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Old 09-04-2021, 21:04   #526
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Re: Jimmy Cornell goes Electric, with a Cat

J.Cornell Catamaran:


The Oceanvolt Servodrive Pod, in recovery mode, seems to have a software problem..trying to find the right prop pitch?!
Could it not be easier to regulate fluctuating Voltage electronically....or maybe use something like a PV mppt regulator....and only change pitch once the voltage approaches certain limits?!


I am not an electronics savvy guy...maybe someone here knows more?


that would also be an interesring approach for a diy regen system off the transom.


There are many bicycle hubdrive motor/gen. on the market....they shld work well enough...anything from 500W to 4,5kW...some have regen. incorporated.
One can also make a suitable prop with a printer.....
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Old 09-04-2021, 21:55   #527
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Re: Jimmy Cornell goes Electric, with a Cat

patently ridiculous, the whole thing!
ZERO emissions!!!
1. a boat for >1 million Ä - made from resin, fibers, stainless steel, aluminium, lithium batteries, ...sails, ropes, antifouling...& all emission free produced! Not bad!
2. how many miles does it have to sail to make up for the much higher "carbon footprint" (term coined by a BP advertising campaign!) it has over the same boat with "dirty propulsion & cooking"?
3. 4kn with 1kW (=1,4hp) - this huge cat? sure...

THE showcase of environmental hypocrisy! Larry Pardey will rotate in his grave if he knew he is mentioned in context with this "endeavour" (should be "en-devour" from the resources it devoured!)
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Old 09-04-2021, 23:58   #528
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Re: Jimmy Cornell goes Electric, with a Cat

Quote:
Originally Posted by Statistical View Post
Oceanvolt usually shows a DC genset in their large system designs. Pretty sure the "no genset not even one for emergencies" was 100% Jimmy and coming from nobody else in the industry. Even if OV was sure their system would perform adequately in 99% of cases the genset provides a safety net that avoids very embarrassing headlines like this.
Still, failure is not embarrassing, it's necessary!
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Old 10-04-2021, 01:57   #529
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Re: Jimmy Cornell goes Electric, with a Cat

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Still, failure is not embarrassing, it's necessary!
I'm not sure in this case, it might deter many in pursuing a similar dream.
A circumnavigation with a more realistic approach to generation, usage and backup would have been extremely helpful and inspiring to the cruiser community and show the real potential of the available technology.
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Old 10-04-2021, 02:10   #530
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Re: Jimmy Cornell goes Electric, with a Cat

Failure necessary...yes...but one ne can plan and test..before going on such an expensive endeavour. Double U has a point mentioning the 600kg to 1t of resin...petro product? ...aluminium...needs lots of energy..mostly hydro though...dacron..is made of....Oil too...and an Oceanvolt system costing north of 150k EUR ....IT MAY BE BETTER TO REFOREST SOME 100 ha of tropical forest...and use a well tuned diesel....with PV panels, that also take long to recover their production energy....
I see some sensible ..and lots of taxmunching projects arising...with those huge funds being thrown out now....we will see if the new tech jobs outperform inflation caused by fresh $ on the market.


This all has to be approached intensely but with care not to jump to expensive premature conclusions.
This catamara zero emissions project was a prime example for a....what was it called...my latin is too rusty..
ejaculatio precox?


excuse my language
Neverthe less..this project was public enough to teach....
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Old 11-04-2021, 03:19   #531
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Re: Jimmy Cornell goes Electric, with a Cat

How would you come to the conclusion, that the OV system cost 150k?
Their proposal on the website states 75k, with a smaller battery but a 15kW DC generator.
https://oceanvolt.com/twin-saildrive-15/
Cornell did not share the exact config of the boat, but posted something about a 50kWh battery.
So 1kWh lithium battery is about 800€. So the missing 32,5kWh would cost an additional 26k. A 15kW marine DC generator will be around at least 15k. So a system without servo props would be at 86k. Take 10k for the one servoprop into account and then we are at 96k. Add 20k for the installation and we are still far from your 150k.
And we still have to take into account, that there are no tanks that need construction and installation, no fuel system to connect them to the engines, no engines to buy and install. So in the end it migth not be as much additional cost as one might think.
It's a new boat not a reconfig.
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Old 11-04-2021, 04:06   #532
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Re: Jimmy Cornell goes Electric, with a Cat

hi harlem24,
I asked for a quote to refit an existing cat.
Equipment was app. 2x servoprops (15kW), cp controller, motor/ charging/houseload- controller...or whatever it was called. Then the batteries...I dont remember the cap. ..but below 50kWh...in the 30ies somewhere.
FischerPanda genset, drive controll levers, mfd scren(s)


fuse and switchboards


expressly labour and consulting not included.
that was 120k something EUR..130k$..now there may have been VATincluded.. I dont remember.
That may be ok for a new boat but not for a 10+ years old...unless a good classic.


I understand that OV has to recovrr R&D costs...guess the servodrive system was expensive, time and money consuming...and theyll now surely get it right, wherby the exp. with this Cornell boat will help them. The only one who probably hurts is the owner of that cat. We should thank him for being amongst the 1st...esp. as he did this privately..i believe...hope he didnt get burnt too much.
I was quite keen to get started a year ago...work called me....and in the meantime we are a bit more learned about these isues...thanks to www ..forums...
Batteries $ have dropped quite a bit, still dropping
More manufacturers...spels comp.=better prices.
I remind of the 600w/5000$ wattsea thingi...ok for a marsrover..
If I go serial hybrid...which at the moment isnt feadable /energyefficient enough for a small boat ..under 100ft
Variations of parallel hybrid are feasable, with prop regen neefing to be examined case for case.
A diy off transom hydrugen may be best W/$....I am just researching that...
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Old 07-10-2021, 10:21   #533
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Re: Jimmy Cornell goes Electric, with a Cat

Didn't see this mentioned: Cornell successfully sold his cat and .."The future is indeed electric!"

(https://cornellsailing.com/2021/07/the-long-goodbye/)

From a full energy, raw material etc. point of view I think an old existing yacht (with a ~stinky diesel) is orders of magnitude more favorable but I still like the strive for electric propulsion.
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Old 07-10-2021, 11:42   #534
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Re: Jimmy Cornell goes Electric, with a Cat

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Originally Posted by blu3534 View Post
Didn't see this mentioned: Cornell successfully sold his cat and .."The future is indeed electric!"

(https://cornellsailing.com/2021/07/the-long-goodbye/)

From a full energy, raw material etc. point of view I think an old existing yacht (with a ~stinky diesel) is orders of magnitude more favorable but I still like the strive for electric propulsion.
Thanks for the article, Jimmy Cornell has given it a try, let's hope others improve on it.

But no, from a total lifecycle perspective electric has a much better environmental impact than diesel. Using an old, inefficient diesel engine is like driving an old truck from pre-catalyser days.
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Old 07-10-2021, 12:52   #535
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Re: Jimmy Cornell goes Electric, with a Cat

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Originally Posted by Simon.Sails View Post
Thanks for the article, Jimmy Cornell has given it a try, let's hope others improve on it.

But no, from a total lifecycle perspective electric has a much better environmental impact than diesel. Using an old, inefficient diesel engine is like driving an old truck from pre-catalyser days.
A couple of things stand out to me on this.

Firstly, either Ocean Volt had terrible practical knowledge of their own product or they were deceptive about disclosing the real world benifits. I had dealings with them years ago and believe they are more than just deceptive.

In 1500nm, in all sailing conditions, on a capable boat that is in the top 5 or 10% of the ideal boats for demonstrating the abilities of OV equipment in had net losses of energy stores fro 95% to 20%. That's an extremely poor result.

The article says they replaced the standard prop with the better servoprop system on the port side, but according to a previous article, the main problem was the servoprop in regeneration due to seastate.

La Vagabonde has a new boat coming, a much faster trimaran with one OV system. If it doesn't work for them OV will have lost any chance of clawing back some of the credibility they lost with Jimmy Cornell's boat.
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Old 07-10-2021, 13:53   #536
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Re: Jimmy Cornell goes Electric, with a Cat

Quote:
Originally Posted by Dave_S View Post
La Vagabonde has a new boat coming, a much faster trimaran with one OV system. If it doesn't work for them OV will have lost any chance of clawing back some of the credibility they lost with Jimmy Cornell's boat.
If I'm not mistaken think I saw a mention of investigating if two units could be fitted, slightly canted away from each other. Again I think this was in relation to La Vagabonde III Trimaran.

Of course if being more realistic regarding the of both energy demand and energy production this is no surprise I guess since oly one unit will probably struggle to keep up.

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Old 07-10-2021, 15:21   #537
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Re: Jimmy Cornell goes Electric, with a Cat

Quote:
Originally Posted by bowa View Post
J.Cornell Catamaran:


The Oceanvolt Servodrive Pod, in recovery mode, seems to have a software problem..trying to find the right prop pitch?!
Could it not be easier to regulate fluctuating Voltage electronically....or maybe use something like a PV mppt regulator....and only change pitch once the voltage approaches certain limits?!
Regulating the voltage output by the MG to the system voltage is the easy part. What is difficult here is that with the servo prop you are now controlling two parameters, power drawn and prop pitch. These both interact and will have an effect on shaft speed, which combined with the continuously varying boat speed when in a seaway, makes for quite a challenging control strategy to tune.

OV should be on top of this given what the system is designed for, but, itís not a simple thing.
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Old 07-10-2021, 15:44   #538
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Re: Jimmy Cornell goes Electric, with a Cat

JM.. Interesting with two motors.

Watching the video of the Schionnig doing 23kn, the owner says the tech is working on the electric motors as they were sailing. At one point the power generated spiked to 9.something kw. I'm guessing, but maybe that was an over change in prop pitch.

If that were possible, I wonder if it would work better with human override. There are times you wouldn't care if you lost 5kn if it meant you could quickly fill your batteries and at other times maybe the opposite would be true.

Can you do that?
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Old 07-10-2021, 16:26   #539
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Re: Jimmy Cornell goes Electric, with a Cat

The motors were not being " worked on" per se, they were just recording data and were in the way of Tony seeing the read outs clearly from the helm.
The spike in regen power output would have been from either the boat accelerating down a wave and/or the motor being switched into/ out of regen mode. Probably the former.
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Old 08-10-2021, 02:21   #540
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Re: Jimmy Cornell goes Electric, with a Cat

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JM.. Interesting with two motors.

Watching the video of the Schionnig doing 23kn, the owner says the tech is working on the electric motors as they were sailing. At one point the power generated spiked to 9.something kw. I'm guessing, but maybe that was an over change in prop pitch.

If that were possible, I wonder if it would work better with human override. There are times you wouldn't care if you lost 5kn if it meant you could quickly fill your batteries and at other times maybe the opposite would be true.

Can you do that?
It's not that simple. So if you try and draw too much power from the prop, it will just stall, shaft speed will drop and so will power output. There will be a control loop that will vary that load until the maximum power point is reached. If you're in a seaway and the boat is speeding up and slowing down, this will have to vary continuously. Then add multiple blade positions....nightmare.

It looks like the system works well for fairly steady state conditions, but is far too slow to react when the boat speed varies quickly. I'm not a control systems expert, but it sounds to me like they will need to go to a more sophisticated control strategy that involves both self learning (e.g. testing and learning the optimum blade position, shaft speed and load for a particular boat and boat speed) and prediction based on external inputs for speed and acceleration.

Or maybe continuously varying blade pitch and load in a sea way just doesn't work, so it could revert to a longer term testing strategy. E.g. holding a particular blade position and load for a minute, then testing the next until it narrows down on something that's close to optimal.
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