel driven technologies as we understand it will become obsolete. It will be a natural technological progression.

[Beccara]

Originally Posted by cwjohm

What a load of rubbish. Electronics started with silicon doping invented in the 1950s and the internet started in the 1970's.

Were you not around for the dot com boom where supposedly all of these great innovations on the internet crashed and burned. It is only in the last five years, nearly 10-15 years after the ideas were first raised that the actual results have been seen in terms of commercial success. How long did it take for Microsoft to get an operating system that was reliable. Over ten years.

Yes, software now has a faster turnaround time, and electronic innovations like mobile phones are much quicker, but we are talking billions in R&D commensurate with market demand.

The Airbus was based on design elements that go back 20-30 years. To say that it went from first design to handover in ten years is just wrong.

To state that an electrically propelled boat is based on off the shelf components is again wrong. In any complex electromechanical system involving mechanical drives, electrical systems, electronics, software, and battery technologies there are several areas of innovation that link these elements together. Sure, as with anything you can cobble something together but it does not constitute a properly developed product that will reflect reasonable levels of reliability.

Yes things are built on the foundations of what comes before, You could say the electric motor and LiFePo4 batteries are built on elements that at 50-100 years old. Likewise all planes have design elements going back 100 years. The actual "Lets build a x Passenger plane" to the delivery of serial #1 is much shorter tho.

[BigBeakie]

Chris,

For your last 2 posts, thank you.

I appreciate them. I am not a technology ideologue, in fact I'm quite conservative in that respect, so I do appreciate your input from the perspective of someone experienced in this matter. You are correct, the reliability issue of EP is the area to focus on at this stage of it's lifecycle. That's why I have tried to focus on it. But there is no substitute for real world operational hours to prove the solution, you are quite correct.

Your responses were cogent, and well meaning, and on my part, duly noted.

I also have been at sea (Coral & Tasman) in cruising cat under very adverse conditions, so I have a more than healthy respect & appreciation for the realistic risks. But the boats sailing ability and skipper's experience got us through 2 days of nail biting, not the engines. I'm not sure that engines are the panacea for dealing with dangerous situations, compared to seamanship generally, with some notable exceptions of course.

[BigBeakie]

Originally Posted by Stumble

God not this again...

This has been discussed ad nausium... If you undersize an electric motor by 50% then you will wind up with a motor with 50% the power available. It's just that simple. Most of the time it really won't matter, and since electric boats typically spec cruising speeds much lower than a diesel it doesn't matter much, since the diesel would only be putting out a fraction of its max hp anyway. But in an adverse wind, or waves the boat won't have the power to maintain speed.

As for prop size... It is true that a larger prop will help efficiency somewhat, but the problem is that you have to find a spot for that larger prop. Generally speaking a 16" prop returns about 30% efficency. Doubling the prop size will increase that efficency by about 30%. So when you switch to a 32" prop you get 40% efficency. Of course you now have to find somewhere to swing a wheel that big.

Compounding this is the fact that clearance distances are dictated by the size of the wheel, so if you need 17% of the diameter with a 16" prop (2.72 inches) you now need 5.44 inches for the larger wheel. So for that relatively small efficiency gain you went from needing 18.75" of clearance to 37.5" of clearance.

On a sail boat you also have to drag around a massive prop all the time while sailing. And let's not consider the cost involved in dropping the shaft an additional 20 inches, since the 32" prop alone will set you back about $5,000 more than a 16".

Frankly this is just silly. Electric conversions work fine if you accept and live within their limitations (minimal range, and slower speeds). But trying to do a conversion to full electric for a long range cruiser just doesn't work. At least not without installing a diesel generator the same size (or close) as the propulsion motor you are pulling out.

Stumble,

Here we go again, more FUD More fear, uncertainty and doubt!

There seems to be, perhaps, a failure of critical thinking in your post.

Who said anything about doubling the size of the prop? What nonsense! Why not make it a 4 foot diameter prop in your example, that would make your case even stronger...

Who said anyone, let alone a multihull sailor, would contemplate dragging around a 32" fixed blade prop? What nonsense! There are alternatives, but you knew that...

Who says you need to have a 40HP generator to charge batteries? What nonsense!

Same old strawman debating technique used by those with weak arguments, ie. depict the idea you wish to discredit in the worst possible light, even though it is irrational.

[Stumble]

Originally Posted by BigBeakie

Stumble,

Here we go again, more FUD More fear, uncertainty and doubt!

There seems to be, perhaps, a failure of critical thinking in your post.

Who said anything about doubling the size of the prop? What nonsense! Why not make it a 4 foot diameter prop in your example, that would make your case even stronger...

Who said anyone, let alone a multihull sailor, would contemplate dragging around a 32" fixed blade prop? What nonsense! There are alternatives, but you knew that...

Who says you need to have a 40HP generator to charge batteries? What nonsense!

Same old strawman debating technique used by those with weak arguments, ie. depict the idea you wish to discredit in the worst possible light, even though it is irrational.

Originally Posted by BigBeakie

Stumble,

Here we go again, more FUD More fear, uncertainty and doubt!

There seems to be, perhaps, a failure of critical thinking in your post.

Who said anything about doubling the size of the prop? What nonsense! Why not make it a 4 foot diameter prop in your example, that would make your case even stronger...

Who said anyone, let alone a multihull sailor, would contemplate dragging around a 32" fixed blade prop? What nonsense! There are alternatives, but you knew that...

Who says you need to have a 40HP generator to charge batteries? What nonsense!

Same old strawman debating technique used by those with weak arguments, ie. depict the idea you wish to discredit in the worst possible light, even though it is irrational.

My point wasn't that anyone should use a prop that big, but to point out how silly it is to assume that using a larger slower turning prop will result in efficancy gains. It's an easy statement to make, and is true, but I larger slow prop has to be enormous to make any real difference.

And no you don't need a 40hp generator to charge batteries. But you do need a 40hp generator to power 40hp drive motors. You can't carry enough batteries to give electric propulsion sufficient range for much beyond entering and exiting the harbor.

The reality of this is that electric propulsion is just a silly idea and pretty much always will be for cruisers. Since you will still have to carry power in the form of diesel to power the electric motors. Sure there are people who are doing it anyway, there are also people who go cruising without engines. But most people will never fit that demographic.

The fundamental problem isn't technology, it's energy density. And effective storage of electricity hasn't changed much in 100 years. The best battery in the world frankly is orders of magnitude worse at storing energy than diesel.


Finally, this has nothing to do with FUD. I have owned an electric boat, and I have watched the conversions of others. For a small subset of people they do work, and work well. But suggesting that those systems will work for most or even many people is just wrong. Before building a system you need to ensure it works on paper, and for now electric propulsion doesn't even work on paper except for a very small set of sailors, and even fewer cruisers.

[BigBeakie]

Originally Posted by Stumble

My point wasn't that anyone should use a prop that big, but to point out how silly it is to assume that using a larger slower turning prop will result in efficancy gains. It's an easy statement to make, and is true, but I larger slow prop has to be enormous to make any real difference.

And no you don't need a 40hp generator to charge batteries. But you do need a 40hp generator to power 40hp drive motors. You can't carry enough batteries to give electric propulsion sufficient range for much beyond entering and exiting the harbor.

The reality of this is that electric propulsion is just a silly idea and pretty much always will be for cruisers. Since you will still have to carry power in the form of diesel to power the electric motors. Sure there are people who are doing it anyway, there are also people who go cruising without engines. But most people will never fit that demographic.

The fundamental problem isn't technology, it's energy density. And effective storage of electricity hasn't changed much in 100 years. The best battery in the world frankly is orders of magnitude worse at storing energy than diesel.


Finally, this has nothing to do with FUD. I have owned an electric boat, and I have watched the conversions of others. For a small subset of people they do work, and work well. But suggesting that those systems will work for most or even many people is just wrong. Before building a system you need to ensure it works on paper, and for now electric propulsion doesn't even work on paper except for a very small set of sailors, and even fewer cruisers.

Greg, look I am no expert in propulsion, and I'm not an engineer, of any description. So don't believe me. Read what Nigel Calder has written recently, he's been studying and exhaustively testing electric hybrid, both parallel and series, for several years. He's the one who knows what he's talking about. Can we agree at least on that? Or are you setting yourself up as an expert to challenge Calder's data?

FYI, it is entirely feasible to run a serial electric system on a cat by alternating motors for continuous motoring while the other side charges.
Why are you assuming you run the motors directly from the generator? That's not the way to go because of likely damage to the motors (if they are modern efficient type), the batteries should be a "buffer", or a fuel tank. You give the impression you have not read other posts in this thread, such as #29 where I say Because at some point you will need to, or rather choose to, motor for extended periods when becalmed. So with a system that has 2 motors and a dedicated propulsion battery for each motor, you can motor off battery with one while you are charging the other battery with the generator, and keep switching back and forth.

And Calder also states that big slow turning props are the way to go for EP due to the torque characteristics of EP. You disagree with Calder? Ok fair enough, why? Show us your kW input, kw output thrust, rpm, prop size & pitch data. I await it eagerly, and you'll gain real kudos in the industry for taking on Calder and proving him "totally silly".

And on the matter of efficiency and energy density, sorry to say it, but yes that is FUD. Of course fossil fuels are energy dense, and much more so than batteries, that's bleeding obvious, but, so what? Most EP motoring events (by number) will be on battery, which is re-charged by an adequate solar array. And in the times when you are becalmed and need to motor for longer than the batteries can provide, then start the gennie and motor continuously until the wind picks up again.

Efficiency comes back to getting the most amount of work out of the resources you use, doesn't it? Energy in vs energy out. And usually we are concerned about it, as consumers, because the energy in costs us money, like when you refill a big tank of diesel. But if diesel were free, would you be so concerned about whether your motor was running "efficiently"??? Of course not. When petrol was cheap as anything, Detroit didn't give a damn about engine "efficiency", and neither did their customers. Things have changed a bit, haven't they?

So, what is more "efficient" than filling your battery fuel tank with sunshine, my friend? Over and over again. Do I care that I may be wasting some sunshine fuel, compared to another technology that is super energy dense? Not really, because after the initial expenditure on panels, I'm filling up for free.

Can I ask, specifically which part of this doesn't make sense to you?

[seandepagnier]

Originally Posted by valhalla360

So by your wattage estimates, a cheap trolling motor will give you 3kts?

Yes using two cheap motors, one is 25lb, the other 50lb thrust I achieve 3 knots. The issue here is the 60 amp current draw at 12 volts.

A more efficient electric drive will use less than half the power for the same power consumption.

There is nothing more fuel efficient than sailing.

Also using tidal currents.

Originally Posted by valhalla360

If its all about turning a big prop, just add a deeper reduction gear on the transmission and you achieve the same thing.

Sorry but you aren't getting double the thrust for the same HP just because you turn a slightly larger prop.

Not slightly. Much larger. You may triple the diameter of the propeller to get double the thrust with equal power input, and this only makes sense for the slower more efficient speeds you will be going for longer duration. In other words, half hull speed or lower.



If you think electric doesn't have range, well that just isn't true. Consider the japanese guy who crossed the pacific 20 years ago using solar panels and flooded lead acid. Then the boat that circumnavigated average 11 knots of speed day and night using solar power. I myself have motored day and night using electric propulsion at 2-3 knot speeds. I have only used solar panels for a power source.

About torqeedo... they design their products to recharge on a dock, not to run on solar power. This is a fact and you should consider this when evaluating what they have. You will also find you can build a more efficient custom unit for a fraction of the price.

[BigBeakie]

[IAbout torqeedo... they design their products to recharge on a dock, not to run on solar power. This is a fact and you should consider this when evaluating what they have. You will also find you can build a more efficient custom unit for a fraction of the price.]"[/I]

Not true, it is not a fact. The Deep Blue controller can input shore power, solar & generator. And their hybrid system can take any input including regeneration.
I'm not as familiar with their little outboard product range, but they also can take solar input, as least some of them.

I have checked as many vendors as I can, and Torqeedo is the most efficient motor (54%, input kW to output kW) that I could find and they publish the figures, unlike other vendors who do not publish any tested efficiency data.

I would be happy to learn of others with comparable tested efficiency, what are they?

[cwjohm]

Calder is quite clear on the issue of Hybrids after testing for five years in that he states that they are not more efficient than conventional diesels.

For an alternative view see

The Science of Hybrid Propulsion: The Great Debate | | PassageMaker

As I see it the problem with the comparative densities of diesel vs battery is that you have to jump through extensive technical hoops to make a battery based system viable. Yes of course you gain the benefit of using solar capacity on motoring but the average cruiser does not have significant solar capacity left over after other uses. Loading up with the required solar arrays (many KW) and batteries (many kw) means significant additional weight. Further the complexity of separate battery systems and charging regimes makes for a very complex system.

What will make this viable for the average cruiser is firstly the incorporation of the generator into the motor and secondly an order of magnitude increase in energy density of batteries.

I do agree with the point made by someone here that mostly this is a matter of stepwise evolution, although I think there are some quantum leaps to be made in battery technology.