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Old 06-05-2017, 16:10   #811
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Re: Oceanvolt Hybrid Motor

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Originally Posted by Claude-D View Post




Since the talk is very much focused on hydro-generation at the moment, let me start with this Youtube video on board Kato cruising along at 20 to 25 knots… The hydro-regeneration at these speeds was comfortably above 4-5 kW per motor (up to 9.2kW! per motor) Of course, some speed is lost to the hydro-generation. But it is very hard to guess or measure how much, and frankly - who cares! One thing is sure, it is very much “insignificant", and very much in line with what Oceanvolt claims. (Extract from Oceanvolt FAQ: “Hydro generation creates drag of only 0.1 of a knot at boat speed of 7.0 knots - barely noticeable.”)

r.
Firstly Claude, may I say that I feel its a little disingeuous of you to use the example of 0.1 knots of loss at 7 knots when in reality the generation created is also minuscule.

Secondly I feel it is also disingeuous of you to pretend that a boat like Kato CRUISES at 20 - 25 knots by using this as an example of the output to expect.

As one swallow does not a summer make, a squirt of speed not an OV battery fully charged.

When one considers an ORMA 60 fully crewed racing trimaran holds the Brisbane/Gladstone record of around 18 knots, a more reliable and representative figure to use would be around 12 knots as case studies will show that a boat like Kato is a 300 NM /day boat , or around 12 knots.

You have possibly got a good product, but guilding the lilly the way you have in your advertising certainly makes me check things a little more deeply. Currently I just see smoke and mirrors.

The argument that one should cram on more sail when charging is dangerous.
As you would know ,one reefs for the gusts on a multi, which has been reinforced by the recent CW capsizes.
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Old 06-05-2017, 16:43   #812
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Re: Oceanvolt Hybrid Motor

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Originally Posted by Seaslug Caravan View Post
Firstly Claude, may I say that I feel its a little disingeuous of you to use the example of 0.1 knots of loss at 7 knots when in reality the generation created is also minuscule.

This was a quote from the Oceanvolt website. And more in line with the average cruiser. "Minuscule" as it may be it is still better than what you get from your diesel

Secondly I feel it is also disingeuous of you to pretend that a boat like Kato CRUISES at 20 - 25 knots by using this as an example of the output to expect.

Of course, this is spectacular hydro-generation, and fun to be on board to see it. Just as it was to sail at 20-26knots. And yes, there are other videos of Oceanvolt regen at more reasonable speed.

As one swallow does not a summer make, a squirt of speed not an OV battery fully charged.

When one considers an ORMA 60 fully crewed racing trimaran holds the Brisbane/Gladstone record of around 18 knots, a more reliable and representative figure to use would be around 12 knots as case studies will show that a boat like Kato is a 300 NM /day boat , or around 12 knots.

I will post a Video of the regen onboard Kato at 12knots for your information. And also one at 10 knots onboard another catamaran.
[/COLOR]

You have possibly got a good product, but guilding the lilly the way you have in your advertising certainly makes me check things a little more deeply.

And I welcome you checking!

The argument that one should cram on more sail when charging is dangerous.
As you would know ,one reefs for the gusts on a multi, which has been reinforced by the recent CW capsizes.
This is not the case... the regen does not affect the way you sail... So far nobody has noticed a difference when the regen is on...
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Old 06-05-2017, 17:21   #813
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Re: Oceanvolt Hybrid Motor

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Originally Posted by Claude-D View Post
1) 2250 RPM
2) 1800-1900 RPM You can see this on my Youtube video.
3) No
4) The first propellers fitted to Kato were the three bladed Gori 16.5" X 11" We got a maximum speed of 9.3 Knots. But power used at maximum RPM (2250) was only 10kW per motor. This was an indication that the propellers could use a bit more pitch. So we swapped the propellor for 16.5" X 13" This increased our max speed by a solid one knot at 8.4kW total output (This is the genset output) and also gave us a greater top speed (10 knots) at 2250RPM and the maximum power output of 15kW per motor.
Thanks. Now that we finally have some numbers to talk about:

So with 13 inch pitch under full power, non zero slip would mean 24,07 knots boat speed, and kato only has 10 knots, that means there is 58,45% slip, and propulsive efficiency is therefore less than 41,5%, as that value would result with zero viscous resistance and zero rotating slipstream and reality is obviously even worse. The real efficiency is likely to be around 30%...35% at that operating point. With diesel, suitable gear ratio and prop, over 60% would be possible. That is the price you pay for it from efficiency point of view.
That's what I meant in point 4)
Quote:
pitch while motoring is way too much for good efficiency
While regenerating with 1850 RPM, zero slip case is 19,79 knots, and boatspeed in real world 23 knots. Thus slip is -16%. Surprisingly large value, and would suggest stalling for most bladeshapes working as a turbine. Low pressure on the concave side facing aft, ie a foil working upsidedown compared to how it's designed for. It would need rounded (or better yet elliptical) leading edge like used in subsonic airfoils to keep attached flow at that slip value. Real world prop blades for use in water obviously have a sharp leading edge to avoid cavitation in normal mode (propulsion, not regeneration).
Stalling does necessitate reduced efficiency.

If that prop is from Gori, are you sure it has no overdrive mode?
If it does, do you know the pitch in that condition, and when OV uses it?
I'd like to correct any calcs above that would result.
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Old 06-05-2017, 17:24   #814
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Re: Oceanvolt Hybrid Motor

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Originally Posted by fabgo View Post
Would you express the same concern if I choose to equip my boat with fixed props vs. folding props? I am guessing the drag from a fixed prop on a diesel sail drive is higher than the spinning prop on an OceanVolt.

Regards,
- Fabian
Free wheeling fixed prop (or even stopped fixed prop) takes far less power than 2.5hp+ the OV spinning prop takes to produce 1800watts.

I have 2 blade fixed props, and I keep them in gear when sailing.
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Old 06-05-2017, 17:31   #815
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Re: Oceanvolt Hybrid Motor

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Originally Posted by Claude-D View Post
This is not the case... the regen does not affect the way you sail... So far nobody has noticed a difference when the regen is on...
Try light winds, i.e., less than 10kts. I'll bet you would notice the loss of 2.5hp.
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Old 06-05-2017, 17:37   #816
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Re: Oceanvolt Hybrid Motor

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Originally Posted by Claude-D View Post
So far nobody has noticed a difference when the regen is on...
Good. But it does not mean efficiency is high.
It means power regeneration of OV is small compared to how much propulsive power sails generate, and thus do not reduce performance too much. And that is applicable with the boats you are aware of, not all boats someone could in theory install OV system into.
Take a small sailboat, like 30ft mono with small stability, (not a canter) and OV drag would significantly reduce speed while regenerating. The drag does not vary much with sailarea, or boat size, or capability to carry sails, but with boatspeed and propsize. It is good to know regeneration is not too much of an issue for boatspeed reduction for larger multihulls.
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Old 06-05-2017, 18:01   #817
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Re: Oceanvolt Hybrid Motor

Global warming, BB? Really?
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Old 06-05-2017, 20:13   #818
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Re: Oceanvolt Hybrid Motor

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I challenge any of you to prove there is a significant reduction in speed on any boat you choose that has an Oceanvolt SD15. Any boat at all. I am challenging you to prove your assertions with empirical evidence, instead of just flapping your gums.

YOU define what is significant, if you like. Obviously it will be more than a few tenths of a knot because it has already been acknowledged and stated by those who have been on OV boats and directly observed the regen, that there is speed reduction to this magnitude.
Next time I'm sailing in 10kts or less of wind, I'll start an engine, put it in reverse @ ~1400rpm and see how much it slows down. Thats about 2.5hp. I'll let you know!
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Old 06-05-2017, 20:14   #819
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Re: Oceanvolt Hybrid Motor

Quote:
Originally Posted by Claude-D View Post
1) 2250 RPM
2) 1800-1900 RPM You can see this on my Youtube video.
3) No
4) The first propellers fitted to Kato were the three bladed Gori 16.5" X 11" We got a maximum speed of 9.3 Knots. But power used at maximum RPM (2250) was only 10kW per motor. This was an indication that the propellers could use a bit more pitch. So we swapped the propellor for 16.5" X 13" This increased our max speed by a solid one knot at 8.4kW total output (This is the genset output) and also gave us a greater top speed (10 knots) at 2250RPM and the maximum power output of 15kW per motor.
1800-2550 Prop shaft RPM with a 16.5 X 11 prop? Really???
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Old 06-05-2017, 20:20   #820
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Re: Oceanvolt Hybrid Motor

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Originally Posted by Just Another Sa View Post
Thanks. Now that we finally have some numbers to talk about:

So with 13 inch pitch under full power, non zero slip would mean 24,07 knots boat speed, and kato only has 10 knots, that means there is 58,45% slip, and propulsive efficiency is therefore less than 41,5%, as that value would result with zero viscous resistance and zero rotating slipstream and reality is obviously even worse. The real efficiency is likely to be around 30%...35% at that operating point. With diesel, suitable gear ratio and prop, over 60% would be possible. That is the price you pay for it from efficiency point of view.
That's what I meant in point 4)

Yes, your calculations are correct and yes, the percentage of slip is more for electric motors than diesel inboard engines. This is because of the greater torque of the electric motor. A way to visualise this is to think electric cars. You put your feet down, you get instant torque, you burn your tyres. That is your slippage... I am attaching an extract from Dave Gerr "Propeller Handbook" where you can read, and I quote "Slip, in fact, is actually required to produce thrust."

However, "propulsive efficiency" is to move the power from your batteries to your propeller efficiently. That is; How much power do you require to push a boat at a given speed versus how much power are you drawing from the batteries. (or from your diesel fuel).


While regenerating with 1850 RPM, zero slip case is 19,79 knots, and boatspeed in real world 23 knots. Thus slip is -16%. Surprisingly large value, and would suggest stalling for most bladeshapes working as a turbine. Low pressure on the concave side facing aft, ie a foil working upsidedown compared to how it's designed for. It would need rounded (or better yet elliptical) leading edge like used in subsonic airfoils to keep attached flow at that slip value. Real world prop blades for use in water obviously have a sharp leading edge to avoid cavitation in normal mode (propulsion, not regeneration).
Stalling does necessitate reduced efficiency.

I am not sure that I am following. Are you saying that the Oceanvolt are not very efficient in hydro-generation mode? Surely if we the system was 100% efficient in Hydro-generation mode, the boat will stop!!!

If that prop is from Gori, are you sure it has no overdrive mode?

Yes, this is an annoying feature of the Gori propeller (in my view) I could never remember if the propeller was in overdrive or not. But, I do not think we were in overdrive but I am not sure...


If it does, do you know the pitch in that condition, and when OV uses it?
I'd like to correct any calcs above that would result.
Ok I will go now and see if I can post the video of the boat Hydro-generating at 12 knots.
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Old 07-05-2017, 00:22   #821
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Re: Oceanvolt Hybrid Motor

[QUOTE=cwjohm;2387260]So what have we learned over last 100 posts. The law of conservation of energy still remains inviolate (phew - what relief) but the degree of drag of OV motors on boat performance remains contentious until measured by an independent credible party. May I interrupt this pythonesque argument which will no doubt continue to make a couple of other points.



For any 45-50ft cat I would regard two 40Kw motors with a milspec 60Kw generator as fully functional, and indeed equivalent to 2 55Hp diesels. If anyone is willing to donate them to me I will pay for the installation.
Chris, I believe that is massively overpowering your Helia. 40kW motors would just produce MASSIVE torque, complete overkill IMO. I think you should try and get on a properly spec'd EP boat, and experience the torque. When Kato II is back at The Boat Works, maybe you can get a ride?

[QUOTE]BB wrote:
Electric hybrid is completely viable for cruising, and may be, in fact, superior to a diesel engine system, DEPENDING on what criteria you value and DEPENDING on what type of cruising is being considered. I'm working on a white paper that examines all that we've learned, and I'll post that when it's finished. It considers cost, total cost of ownership, EP system quality & design considerations ( Serial vs Parallel, reliability, maintainability, performance in adverse conditions, and yes, limitations. There doesn't seem to be such a document or discussion that could have helped us on our journey, so I guess I'll have to do it

Just one comment on your concern about adverse conditions. What I have learned from discussions with some very experienced bluewater voyagers is the consistent message that there are ways to handle adverse wind and sea conditions besides relying on diesels to just power into it. The first rule of seamanship they stress should be "No fixed destination!-No fixed timetable!". It is also the message in Beth & Evans experience as she wrote in the great book The Voyagers Handbook, a must read. So instead of bashing into 45 knot headwinds, maybe put out a parachute and sit tight till it moderates. In other cases maybe bear off and go somewhere else.
Quote:

This form of argument which may be distilled down to "There are other options so the case is not made" may be all well and good in the courts as a defence against "innocence unless absolutely proven guilty" but it becomes a bit tiresome when used day by day in statements like "There are many reasons why the atmosphere is warmed so global warming is bogus", "The bible describes another version of the history of mankind so evolution is bogus". We find similarity here, where the mere fact that there are other options to using your fixed means of propulsion, means that the fixed means of propulsion should remain unused in any situation. ANY situation? Of course not, Chris, You are over-reaching a bit. I do not know whether anyone sees the irony here but what this amounts to is that we would spend significant amounts of money to incorporate modern propulsion methods so that we can devolve back to the days of Sir Francis Chichester in purposefully NOT using those modern means to take the safest way out of any situation. No, it just means that there may well be a more seamanship like tactic that is an alternative to bashing into weather. Again, you are over egging the analogy. Forereaching into big breaking seas and using the diesels ticking over for some modest headway us a very viable tactic, for example.

Indeed, one imagines a hard days sailing during a passage where winds and sea states have gradually been developing over the day and day has turned to night. Third reef has just been taken down at 35kn and 4m seas with some difficulty so much so that the fit and strong third hand hired especially for the passage sprained his wrist in the effort. The wife is in the head throwing up in a bout of extreme seasickness. I can then imagine in my minds eye BB piping up like Lord Nelson and quoting from Beth and Evans - The Voyagers Handbook "well chaps now is not the time to consider pressing a button and utilising our new fangled modern propulsion - our job is to latch on and venture into the dark and waves and combat Neptune himself by setting a parachute from the bow. I hope you don't mean deploying the chute from the bow, do you? The chute should be deployed in adverse conditions from the safety of the cockpit with the lines led outside the stanchions and lightly moused to the bases, so they pop. You know this,
right? And you should always have practiced this several times while both running and forereaching. Have you? I have, and you need to be certain what you need to do to make it work properly, FIRST TIME!
I feel confident that once he has been told in no uncertain terms where he can shove his parachute that he may have cause to reconsider his position.Deploying a parachute in this scenario is an eminently smart thing to do. Have you read the Drag Device Database? This is exactly what many, many cruising couples use as their "It's time to hunker down now Honey" tactic. Seasickness, fatigue, injury are all good reasons to deploy the chute and go make a cuppa tea. Parachutes are not only for storm survival, is all I'm saying. It is especially effective for multihulls.

Rob, you state that you are a cruiser, and you may not be as ancient as myself who is in his sixties, but you are no spring chicken. It seems to me that the first rule of sailing is to take a long hard look at your reasonable capabilities in any given situation.Absolutely agree! Unless you are an experienced sailor with decades of experience or a super athlete like Bear Grills with a finely honed survival experience it behoves you to take a bells and braces approach to all facets of cruising and in my view that applies to the most reasonable availability of propulsion for all situations you may reasonably find. Indeed, in learning I sailed with experts who has hundreds of thousands of nautical miles under their belts, and the same strong message was oft repeated "Remember, we are cruisers, so when in doubt get those motors on, and ensure the boat is under control". Sure, it is appropriate in many circumstances, but not all. It's not a car, Chris. You don't have to put it in gear and drive off every time things get a bit challenging. I mean if the crew can't sail the boat in adverse conditions, then I agree, maybe they shouldn't be out there? Seems obvious.

Leaving, all of this aside, you may well find some degree of frustration with EP in the most mundane of situations. For instance, there is no way you could get into a berth at Mooloolaba marina out of slack tide due to its cross currents, as you need to power the boat in and then slow it up quickly this requiring maximal torque. At Boatworks I found my boat put in a long back finger with clearance to other boats on 1m front and back and I had to get out of there and avoid all the other boats parked in the bays in front. To do this required maximum torque on the motors. Now you will say that patience is the key - just wait for slack tide or just wait for the other boats to go, but you will find that over time the restrictions of less torque will wear you down, as it has done in others who have given up EP for diesels.I;m surprised you chose torque as an argument for diesel over electric. You really need to get on Tony's boat and experience the instant boat control and torqey power of the SD15's. You really do.

So I remain resolute in my view. EP is viable IF an equivalent amount of torque is provided to that of diesel. To do otherwise is simply unsafe. Yep, I also agree with this. The SD15's are equivalent to the thrust of 45HP turboprop diesels, Beta 45 actually. If you need 55HP, they are too underpowered for your Helia. Unfortunately, this requires significant expense, an expense that only the very wealthy can afford. The added expense is the added LFP batteries to get the hour of full power and the DC Genset, but wait, you have a genset anyway,
so the difference is the batteries. It's not that bad, you can have a completely electric boat, which is great.


As to your white paper, this subject may not be in written form but it has been rehashed time and again in these forums and between yacht owners. The argument for TCO cannot be madeTOTALLY disagree!, as the savings between fuel usage for a generator to drive EP and diesels is no where near enough to justify the initial cost. The cost differential is the added LFP batteries, and the savings in diesel maintenance plus fuel savings over 5 years does add up. The ROI depends on how much motoring and how much EP motoring is done on solar storage and regen. It could be as high as 80% as Nigel Calder has pointed out.

There are many good reasons why someone would install EP. Financial justification is not one of them.The EP benefits FAR outweigh the additional cost, for us anyway, maybe not for others. Why don't you just admit this and stop tilting at windmills.Because our cost benefit analysis comes to the exact opposite conclusion of yours,
that's why.
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Old 07-05-2017, 02:35   #822
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Re: Oceanvolt Hybrid Motor

If a 15kw electric motor is equivalent to a 30kw diesel, why not use an electric motor to power the generator?
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Old 07-05-2017, 02:43   #823
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Re: Oceanvolt Hybrid Motor

RE cost benefit: we travel about 5000nm per year, our fuel expenditure is less than $1000 per year, including running a thirsty 18HP two stroke motor on the dinghy, which uses a fair proportion of that.

How long would it take us to break even?
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Old 07-05-2017, 05:11   #824
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Re: Oceanvolt Hybrid Motor

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RE cost benefit: we travel about 5000nm per year, our fuel expenditure is less than $1000 per year, including running a thirsty 18HP two stroke motor on the dinghy, which uses a fair proportion of that.

How long would it take us to break even?
For you - it doesn't make sense.
Let's see. Having electric propulsion also means some benefits when not cruising, in form of huge solar/battery bank which MUST be installed so things start making sense.

Now picture - not you, but other group of cruisers, who like and appreciate some basic comfort.
Now let's count. Let say - 6 friends cruising. Electric propulsion. It's just small part of energy consuming, as it's not happening everyday. Plus one or two hot showers per day for 6 persons. Cooking for 6 persons (electric stove, cook top etc.). Water maker. Laundry for 6 persons. Air condition anytime when it's desired. Dehumidifiers. Dive compressor. Entertainment system, laptops, tv, etc. Electric tools. ALL of that will run from same batteries, which on cruising days used mostly for propulsion.
If there's enough energy collected in batteries during sailing - without hesitation use EP when wind is weak, even go directly against wind to save time and mileage, etc, etc.

Now - how much fuel and noise will it take to generate this amount of energy on regular boat with diesels, genset and small 1kW solar array? I bet - a lot more than $1000, plus all that noise.
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Old 07-05-2017, 13:47   #825
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Re: Oceanvolt Hybrid Motor

Quote:
BB said

The SD15's are equivalent to the thrust of 45HP turboprop diesels.
When these sorts of claims are made then rational debate becomes impossible.

Quote:
Ranchero said

Now - how much fuel and noise will it take to generate this amount of energy on regular boat with diesels, genset and small 1kW solar array? I bet - a lot more than $1000, plus all that noise. Now - how much fuel and noise will it take to generate this amount of energy on regular boat with diesels, genset and small 1kW solar array? I bet - a lot more than $1000, plus all that noise.
I have all that. In 3 years I have travelled up the East Coast of Aus. 3 times to Whitsundays and once around the Pacific Islands. Cost of fuel was A$1500 per year. Remember this is not the difference as in an EP system the generator will have to run often.

TCO claims are nonsense.

Yes you do not have to suffer the noise and vibration, you can pretend you are protecting the environment, and you can boast loudly at sundowners as to how you have a state of the art boat. All good reasons for EP. Financial justification is not one of them.
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