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Old 23-11-2020, 06:34   #226
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Re: Jimmy Cornell goes Electric, with a Cat

If you follow UMA really for longer, you will have seen that they have been more then frank about their way of sailing.
Almost every time they say that they are not on a schedule and are not in a hurry.
They even wear shirts with those slogans...
Nobody expects from their channel to get advice how to put up a setup for weekend sailors that have to be at a certain point at a certain time.
Same with Jimmy Cornell, both have purpose built boats that suits their needs.
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Old 23-11-2020, 08:38   #227
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Re: Jimmy Cornell goes Electric, with a Cat

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I was replying mglonnoro.

I agree with you. No genset needed when condition are good for solar and wind is available most of the time.

Also not trying to say anything negative about UMA. All I wish is after their northern europe trip they can give another review on how the electric drive worked out in those conditions and what differences they noticed between that and the bahamas.

Maybe some misunderstandings. All good mate..


Being here in the 60'N myself I wouldn't expect any significant contribution of solar as far as propulsion goes (regen and shore power for that!), BUT hopefully enough for powering the instruments, lights.

I think the basic mode of sailing would have to be 'without engine' (as many people do in old wooden 6mR, 8mR boats). What I'd worry about is to have enough power for the chart plotter
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Old 23-11-2020, 15:16   #228
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Re: Jimmy Cornell goes Electric, with a Cat

Being at 60* N, you will likely have lots of wind. You're regen will be giving you heaps of recharging kW's to make up for the decreased solar output. Assuming you have efficient regen, that is.
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Old 23-11-2020, 15:23   #229
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Re: Jimmy Cornell goes Electric, with a Cat

Uma did talk about having a large wind gen hoisted up when at anchor. They felt the smaller cruiser type wind gen was not enough. Prop gen is good but you would have to sail for a decent amount of time every other day-which is fine.
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Old 23-11-2020, 15:41   #230
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Re: Jimmy Cornell goes Electric, with a Cat

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Originally Posted by mglonnro View Post


Being here in the 60'N myself I wouldn't expect any significant contribution of solar as far as propulsion goes (regen and shore power for that!), BUT hopefully enough for powering the instruments, lights.

I think the basic mode of sailing would have to be 'without engine' (as many people do in old wooden 6mR, 8mR boats). What I'd worry about is to have enough power for the chart plotter
I thought they had about 600w of solar, which mid summer should do nicely to run the boat. Isn't going to charge their 12 x 100A Battleborns overnight but then they are not motoring long distances, they are sailing, even if it takes them all afternoon and 30 miles of sailing to cover 10 miles of fiord. We could all be doing that in the future.

The big difference is they have time, we don't, well not just yet. Oh and they need to be different from other YT channels to generate interest in their business "Sailing Uma" which has to be full time making excellent videos.

Last winter they mentioned Greenland in one of the UK episodes, should be interesting if they go that way.

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Old 06-12-2020, 21:57   #231
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Re: Jimmy Cornell goes Electric, with a Cat

Just run across this while researching NEELs.

120k euros,50KW motor, 6 x BMW i8 10kwh batteries. The owner reckons 7 hours motoring on batteries. He lost me when he said thats more than what the diesel motor can do. It's his first boat.

Seems like a realistic scenario for the cruising electric sailing boat though.



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Old 07-12-2020, 04:07   #232
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Re: Jimmy Cornell goes Electric, with a Cat

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Originally Posted by Yihang View Post
Just run across this while researching NEELs.

120k euros,50KW motor, 6 x BMW i8 10kwh batteries. The owner reckons 7 hours motoring on batteries. He lost me when he said thats more than what the diesel motor can do. It's his first boat.

Seems like a realistic scenario for the cruising electric sailing boat though.



https://www.yachtingworld.com/featur...ainable-126310
Lets see...
* He has never owned a boat, but he knows what is needed for a boat power system.
* He hasn't accepted delivery, but he thinks it can go 6 or 7 hours. Hours? I measure motoring in distance, or at least speed for a time (which is distance). Realistically, he can probably stretch that 6 or 7 hours if he drops to a single motor at super low speed....
* He thinks that 7 hours is "no compromise." As a kid, we took our 40' ketch from Maryland to Halifax to start our summer vacation. No wind. With 125 gallons of fuel, we had to divert to Cape Cod to refuel. It was mostly a motor boat ride. A few years ago, we helped deliver a Catana 43 from Bahamas to Newport, RI, and while we had some 200 mile days under sail, we motored the last 48 hours. Yes, cruising is about sailing. Yes, schedules are bad. But that's reality. "7 hours" is a serious compromise for most cruising sailboats.
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Old 07-12-2020, 04:16   #233
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Re: Jimmy Cornell goes Electric, with a Cat

https://cornellsailing.com/2020/12/e...pE6OaJ6aUO3ZqQ
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Old 07-12-2020, 04:34   #234
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Re: Jimmy Cornell goes Electric, with a Cat

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Wow. That's a blow for oceanvolt and the regen crowd. I guess La Vagabond has even more incentive to do their project now. Maybe jimmy had too many crew. With just riley and elayna plus two wind turbines they might be able to get by.
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Old 07-12-2020, 05:40   #235
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Re: Jimmy Cornell goes Electric, with a Cat

I don't understand that. They were sailing, stopped using the fridges and electric cooker yet still didn't have enough power. Strange, considering just about every cruiser in the world manages to have enough power whilst sailing.

The article only mentioned regen from the motors. Didn't they have a large solar array for house loads? If I can get 1kW on my tiny Prout, they should easily get a 3 kW on a catamaran that size. Certainly enough to power the autopilot, fridges, and watermaker
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Old 07-12-2020, 05:47   #236
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Re: Jimmy Cornell goes Electric, with a Cat

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I don't understand that. They were sailing, stopped using the fridges and electric cooker yet still didn't have enough power. Strange, considering just about every cruiser in the world manages to have enough power whilst sailing.

The article only mentioned regen from the motors. Didn't they have a large solar array for house loads? If I can get 1kW on my tiny Prout, they should easily get a 3 kW on a catamaran that size. Certainly enough to power the autopilot, fridges, and watermaker
They didn't have that much solar, looks like a little over 1KW. I think what killed them is not having gas for cooking onboard, only having a microwave and induction chew a lot of power, especially for what looked like a crew of 5. Also no motor or gas for hot water. They probably also needed a lot of power for making water.

Jimmy says they plugged in to charge at a marina. doesn't that defeat the challenge?
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Old 07-12-2020, 10:26   #237
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Re: Jimmy Cornell goes Electric, with a Cat

That all seems quite strange. I hope there will be more details to come in the future.

It's even more strange compared to some other examples, even such as CatNewBee here https://www.cruisersforum.com/forums...ey-201795.html who seems to be able to go several days as a minimum with an all electric consumption boat (galley, washing machine, water maker, etc, plus all the other normal items)

... and CatNewBee only has Solar - no regen to add charging when sailing.

Maybe there are just some fundamental system design errors on Cornell's boat? But you would think that OceanVolt would get it right.

Really strange...
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Old 07-12-2020, 10:47   #238
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Re: Jimmy Cornell goes Electric, with a Cat

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Originally Posted by jmh2002 View Post
That all seems quite strange. I hope there will be more details to come in the future.



It's even more strange compared to some other examples, even such as CatNewBee here https://www.cruisersforum.com/forums...ey-201795.html who seems to be able to go several days as a minimum with an all electric consumption boat (galley, washing machine, water maker, etc, plus all the other normal items)



... and CatNewBee only has Solar - no regen to add charging when sailing.



Maybe there are just some fundamental system design errors on Cornell's boat? But you would think that OceanVolt would get it right.



Really strange...

I think itís 5 people and and the requirements to get them fed and watered with an electric galley and water maker. Theyíre looking at a minimum of 250-300 Ahr per day (all figures for 12V) just for those two things, almost 4kW. Add in all the other loads (2x fridge, electric winches, plus all the other usual things) for another 150-200 Ahr per day, another 2kW, for a total of 6kW. Excluding any motoring!

Our 1kW array generates 1.5-3.0 kW per day, depending on the sun and the length of the day. And if their regen only produced 1-2 kW per day then itís quite clear they had a big deficit.

For CNB and Uma, my understanding is only two people and in Umaís case a much simpler boat.

But yes, without a diesel generator, how suitable is all electric for a cruising boat that doesnít have access to shore power?
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Old 07-12-2020, 11:19   #239
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Re: Jimmy Cornell goes Electric, with a Cat

I think you are right. I think there was a fundamental system design error at the start.

it seems they just didn't properly calculate the realistic usage/demand vs the charging that would be available. That's a huge fail for any boat, regardless of the system being proposed.

Quite shocking that such an error could be made.

I'm all for an all electric boat where possible, but it still needs to be realistic for the expected use.

And I still think there should be some type of combustion generator (even if it's just a honda suitcase type genset) for backup and emergencies.

That's just good sense, and good seamanship.

But realistically, much like electric cars in many parts of the world, a hybrid makes more practical sense than fully electric at this point in time.

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Old 07-12-2020, 11:37   #240
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Re: Jimmy Cornell goes Electric, with a Cat

Well it is all about science, and not about whishfull thinking and excessive green marketing.

Electric works for many applications, even propulsion, if you have a proper source for the energy demand of the engine and a big enough storage when there is no source. 20 or 30A recuperation peak currents are ridiculously low charge currents for batteries meant for propulsion purposes, that may have to deliver hundreds of amps when pushing the boat. With no adequate source it will not work sustainably, you may be able to motor out of the marina, but not over a longer distance.

There is no perpetuum mobile and there is no free meal.

Just do your math properly and you will see what is possible / feasible and what not so much.
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