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Old 17-02-2020, 12:26   #136
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Re: Jimmy Cornell goes Electric, with a Cat

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Originally Posted by GrowleyMonster View Post
Is that 3kW max, peak, or sustained power?
It's just the hull resistance curve.
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Old 17-02-2020, 13:36   #137
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Re: Jimmy Cornell goes Electric, with a Cat

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yeah cos theres no emissions expelled in building the boat is there???

sorry but this is just yet more hypocritical virtue signalling

the least emissions path by far would be to NOT BUILD ANOTHER NEW BOAT and make do with an existing one.
Thatís a silly thing to say. We all have to reduce our carbon footprint and no one knows that better than those exposed to the elements? At this point we canít totally eliminate emissions but a responsible sailor will do what he can.
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Old 17-02-2020, 14:10   #138
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Re: Jimmy Cornell goes Electric, with a Cat

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Very interesting news from Jimmy Cornell:

His next boat is an Outremer 45 and it will be all electric, ZERO FOSSIL FUELS
Cool!

I first wondered why he is not going for the Aluminum version of the O45 (the Allures 47.9) but meanwhile his choice makes perfectly sense to me.

Zero fossil fuels means you need maximum efficiency. This is the reason for a cat. And a light carbon design is certainly much more efficient (better hull resistance curve) than an aluminum design.
I guess he will combine this with the ultimate hydrogeneration feature from Oceanvolt, featuring adjustable pitch and generating enormous amounts of energy while sailing. Maximum solar power is certainly a must have.
Accidentally I have the specific shaft power need of the extended Outremer 45 at hand - it is just 3 kW total shaft power (2x1.5) for a speed of 5 kts: Very good choice, Mr Cornell!
Better to have no engines if you so worried about the little bit of emissions.

Maybe cut down on electric gadgets as well
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Old 17-02-2020, 15:08   #139
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Re: Jimmy Cornell goes Electric, with a Cat

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Very unrealistic thinking here. Itís as if you are proposing not making anything new. Man started polluting the earth the moment he discovered fire. Iím all for ecology but letís try and keep it real.
Agree with the pollution but in certain cases itís necessary to see in the long term what can be done to go more eco
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Old 17-02-2020, 15:27   #140
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Re: Jimmy Cornell goes Electric, with a Cat

Didn't Lagoon build an electric CAT some years ago?

According to my calculations, 7.1kw is only 10hp.

https://www.kwtohp.net/hp-to-kw-conversion

That might be enough for a very small cat with limited windage, but my 47' CAT has 2 x 40hp Yanmars and in 30kts of wind is under powered when trying to maneuver.
How do you generate 7kw of power? I believe it would take days to generate enough power with solar for just one hour of run time.

I think the answer might be to build recharging stations outside every harbor
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Old 17-02-2020, 16:59   #141
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Re: Jimmy Cornell goes Electric, with a Cat

Regardless of whether or not Cornell bought it with his own money or was gifted by vendors looking for publicity, regardless of whether or not the environmental impacts of it's construction are better or worse than the fuel he would have burned otherwise, and regardless of whether or not you feel "all-electric" is there yet, or even if this is even ahead of other examples, this is absolutely another technological step. It is the kind of demonstration we need to check point the technology at this point in time. It is the kind of demonstration we need to measure our progress toward a fossil free future for cruising.

It is no reason to bring out the knives.

Me, I don't think it is there yet in absolute terms. It does not seem up to the task for what I do with my cruising yacht. For others, it may be entirely suitable. And of course there is the business case. The batteries alone are worth more than my whole boat.

But more power to him. Get it out there. Once the hype dies down maybe we'll hear how it actually works, like 5-10 years in.

I do however have a beef with the promoters of regeneration. It is dishonest to claim that current regen systems can supply enough KW to recharge a battery for a boat under sail. 8 Knots? There are certainly boats which can do eight knots, but how often? And for how long? And if you drag along two big enough regen props to create that much power it isn't likely to be going 8 knots any more unless the wind is really up and the boat is totally powered up under sail; How often do we do that and how many of us have those type of boats? It is an unrealistic claim and they know it. But maybe it sells regen units to electric wannabe's who live on hopes and wishes rather than science.

As for the rest of us who have modest boats and who don't have $40,000 to invest in a whole new engineering solution only to be limited to 3-5 hours of slow motoring, let's just keep running our old diesels and watch the developments of this new technology, from afar. Someday it will be ready and practical.

And most of all, let's chill.
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Old 17-02-2020, 17:44   #142
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Re: Jimmy Cornell goes Electric, with a Cat

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Originally Posted by mglonnro View Post
The Outremer 4E is actually a version of the 4X, so 48' of goodness! And somewhere between 8.2 - 11.7 t of displacement and 2 x 30hp for the specification version.

Comparing to what Oceanvolt has done before with roughly similarly sized catamarans, 2 x 15kW seems like a probable alternative. At least it is my uneducated guess
2 x 15kW is certainly not excessive. For the same speed, there will not be much additional power consumed. The reserve power sooner or later will be welcome.
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Old 17-02-2020, 19:15   #143
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Re: Jimmy Cornell goes Electric, with a Cat

Every time the subject of electric power comes up, the same issues are brought out.


The fans talk about how you need a small fraction of the diesel HP, regeneration, solar, not being in a hurry, learning to sail more, waiting for the wind, never needing to motor to windward (that's why you have sails), the glorious quiet, etc. There are lots of fans that rave about how good it is, and there are even a few fans talking about how they have already begun the changeover.


The naysayers (I'm one) talk about needing to be home on Sunday evening, needing to motor two days in a row (a windless weekend with a party somewhere, or the end of a longer cruise, etc). Or looking at how long it takes for the ROI on a boat that is motored less than 100 hours per year (the electric argument almost requires that you be someone who doesn't motor much!). Or the steep cost of replacing batteries when they die (or are murdered).


But what is missing is the input from active cruisers who have finished the conversion. The weekend sailors who sail 30 miles to an anchorage on Saturday, and motor home on Sunday. Or have a 5 mile slog to weather in 20 gusting to 30 in a channel not well suited to beating (we have lots of them here on the Chesapeake). Or more adventurous types who meander down the ICW. I'd love to end the philosophical debate about theoretical differences in diesel vs electric HP, or views on how a boat should be sailed, and hear stories from those how have completed it. Where are they? I do have a friend who had electric on a 43' distance cruiser, but it has been replaced with a diesel engine.



I did just do an interesting Yachworld search. Global, no country limits, no cost limits, no year limits, on boats from 35-45 feet, listed as "electric propulsion" (There is a search criteria for engine type). There are 10. Of those, 5 are labeled wrong or clearly day sailors. So globally, there are 5 electric powered cruising sailboats between 35 and 45 feet for sale. Interesting. And one of those is very comparable to what Jimmy is having built.
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Old 17-02-2020, 22:44   #144
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Re: Jimmy Cornell goes Electric, with a Cat

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So beware of the exponential thing the wind generator salesmen played with. "This generator puts out 400 watts" they would say - only for you to find out that you need to be in 28 knots - all day - to get that. Back where we anchor and the wind drops to 12-15 the power output plummets. Its an exponential thing - the kinetic energy of any fluid - wind or water - goes up by the square. So going at 7 knots you produce 49 units of energy, 8 knots 64 units and 12 knots 144 units. So you can see why Electrovolt give you the 12 knot reading. There is double the energy of the more achievable 8 knots.

Then they reverse the shell game to say - and you can now motor for hours, because they use the squared relationship to allow the low power output to give some longer times under power by going slow. Faster than reasonably achievable speeds under sail and lower than wanted speeds under motor. You shouldn't be able to have it both ways.

I will be very happy to see someone who is not company based, put all the figures together after a year of sailing with such a set up. I am dubious about the claims because it does not gel with the reality of my sailing. (Average speed under sail after a few thousand miles coastal - 7.5-8. Average motor speed 7) But data is king and I will always change my mind when shown data that shows me wrong. Until then I will sit stay with internal combustion, on the boat at least.

Phil
Phil,

I very much appreciate your desire to be mindful of the actual physics involved and have been doing my best to adhere to real numbers (not just the vendor's claims). But I don't think it completely disingenuous of them to highlight the best of each side of the equation (propulsion speed/power and regen); I consider such estimates the same way I consider EPA milage estimates for cars. Most people don't consider the EPA malignant when they don't achieve those numbers, but there are a few "hyper-milers" which exceed those estimates lending them some creditability.

For my Athena 38 which had 2 x 2GM20F engines that are rated at 11.8kW at 3400 rpm, let's assume they make 0 watts at idle (800rpm) giving us a useful power band of 2600rpm. If I assume (for simplicity's sake) that the power/RPM curve is linear (which is a bit optimistic), I know that on my boat with clean hulls and pretty crappy low profile 2-blade props I could motor at 5kts in calm water at ~2200rpm, or roughly 45% of 11.8kW = 5.31kW (times 2 engines). There are a lot of losses in this drivetrain, both within the engine itself and through the saildrive, so perhaps 70-80% would be considered generous through the SD20 bringing the total at the prop of closer to 4kW. According to some online resources, there's a 30% efficiency improvement between 2 and 3 blade props so we're now down to around 2.8kW per motor via direct POD drive into a 3-blade propellor to provide the same performance at slow cruising that we do to get into and out of a marina to sail. The last thing to note is that my engines had around 3000 hours on them and were likely not producing the power or compression they did when new, so I'm going to guess closer to 85% of original bringing the total needed electric power below 5kW (<2.5kW per motor) to cruise at 5kts in calm water.

With only a 10.6kWr battery I'm looking at less than 2 hours of motoring time or ~10miles, but that pack only weighs 110lbs and I'm anticipating adding a lot more to it as I develop a better understanding of the performance characteristics. If I reduce speed to 4kts I probably come close to doubling my range.

As for electric component efficiency (concern mentioned in previous post), Li-Ion batteries have a coulombic efficiency (full cycle) of 99.5%, modern brushless DC motors regularly produce 95%, the KLS-H Kelly controllers claim 99%, wire of sufficient gage/length ratio is generally nearly 100% and the POD drives are direct drive with no gearbox losses. In my particular case, my drives are also out of the water when sailing (with no regen) as they're retractable allowing for very aggressive, high surface area props that would be far too lossy on a saildrive leg when sailing.

I'm also aware of the various biases I've developed and trying to condition my expectations to allow for the possibility that I'm off by nearly a factor of 2 in the above calculations, and while this would be a bit disappointing, it has still not dissuaded me from performing the conversion; the advantages are just still too overwhelming in my case (forced refit).

If I recall your earliest post in this thread you mentioned that you wanted to be able to maintain 7kts of speed over 100 (or was it 150?) miles and thus electric propulsion wasn't there yet; without rehashing what I'm sure you're already aware of regarding the ability to match that performance with a series hybrid of sufficient generator capacity, I think of this threshold as being quite fuzzy and dynamic and very different from sailor to sailor. It's also a moving target with rapidly advancing battery tech. Perhaps most cruisers are more in your camp right now and those like me are still a minority, it is nonetheless not a binary thing; many may reconsider their requirements and performance thresholds (not to mention their own preferences) as they gain exposure (from bleeding edge neighbors ;-) of the many other possibilities electric propulsion bring. Silent propulsion can be truly intoxicating in it's own right, and going fully fossil-free in all boat systems is the height of simplicity in some respects.

Regardless, thanks for applying a healthy, physics based reality check (skepticism?) to the discussion. Electric propulsion doesn't win any converts if it's too much hype and not enough raw data. I hope to be able to supply some of the latter in the coming months (motor 1 installed!!, motor 2 on it's way).
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Old 17-02-2020, 23:04   #145
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Re: Jimmy Cornell goes Electric, with a Cat

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Originally Posted by wingssail View Post
I do however have a beef with the promoters of regeneration. It is dishonest to claim that current regen systems can supply enough KW to recharge a battery for a boat under sail. 8 Knots? There are certainly boats which can do eight knots, but how often? And for how long? And if you drag along two big enough regen props to create that much power it isn't likely to be going 8 knots any more unless the wind is really up and the boat is totally powered up under sail; How often do we do that and how many of us have those type of boats? It is an unrealistic claim and they know it. But maybe it sells regen units to electric wannabe's who live on hopes and wishes rather than science.
I agree there's a lot of potential amplification (wishful thinking?) when discussing regen, but this is also an area most significantly improved recently with the adoption of better motor controllers (pure sinusoidal) and motors (brushless DC POD drives with no gearboxes). Also, larger motors (for a given application) will have more efficient regen, so one should tend toward larger motors if one wants to improve not just peak power but also regen efficiency. Finally, regen is not a static thing; just like governors (well, sort of...), one can determine how much drag one wants to add at any given boat speed and extract only as much power as they're willing to tolerate in terms of performance penalty, all via the turn of a knob. The slower shaft speeds possible with some electric drives also allows for larger more efficient props that regen sooner (4-5kts vs. 8kts); the ones I've got are supposed to provide 1.2kw at 8kts (from a 7.1kW POD drive) with a big 3-blade prop. I'm hoping that still means I can get 300-500W at 5kts, but here in the SF Bay I'm almost always single of even double reefed with frequent 20-25kt winds and 10kts isn't uncommon in our FP Athena 38 cat even with tired 25 year old sails.
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Old 17-02-2020, 23:21   #146
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Re: Jimmy Cornell goes Electric, with a Cat

Ah!

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The new Outremer 4E is based on a mixture of features taken from the Outremer 45 and 4X, but with several modifications. Many of the building features will ensure that the result will be a light boat, ideally around 9 tons. As in the case of my Garcia Exploration concept, I am aiming at a comfortable, easy to sail boat by a short-handed crew.

Propulsion and regeneration will be provided by two electric saildrives rated at 15 kW each and developed by the Finnish company Oceanvolt. The system has been well tested and will meet my expectations of ample and reliable energy regeneration under sail.
https://cornellsailing.com/2020/01/t...e-is-electric/

Quote:
The show was also a suitable venue for the signing of a long-term agreement between the builders Outremer and Oceanvolt, who will supply the electric propulsion system.
https://cornellsailing.com/2020/01/t...ogress-report/

Long-term agreement sounds good
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Old 17-02-2020, 23:50   #147
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Thumbs up Re: Jimmy Cornell goes Electric, with a Cat

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Very interesting news from Jimmy Cornell:

His next boat is an Outremer 45 and it will be all electric, ZERO FOSSIL FUELS
Cool!
Very interesting indeed. I look forward to his reports. Not having to deal with a smelly, high-maintenance and noisy diesel engine will be very welcome.
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Old 18-02-2020, 02:18   #148
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Re: Jimmy Cornell goes Electric, with a Cat

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But what is missing is the input from active cruisers who have finished the conversion. The weekend sailors who sail 30 miles to an anchorage on Saturday, and motor home on Sunday. Or have a 5 mile slog to weather in 20 gusting to 30 in a channel not well suited to beating (we have lots of them here on the Chesapeake). Or more adventurous types who meander down the ICW. I'd love to end the philosophical debate about theoretical differences in diesel vs electric HP, or views on how a boat should be sailed, and hear stories from those how have completed it. Where are they? I do have a friend who had electric on a 43' distance cruiser, but it has been replaced with a diesel engine.

I did just do an interesting Yachworld search. Global, no country limits, no cost limits, no year limits, on boats from 35-45 feet, listed as "electric propulsion" (There is a search criteria for engine type). There are 10. Of those, 5 are labeled wrong or clearly day sailors. So globally, there are 5 electric powered cruising sailboats between 35 and 45 feet for sale. Interesting. And one of those is very comparable to what Jimmy is having built.
This one fell just out of your search, but kind of related to both your points: https://www.yachtworld.com/boats/201...maran-3495614/

Owner discussing (among other stuff) the electric/hybrid system of the boat:
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Old 18-02-2020, 06:04   #149
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Re: Jimmy Cornell goes Electric, with a Cat

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Originally Posted by mglonnro View Post
This one fell just out of your search
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*Range varies depending on cruising speed. The systems may be recharged while at sea under sail generating power from the propellers if fixed blade props are installed. Currently folding props are in use.
This note in the advertisement raises some questions. Did the regen not work as planned? Seems like they decided to operate in diesel electric mode instead.

In any case I guess that the right props will give the benefits of both worlds.

But I do like the extra top loading fridge or freezer:

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Old 18-02-2020, 10:40   #150
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Re: Jimmy Cornell goes Electric, with a Cat

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Another point to consider regarding specific advantages of a cat for going electric is, that having two motors, you can also use the two motors for hydrogeneration. Hence there is the double potential for harvesting energy when sailing.

With this, an Outremer 45 can, after sailing 6 hours with 10 knots, motor along with 6 kts for about 2 hours, using the energy harvested with hydrogeneration. This is calculated with fixed props. Using the adjustable pitch solution from Oceanvolt you can expect at least factor 2 more energy from the hydrogeneration.
We've read a lot of claims about hydrogeneration in this and other posts along similar topics. To date I've yet to see any real world data supporting these claims.
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