Oceanvolt Hybrid Motor

[SV DestinyAscen]

Originally Posted by StuM

You talkin' about this:


or this:

Well played sir!

But in all seriousness neither - talking about efforts that occured nearly during the same time frame in the early 2000s by all these start ups that tried to flood the market in EU/UK with crappy electric cars.

[transmitterdan]

A 100kW induction motor has about the same efficiency at all power outputs from 20% to 120% of rated power. For a 20kW motor it's about from 30% to 120% of rated output. Really small motors have an efficiency problem at low speeds but a gear box can fix that if it matters. Usually it doesn't matter because slow speeds are not used for very long. Diesels also suffer in this scenario. Efficiency matters most at the nominal long term speed.

And for the umpteenth time, 1kW is 1kW whether produced by a diesel or an electric motor. Every time someone tries to carve out a corner case to came that 1 electric kW = 2 diesel kW they simply are not seen as being serious by people who do this kind of thing for a living. And it is a disservice to the non-technical person to make the claim.

[seandepagnier]

Originally Posted by transmitterdan

A 100kW induction motor has about the same efficiency at all power outputs from 20% to 120% of rated power. For a 20kW motor it's about from 30% to 120% of rated output.

"about the same efficiency" you basically said it can be improved this over range, if only slightly. That would be useful. Obviously "drastic improvements" are not really possible if you are already at 90%. Improvements to smaller cheaper motors that are well below 90% are possible and very interesting.

As a possible example: you might want 20kW to negotiate certain situations, but only require 2kW to cruise along at 2-3 knots (with sails helping) in very light wind for extended duration.

The 20kw motor isn't very efficient at 2kw. Maybe you have instead a 5kw motor, and use water cooling to allow it to run inefficiently at 20kw for short duration. Or you could have two motors with clutches or separate shafts. Or some day, a new type of motor that doesn't exist yet that can run efficiently down to 10% of its rating.

Really small motors have an efficiency problem at low speeds but a gear box can fix that if it matters. Usually it doesn't matter because slow speeds are not used for very long. Diesels also suffer in this scenario. Efficiency matters most at the nominal long term speed.

Slow speeds maybe used for longer periods if you are cruising on solar power.

Most motors of whatever type need to be geared down for efficiency, just because slower bigger propellers are much more efficient, and engines/motors of the same power to drive these props need to turn much faster.

Optimal efficiency has a propeller about the diameter of the beam of the boat.

Most cruising boats do not have very efficient drive systems because of other trade offs like a huge expensive propeller dragging under sail being bad, and not caring about efficiency because diesel has a ridiculous amount of energy.


To get significant improvements in efficiency (and this is nothing specific to electric propulsion) we need some kind of huge folding propellor, or an outboard with a huge propellor that can somehow be pulled out under sail... This seems more realistic for multihulls.

[tp12]

Originally Posted by cwjohm

Yes, I understand. Perhaps you could ask the moderators to allow you to start a thread on this subject, with the proviso that no dissenting opinions on the subject other that yours be allowed.

You're calling Rob out for his language yet you're perfectly happy to indulge in a ridiculous and condescending post. Consistent with your others. I think that says it all.

[motion30]

Originally Posted by transmitterdan

A 100kW induction motor has about the same efficiency at all power outputs from 20% to 120% of rated power. For a 20kW motor it's about from 30% to 120% of rated output. Really small motors have an efficiency problem at low speeds but a gear box can fix that if it matters. Usually it doesn't matter because slow speeds are not used for very long. Diesels also suffer in this scenario. Efficiency matters most at the nominal long term speed.

And for the umpteenth time, 1kW is 1kW whether produced by a diesel or an electric motor. Every time someone tries to carve out a corner case to came that 1 electric kW = 2 diesel kW they simply are not seen as being serious by people who do this kind of thing for a living. And it is a disservice to the non-technical person to make the claim.

And the fact that the matter is there is more energy in one gallon of diesel fuel than most any other source. Electric energy is a great thing but we need to regenerate that energy to replenish the batteries in the technology is just not available yet for long distances

[BigBeakie]

Just to be clear about this, everyone. All I ever wanted to do was make an educated, rational decision for our boat. I was willing to start from scratch to understand whether EP was viable for our 50' new cat, because it sounded like the benefits were well worth exploring and I had become aware of the very serious health implications of diesel fumes. That is where it started for me.

The very first thing I did, after the Torqeedo Deep Blue fiasco and that disappointment ( cost aside), was look for an alternative, and that is when I discovered Oceanvolt. Oceanvolt made the claim to me that their SD15 kW motors would give close to if not the same performance as a diesel of about 45HP (33.5kW) or double the kW rating of the SD15 kW. They based this claim on their many, many installations in a wide variety of boats. They seemed to be very quality focused and, if anything, conservative in their claims, compared to other vendors.

Did I believe this at face value? No, I did not. I really value critical thinking, and I set out to determine the truth or otherwise of this claim.

The first thing I did was ask some friends and acquaintences who happened to be, you guessed it, engineers and I heard consistently from them that it was a well established principle that electric motors could do the same amount of work as a diesel engine that was somewhere between twice and three times the kW rating of the electric. This was from mechanical engineers, in the mining industry and the timber industry, and I confirmed that this was the case in the timber industry with a site that had switched across from diesel to electric.

When I reported this on CF, I was howled down and there was much derision that a HP is a HP and Laws of Physics were being torn asunder.. well you know the story. So yes, I admit, I reacted a bit "sub-optimally" to the derision and what I perceived was a fair degree of condescension by some posters, always the same posters.

Then as things progressed, despite the obvious fact that it was I who was looking for corroborating evidence, I was accused of having "religious faith" about EP and that I was being conned by the marketing BS. Trust me, I am acutely aware of marketing BS as I had fallen for it earlier from a German vendor, which was unexpected, and highly disappointing. So I get it, there is marketing BS around. But that is what critical thinking is for.

So, now I have seen and heard 2 main pieces of evidence that I consider valid. The first is: I see Kato, a 66' cat with performance-cruising hull shapes and displacement getting a top speed of 11 knots using 30kW of power. Fact. The owner of that boat tells me face to face that in his estimation, the SD15's are the functional equivalent of 50HP diesels, which is 74.5 kW. His words, not me making it up, OK?

It MAY be true as cwjohm claims, that this boat would get the same 11 knots from a pair of 20HP diesels. But I doubt it. I definitely don't think the oars will even be close, even with Olympic athletes at the oars.

The second testimony that I thought was convincing was from a charter company that has 2 cats, one with OV SD10kW and one with 30HP diesel saildrives. They tell me they are functionally the same re performance, but the Oceanvolt electrics are saving them a fortune in maintenance costs and downtime, and the clients far prefer the electric boat for several reasons. To them, it is now a "no brainer" they said.

So, there you have it. I now have perhaps a bit thicker skin in participating on forums, so that's been a positive benefit. I have done absolutely as much as I can do to validate our decision to go Oceanvolt and their Servoprop, which I think is a game changer for cruisers.

So, have we made the wrong decision on the OV SD15 Servoprop? Do we have any buyer remorse? Nope, none, but we'll see how it goes at seas trials. I don't expect any negative surprises, from all that I have learned to this point.

[transmitterdan]

A 100kW induction motor has about the same efficiency at all power outputs from 20% to 120% of rated power. For a 20kW motor it's about from 30% to 120% of rated output. Really small motors have an efficiency problem at low speeds but a gear box can fix that if it matters. Usually it doesn't matter because slow speeds are not used for very long. Diesels also suffer in this scenario. Efficiency matters most at the nominal long term speed.

And for the umpteenth time, 1kW is 1kW whether produced by a diesel or an electric motor. Every time someone tries to carve out a corner case to came that 1 electric kW = 2 diesel kW they simply are not seen as being serious by people who do this kind of thing for a living. And it is a disservice to the non-technical person to make the claim.

[44'cruisingcat]

Originally Posted by BigBeakie

The first thing I did was ask some friends and acquaintences who happened to be, you guessed it, engineers and I heard consistently from them that it was a well established principle that electric motors could do the same amount of work as a diesel engine that was somewhere between twice and three times the kW rating of the electric. This was from mechanical engineers, in the mining industry and the timber industry, and I confirmed that this was the case in the timber industry with a site that had switched across from diesel to electric.

So if a 9.75kw diesel can run a 6 kw generator, (this exists) which can run a 6 kw electric motor, you're saying the 6 kw electric will push a boat faster than if the propeller was bolted onto the diesel? Quite a bit faster in fact?

That even with the known losses in the system, more power will be coming out than is going in?

OK, I've asked this several times, but the obvious question this raises ( obvious to me anyway) is, why not use electric motors to power generators?

[SV DestinyAscen]

Originally Posted by 44'cruisingcat

So if a 9.75kw diesel can run a 6 kw generator, (this exists) which can run a 6 kw electric motor, you're saying the 6 kw electric will push a boat faster than if the propeller was bolted onto the diesel? Quite a bit faster in fact?

That even with the known losses in the system, more power will be coming out than is going in?

OK, I've asked this several times, but the obvious question this raises ( obvious to me anyway) is, why not use electric motors to power generators?

Or skip the heavy and expensive massive battery banks. Install an electric drive unit - electrical connection only to diesel gen optimized to run at max efficiency with excess gen diverted to a more conventionally sized battery bank.

You'd think massive boatyards and marine S drive companies would eat that up. Electric connections means no need to have a hole in your hull. Can install engine with even more flexibility.

Go the diesel electric locomotive route (ignoring that pushing a hull thru water isn't like moving a train).

[BigBeakie]

Originally Posted by 44'cruisingcat

So if a 9.75kw diesel can run a 6 kw generator, (this exists) which can run a 6 kw electric motor, you're saying the 6 kw electric will push a boat faster than if the propeller was bolted onto the diesel? Quite a bit faster in fact?

That even with the known losses in the system, more power will be coming out than is going in?

OK, I've asked this several times, but the obvious question this raises ( obvious to me anyway) is, why not use electric motors to power generators?

Ok, I'll bite. But first, a question back to your question. Is your 9.75kW diesel running at it's peak power to produce those 6kW of output power from the generator? I assume so. So in reality, that 9.75kW diesel will be running at about .75 of it's maximum rated output, and be producing proportionately less power output. Right?

So, who runs ICE engines at peak power for extended periods? Why would you do that if you wanted them to last? They are not designed to do that. They are damaged by doing that.

By contrast, you can run an electric motor at it's rated maximum output for effectively, forever.

Summary statement: A diesel running at it's maximum output will, of course, put out more power than an electric motor rated at one half of the kW output of the diesel, and the more "powerful" diesel will push the boat a BIT faster. But if you take the time to look at boatspeed vs water resistance vs power required curves, you will see that to get very little more speed, you need massive amounts of additional power. And yes, a much bigger diesel engine can supply that extra power IF YOU WANT TO FLOG IT AT WOT !


But we don't want to do that to our diesels, or in your case petrol outboards ( which are even worse) that we rely on, do we?


As to your question about using an electric motor to power a generator, if you are asking the question seriously, then it seems you've missed the plot. But in fact, this is exactly what was done in the past, before electronics took care of frequency control. A ships diesel generator would produce the general house loads ( generally DC), but it would also power an electric motor that would drive another generator that would produce specific AC or DC voltages and/or frequencies for specific applications.

[BigBeakie]

This is why you don't want to run an ICE at WOT for too long.....

https://www.youtube.com/watch?v=RUquK_6WIjk

[44'cruisingcat]

UThe generator I'm talking about has a 13 HP diesel, and is rated at 6 kw continuous. This is to military specification.

As to your other comments, re outboard motors, your opinion, not supported by facts. Who runs outboards at WOT almost all the time? Just about every houseboat charter operator. On the couple of times I've hired a houseboat, the instructions have been " both motors full throttle all the time. Or you won't be able to steer."

These operators expect to onsell these motors at 5000 hours.

But that's just another of your diversions.

You seem to be constantly shifting the goalposts in your equivalency claims. Not long ago it was that 15 kw electric motors matched 55 kw diesels. Now it's that they match those diesels, as long as you never run them at full throttle.

A meaningless claim, like saying a corolla has the same performance as a Porsche, as long as the Porsche is always driven slowly....

[BigBeakie]

Originally Posted by 44'cruisingcat

UThe generator I'm talking about has a 13 HP diesel, and is rated at 6 kw continuous. This is to military specification.

As to your other comments, re outboard motors, your opinion, not supported by facts. Who runs outboards at WOT almost all the time? Just about every houseboat charter operator. On the couple of times I've hired a houseboat, the instructions have been " both motors full throttle all the time. Or you won't be able to steer."

These operators expect to onsell these motors at 5000 hours.

But that's just another of your diversions.

You seem to be constantly shifting the goalposts in your equivalency claims. Not long ago it was that 15 kw electric motors matched 55 kw diesels. Now it's that they match those diesels, as long as you never run them at full throttle.

A meaningless claim, like saying a corolla has the same performance as a Porsche, as long as the Porsche is always driven slowly....

To remind you what I said on page 67 post #997 of this thread, which you refer to;

"On Kato with the SD15 and Gori props, he got 10 knots at max power under exactly same conditions. Yes, that is correct. With 2 x 15kW electrics he got 1.3 knots less top speed than 2 x 56kW Yanmar diesels at WOT. "

What I was saying from my discussion with Tony, was that the SD15 at max power were close to the 56kW Yanmars at max power. I did not say they "matched" the diesels (your words), or that they produced exactly the same boatspeed at WOT. There is no goalpost shifting going on, just read what has been said and don't put your own spin on things.

And then I said that with the prop upgrade he was getting 11 knots with the OV Sd15's, which is very close to Kato's Yanmar testing. You have commented that they got more like 15 knots, but that was not Tony's comment, so let's say it was somewhere in between 11.5 and 13, OK? I think that is realistic. The point is, it takes diesels that are significantly more powerful, AT WOT, to get the extra .5 to 2 knot difference. That is my point. That has always been my point. Do I have to say it some other way for you to understand that?

Some, like myself, do not care about going 1 to 2 knots faster at full power, couldn't care less. Just wastes fuel as far as I'm concerned. For for those folks, all I'm saying is that electric is a viable alternative with some significant benefits.

By far, BY FAR, the most time motoring on electric will be based on power from the batteries that is harvested from solar. Over and over again. The cost of the solar panels will be paid for by the savings in diesel fuel and maintenance. And the squirts of full power when needed will, by far, be short duration events well within the battery capacity of an LFP bank. Only when we need to motor for extended periods such as when becalmed, will the genset be required. If we are sailing, we are generating significant power via regen.

The goalposts remain firmly in place.

However, you are correct that SOME ICE are ok with operating at WOT, if they are built for that application. I'll take your word for it that outboards fit that description, and obviously small aircraft engines are another example. Marine diesels are not, as far as I understand.

[44'cruisingcat]

OK, if comparing a shorter, heavier boat against a longer lighter one, and then fudging the numbers is your idea of evidence, you win. Electric motors are equal to diesels of three times the output. But they still use diesels to run generators. Strange.

[44'cruisingcat]

BTW, You may need to learn to like running at WOT......