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Old 29-10-2021, 05:25   #691
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Re: Jimmy Cornell goes Electric, with a Cat

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Originally Posted by jmh2002 View Post
Just to give a more real world example:

I'm sure you can imagine a situation in light air where the sails will barely set and boatspeed is minimal (especially since motion keeps shaking what wind there is out of the sails too), but with a bit of a push from propulsion a big light reacher will fill and set consistently and light cat might then do 8kn without too much trouble now.

That 'bit of a push' can create a lot more apparent wind generated boatspeed on a Cat.

So it would take A LOT of propulsion to motor at that same 8kn, but perhaps very little to motorsail.

Part of that is not so much the amount of propulsion, but just that consistent little push, preventing the boat from slowing down, and therfore keeping the apparent up.

Won't adding propulsion move the apparent wind forward making you bear off to fill that sail and reducing VMG?
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Old 29-10-2021, 10:55   #692
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Re: Jimmy Cornell goes Electric, with a Cat

Not sure if it was mentioned before, but I ran across this article yesterday of someone that seems happy with a competitor's hybrid system.

https://www.moonwave.com/three-years-hybrid-tq/

Motors and batteries, including changing both for upgrades as they are somewhat of a test bed, and they got a larger battery bank in the same size housing and upgraded motors so the 3yr old ones could be torn down for inspection(nothing wrong with them, just testing by the company) so they got experience with some of the longer term maintenance etc...
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Old 29-10-2021, 11:16   #693
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Re: Jimmy Cornell goes Electric, with a Cat

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Won't adding propulsion move the apparent wind forward making you bear off to fill that sail and reducing VMG?
Maybe, it depends on your destination
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Old 29-10-2021, 11:18   #694
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Re: Jimmy Cornell goes Electric, with a Cat

Increasing speed and bearing off probably will change VMG, whether it goes up or down will depend on how much each changes.
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Old 29-10-2021, 11:19   #695
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Re: Jimmy Cornell goes Electric, with a Cat

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Not sure if it was mentioned before, but I ran across this article yesterday of someone that seems happy with a competitor's hybrid system.

https://www.moonwave.com/three-years-hybrid-tq/
Yes I mentioned it and there have been multiple posts discussing it.

Wondering if you read any of the last few pages?
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Old 29-10-2021, 11:48   #696
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Re: Jimmy Cornell goes Electric, with a Cat

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Wondering if you read any of the last few pages?
Smiley faces can help, but don't usually negate rudeness. It's good to consider that before you post. (much like I shouldn't allow myself to be drawn into this, but I've had a bad day, so here goes)
Last mention of moon wave was 9 days ago, and I have a life.

I have read the entire thread(as it happened), but my apologies to your sensitivities that I didn't go back several pages and over a week of rabbit trails and off-topic conversations to find your post.

Beers on me if you ever find me in real life
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Old 29-10-2021, 12:34   #697
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Re: Jimmy Cornell goes Electric, with a Cat

The Moonwave posts should have had their own thread, as their situation is very different than Jimmy Cornell's. Gunboat 60, titanium saildrives, BMW battery pack---$$$$.

The author of those articles is a very positive person. She says the coral is thriving. She likes the third iteration of hybrid drive on the boat. However she does say "But if you plan to use your sailboat like a motor vessel and like to turn the engines on as soon as your speed drops to 5 knots to do 6 knots plus under power, than this is not for you."
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Old 29-10-2021, 13:36   #698
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Re: Jimmy Cornell goes Electric, with a Cat

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a very positive person.
A very negative person would not embark on such an experiment, right?
It is interesting to see the difference in managed expectations, and I feel that is important.

Negativity and Positivity should both play a part in planning and calculating systems like these, which are in their infancy. It must be understood that 'ideal' conditions are seldom the reality, and that you have planned and calculated as many of the inevitable shortcomings of any system you are using as possible.

How we manage risk, power, money, etc.... all plays a part in what is 'right' for us. Although we all manage each of those differently, nature and reality don't care about our feelings and do what they want when they want to do it.
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Old 29-10-2021, 13:59   #699
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Re: Jimmy Cornell goes Electric, with a Cat

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The Moonwave posts should have had their own thread, as their situation is very different than Jimmy Cornell's. Gunboat 60, titanium saildrives, BMW battery pack---$$$$.

The author of those articles is a very positive person. She says the coral is thriving. She likes the third iteration of hybrid drive on the boat. However she does say "But if you plan to use your sailboat like a motor vessel and like to turn the engines on as soon as your speed drops to 5 knots to do 6 knots plus under power, than this is not for you."

Sure, and it is a Gunboat 60, which sails extremely well too.
I noted that in my posts, as well as noting that it was a big budget program.

But I think that is the reality across the board for the most part given current technology and would be the same on an Outremer or other performance Cat.

On the other hand Moonwave also have a genset so they could run that and 'motor' (or motorsail) with the limitation then becoming fuel capacity, the same like other conventially powered boats.

So we have gone full circle from 'no genset' to 'no engines' and back to a genset.

This seems like a logical next step, but is still a costly one when the electric package is also taken into account.

I posted Moonwave in this thread really as an opposite example to Cornell's failure, to show what in fact can be achieved, if it's done right.

All great stuff I think, just still pricey for the moment.

But like all new or evolving technology someone needs to be out there trying it, pushing the boundaries, making the mistakes, and improving it for the rest of us to benefit from at some later stage.

It's a bit like electric cars. It's easy to point out all their possible weak points.

But the evolution to where we are today with combustion engined cars didn't happen in just a few years, it took a century or more, including building all of the infrastructure to support it - remember back in the day cars used to carry a jerry can of back up fuel because there weren't fuel stations on every corner. Range was still limited.

In my opinion, and without arguing niche use cases, a world cruising boat with electric propulsion and regen or not, still needs a genset in order to offer 'similar' capability to the exisiting non electric alternatives.

To me having the electric option is not so much about totally removing all combustion engines, it's about the other peripheral benefits:

- reducing the combustion genset's runtime and fuel burn. Fuel is likely to be a lot more expensive in the future.
- reducing the associated heat load, and noise, etc (plus a genset can be remote mounted in a 'better' location compared to convential propulsion engines which are often in the interior)
- some regen capability
- some silent running capability
- anchoring and maybe docking without having to 'short cycle' the combustion propulsion engines, which is really not very good for them
- flexible integration integration with the overall electric system onboard, including for example electric galley, and these days low powered aircon, watermaker, etc, too
- etc, etc


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Old 29-10-2021, 15:36   #700
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Jimmy Cornell goes Electric, with a Cat

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Originally Posted by jmh2002 View Post

To me having the electric option is not so much about totally removing all combustion engines, it's about the other peripheral benefits:

- reducing the combustion genset's runtime and fuel burn. Fuel is likely to be a lot more expensive in the future.
- …



The series hybrid arrangement you are talking about will not significantly reduce runtime and will burn more fuel compared to an ICE boat unless speed is sacrificed.

A parallel hybrid arrangement will equal run time and beat the series hybrid on fuel burn and have all the other advantages over ICE.
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Old 29-10-2021, 16:04   #701
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Re: Jimmy Cornell goes Electric, with a Cat

I think you misunderstood what I wrote.

I didn't mean reduce the genset runtime/fuel burn when motoring.

I meant one of the benefits of having the electric option (and of course solar + lithium + optimised electrical + performance cat) is that the combustion genset's runtime and fuel burn will be reduced.

Because charging will mostly be coming from solar + regen, and the genset will only be for a top up.

Also I think that for owners of such boats efficiency when motoring a long distance and having to use the genset continously is of a lesser consideration, because this situation will not occur as often compared to a convential non optimised boat.

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Old 30-10-2021, 01:57   #702
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Re: Jimmy Cornell goes Electric, with a Cat

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I think you misunderstood what I wrote.

I didn't mean reduce the genset runtime/fuel burn when motoring.

I meant one of the benefits of having the electric option (and of course solar + lithium + optimised electrical + performance cat) is that the combustion genset's runtime and fuel burn will be reduced.

Because charging will mostly be coming from solar + regen, and the genset will only be for a top up.
Exactly. And when the genset is used for the top up, it can run at max efficiency.

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Also I think that for owners of such boats efficiency when motoring a long distance and having to use the genset continously is of a lesser consideration, because this situation will not occur as often compared to a convential non optimised boat.

Also true. Especially if the attitude changes from 'burn diesel to solve problems' to 'sail according to the forecast'.

At a high level, I'm increasingly convinced that a series hybrid approach is the best one for 'many-day' cruising. If the genset has sufficient output to drive the boat at an 'acceptable' speed and to keep the batteries topped up when solar/hydro/wind generation haven't been able to, then many things become possible:
  • no propane required for cooking (use induction hob; perhaps camping stove as backup
  • no petrol/gasoline required for tender (use electric outboard; oars for backup)
  • only one engine on board (less maintenance) and only one fossil fuel (diesel), which is for backup/topup rather than the primary source of energy.

The likelihood of having no wind, no electricity generation, and a broken genset all at the same time seems quite low. And if there are appropriate backup solutions onboard, it becomes a case of 'exceptionally inconvenient' rather than 'life threatening'
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Old 30-10-2021, 03:35   #703
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Re: Jimmy Cornell goes Electric, with a Cat

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Maybe, it depends on your destination
My question was in response to the person who suggested that adding some power would increase the apparent wind seen by the boat and allow much higher speeds with very little engine power.
Upwind I am trying to imagine how you wouldn't have to bear off to maintain sail trim and gain the speed suggested since the apparent wind will move forward.
Downwind the apparent wind would drop with added power from the engine.
Reaching might work in the same way that the foiling boats trim for upwind even when going downwind due to the apparent wind moving so far forward.
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Old 30-10-2021, 05:05   #704
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Re: Jimmy Cornell goes Electric, with a Cat

Naturally, the AWA will come forward as power is added, but typically even if one must bear away a bit, VMG will increase, especially on an easily driven cat.

I sometimes do the same with a diesel when I have somewhere to be and not quite enough wind. A small amount of extra thrust can gain you quite bit of speed (and VMG).
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Old 30-10-2021, 09:47   #705
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Re: Jimmy Cornell goes Electric, with a Cat

Best overall fuel efficiency is a parallel hybrid.

A series hybrid will only gain an efficiency advantage over ICE or parallel by going slower.

If you have a diesel anything aboard you are still probably a 2 fuel boat as you likely are carrying gas for an outboard.
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