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**Adelie** · 21-09-2021, 05:47

Quote:

Originally Posted by ve0hak

I could believe that the cost of the engine and mechanical linkage is something comparable to the cost of an engine that burns dinosaurs, maybe a bit more expensive, maybe not.

The batteries are another story. Depending on the size of boat (power) and capacity (range) desired, I could easily see the battery bank costing a few tens of thousands. Especially if buying as a polished system with branded parts. As usual, the whole thing is possible much more cheaply with much greater effort by sourcing components individually.

One of the early posts in this thread indicated $38K including batteries.

Gerrit Coetzee · 21-09-2021, 05:50

Quote:

Originally Posted by NaClyDog

I don't mean to rain on your parade but just because someone says something in a video posted online, does not make it true.

I'm not disagreeing that the drag may have a negligible impact on performance, I'm simply stating this is not any kind of proof (I have not watched) unless all the inputs have been controlled and the results can be reproduced. Is this a person's experience or are they showing actual proof?

What you mean, this video is "not any kind of proof "???

Not good to make comments that seems retarded, as it is a bad reflection on a person. At least watch before commenting.

Any submitted information serves as evidence, and the weight that evidence carries as to its burden/capability of proof, lies in the lap of the beholder. Even if it is then adjudicated to say it has less weight, does not render it 'no proof'.

Think before ink.

Gerrit Coetzee · 21-09-2021, 06:07

Quote:

Originally Posted by NaClyDog

Is it trivial though? What may be trivial for you may not be for someone else. Trivial is subjective.

Actual and verifiable numbers would allow people to make their own determination of what is and isn't acceptable.

I can't say ' with all respect ', but you are argumentative, to the point of being called out.

If you would have watched the video, the OV is a supplementary system, to aid their solar system, whilst there is wind power generating too - both the OV and turbine powered by wind through the sails.

Should the additional generated power come at a loss of even 1-2 knots less speed, the aim is to get more battery stored energy. The loss of speed is then secondary to the main objective. respite the rhetoric of physics and numbers.

The dire urge to debate your point, blinds the perspective.

danstanford · 21-09-2021, 06:48

Quote:

Originally Posted by JC Reefer

The times in which regen can be taken advantage of is limited. For me this is limited to the point of useless.

Saying that, it’s going to be an option of with any brand that is marketing for marine electric motors. Might even be standard.

I’d consider going fully electric (if money were no object) but would not be interested in regen.

Can you elaborate? It seems to me that every source of potential power creation is needed to be successful be that regen, solar, or wind. The good news about these is that though they are in short supply at some times, they are essentially inexhaustible unlike your diesel tank.

Bullshooter · 21-09-2021, 07:16

It seems that some are posting without watching the video. If you don't want to watch the whole thing, how about 30 seconds?

Start at 12:58 if you want to see what the prop does.

Ericson38 · 21-09-2021, 07:44

Quote:

Originally Posted by seandepagnier

Almost. The diameter needs to be at least half the beam of the vessel for a monohull to achieve the 90% efficiency generally. The prop they are using is I estimate 1/6th the diameter it really should be and therefore below 30% efficiency and really should not be a consideration. It is a poor match, but maybe ok for them if they use it infrequently. It really should be a generating turbine though, not a propeller in that case as it is simply way too small to be efficient at propulsion.

The optimum propulsion prop can never be optimum for generation and vice versa. Variable pitch optimizes things somewhat but is not a substitute for being able to vary the camber and twist. So if it were fully flexible then sure.. and fish and dolphins already have higher efficiency, as tails are also a bit better than propellers but without room-temperature superconductors there is no way we can build mechanical ones.

I agree with this in general. There is an upper limit on diameter to where tip speed becomes excessive, or chord becomes so short that it will stall easily, or that surface area gets too great, but there is an optimum range for a given HP extraction need, and these props are too small in diameter.

Trawlerman · 21-09-2021, 08:01

I am not sure why there is so much skepticism on this product and the results shown in the video. The power that is being generated is only in the few hundreds of watts, typically around 350 watts give or take. Bearing in mind that this only represents about 1/2 of a horsepower, why would anyone expect much more slowing down? The power that the sails are providing are certainly more than a factor of 10 times this, and so the proportion of power devoted to generating electricity is rather small relative to the amount of power devoted to moving the boat. It would seem to me that this is entirely to be expected. Also, as we all know only to well, when you apply power to moving the hull, you typically fairly quickly come up to experiencing so called "hull speed" (a granted fuzzy edged speed) where the force resisting the hull motion is increasing exponentially. This effect then means that as the drag of the prop-generation comes into play when you un-feather the prop, the effect of "backing down" from the exponential curve is working in your favor. This is a long winded way of saying that this is likely much ado about nothing much.

**s/v Jedi** · 21-09-2021, 08:15

Quote:

Originally Posted by Trawlerman

I am not sure why there is so much skepticism on this product and the results shown in the video.

It’s the oilers, having none of this good for nothing electric stuff

danstanford · 21-09-2021, 08:44

Quote:

Originally Posted by Trawlerman

I am not sure why there is so much skepticism on this product and the results shown in the video. The power that is being generated is only in the few hundreds of watts, typically around 350 watts give or take. Bearing in mind that this only represents about 1/2 of a horsepower, why would anyone expect much more slowing down? The power that the sails are providing are certainly more than a factor of 10 times this, and so the proportion of power devoted to generating electricity is rather small relative to the amount of power devoted to moving the boat. It would seem to me that this is entirely to be expected. Also, as we all know only to well, when you apply power to moving the hull, you typically fairly quickly come up to experiencing so called "hull speed" (a granted fuzzy edged speed) where the force resisting the hull motion is increasing exponentially. This effect then means that as the drag of the prop-generation comes into play when you un-feather the prop, the effect of "backing down" from the exponential curve is working in your favor. This is a long winded way of saying that this is likely much ado about nothing much.

There are quite a few women in this world who think I should adapt your last sentence as my signature!

Ericson38 · 21-09-2021, 09:01

Quote:

Originally Posted by Trawlerman

I am not sure why there is so much skepticism on this product and the results shown in the video. The power that is being generated is only in the few hundreds of watts, typically around 350 watts give or take. Bearing in mind that this only represents about 1/2 of a horsepower, why would anyone expect much more slowing down? The power that the sails are providing are certainly more than a factor of 10 times this, and so the proportion of power devoted to generating electricity is rather small relative to the amount of power devoted to moving the boat. It would seem to me that this is entirely to be expected. Also, as we all know only to well, when you apply power to moving the hull, you typically fairly quickly come up to experiencing so called "hull speed" (a granted fuzzy edged speed) where the force resisting the hull motion is increasing exponentially. This effect then means that as the drag of the prop-generation comes into play when you un-feather the prop, the effect of "backing down" from the exponential curve is working in your favor. This is a long winded way of saying that this is likely much ado about nothing much.

You could get 2-3x the return on this expensive system if the prop was optimal for pulling rotation energy out of the water flow behind the hull. Drag is a result of pulling roatation energy out of the flow, but drag for drag's sake only results in random eddy currents and is not a figure of merit.

Yes, at hull speed, there is a great deal of excess power available. But getting to hull speed in open ocen sailing is is very conditional. So more prop efficiency should be the focus, not on batter technology, which is already moving upwards in a fashion avaliable to the general consumer.

**Adelie** · 21-09-2021, 09:08

The optimum diameter is the largest that gives adequate clearance to the hull for the existing shaft location.

The optimum prop that provides both propulsion and regen would be a CP prop. The shape of the blades would depend on whether you want to skew towards propulsion efficiency or balance the two.

harlem24 · 21-09-2021, 11:53

Interesstingly, the thing most people talking about the price are missing is, that the system you purchase is including tanks aka batteries.
If you take into account replacing the diesel tanks when repowering, the price difference would not be that big.
If you look at the prices of LiOn-batteries you see that there is much potential to get cheaper. Looking at the Natrium-Lion batteries coming in 2023 to the car market that cost a fraction of todays systems. We'll see where we end up in let's say 5-10 years.

**Adelie** · 21-09-2021, 12:19

Did you mean sodium-ion?
That’s at least 10yr out from commercial production.

Ericson38 · 21-09-2021, 15:03

Quote:

Originally Posted by Adelie

The optimum diameter is the largest that gives adequate clearance to the hull for the existing shaft location.

The optimum prop that provides both propulsion and regen would be a CP prop. The shape of the blades would depend on whether you want to skew towards propulsion efficiency or balance the two.

Optimum diameter for overall cost (not moving the shaft or its axis angle for clearance) or overall EP efficiency is not the same for all boats. Some boats can mount more diameter (less pitch) than others.

Some boats are better condidates for EP conversion than others.