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Old 28-12-2017, 15:39   #991
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Re: Oceanvolt Hybrid Motor

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When I went to university engineering courses we did not learn about energy measured in units of "a lot". How many ergs are there in a lot these days?


That’s hours of amps.
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Old 28-12-2017, 15:47   #992
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Re: Oceanvolt Hybrid Motor

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....
And where did you get the impression I don't believe "the OV consumes power generated by the sails" ??? Of course I believe that because it is obviously true, and I have said so. Have you read the posts? What I say is that despite the drag, it is insignificant to the boatspeed for Kato, and presumably other performance cruising cats, including my new Freeflow 50. I never said anything about other boat types. If you have a bathtub hull cat, maybe it will have a bigger effect, but that is of no concern to me.
Ok, let's break the numbers down....

I'll be generous and give OV a 50% efficiency number. That's 50% from power generated by the sails to KW added to the batteries.

So that's 1hp per 350watts. To produce 9KW you are asking you rigging to produce an extra 25+hp (in addition to the power you are using to move the boat).

You may want to oversize the rigging on your boat.
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Old 28-12-2017, 15:55   #993
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Re: Oceanvolt Hybrid Motor

You're really challenging observed data with made up numbers? Just, wow.
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Old 28-12-2017, 16:00   #994
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Re: Oceanvolt Hybrid Motor

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Originally Posted by tp12 View Post
You're really challenging observed data with made up numbers? Just, wow.
Sorry to confuse you with an engineering discussion.
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Old 28-12-2017, 16:01   #995
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Re: Oceanvolt Hybrid Motor

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Sorry to confuse you with an engineering discussion.
You're not having an engineering discussion. You're having a confirmation bias led critique which ignores actual data. No engineer would do that.

And there's no need for your attitude, thanks.
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Old 28-12-2017, 16:12   #996
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Re: Oceanvolt Hybrid Motor

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You're not having an engineering discussion. You're having a confirmation bias led critique which ignores actual data. No engineer would do that.
Your position is interesting. I don't have anything against what OV is doing, nor I have said anything bad about the project/product. I'm simply trying to cut thru the marketing BS and explain how it works at the lowest level. And, no, I'm not familiar with the project/product but I do know what it must do in order to perform as claimed. That's the way engineers think. It's obvious others just enjoy the kool-aid and believe.
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Old 28-12-2017, 16:12   #997
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Re: Oceanvolt Hybrid Motor

Now that we have settled the regen issue, except to the liking of some of our fine "engineers" , I'll open another can of worms that you engineers will just love!

I also had the chance to sit down at the Boat Works with the owner of Kato, who is a fairly capable (intentional understatement) multihull sailor, ex racing car driver and mechanic ( so he knows about torque & power & engine efficiency, OK?) and talked to him in some detail about his Oceanvolt experience and thoughts.

I wanted to focus on 1) his impressions using EP under adverse conditions, and 2) his impression of EP vs diesel performance.

Now, I know you guys are not gunna want to hear this, but here goes.

1) He has been cruising for a full 3 months up and down the Australia East coast, giving the Oceanvolt system on Kato "a thrashing". He has motored into some heavy winds i.e. 30 kts plus during that time. He has no reservations about the SD15's at all to perform under adverseconditions, and his comment on the naysayers, not mine, was "they just don't know what they are talking about. Simple." He says the SD15kW are easily the equivalent of the performance of 50HP (37kW) diesels in the tough stuff. This was very reassuring to my wife and I, as so much hoohaw has been made by some on this forum to the contrary. The reason he has bow thrusters in NOT because he has EP, but because docking a 66' lightweight cat in high winds is a major challenge regardless of what engines/motors you have. OK?

As to the comparison diesel vs electric re performance, here is the context of his opinion. His previous boat was a 60 foot Schionning, very similar to Kato, a bit heavier since Kato is carbon, but as to loaded displacement, very similar. That boat had twin 75HP (56kW) Yanmar saildrives. He tested the motoring performance for that boat exactly the same as he did for Kato, in the same rivers at both Coomera and Noosa Heads. OK? he's a race car driver and he likes to go pretty much as fast as he can, so performance matters to him. OK? At WOT for the Yanmars with light displacement he got 11.3 knots average over up river down river flat calm conditions. He cruised with the Yanmars on one engine 1850rpm and got 7.5 knots. So, a quick boat, yes?

Are you sitting down? Have you guys got your slide rules ready?

On Kato with the SD15 and Gori props, he got 10 knots at max power under exactly same conditions. Yes, that is correct. With 2 x 15kW electrics he got 1.3 knots less top speed than 2 x 56kW Yanmar diesels at WOT.

He says he could feel he was under prop'd and he changed the Gori's to a bigger pitch, and now he gets 11 knots at full power. Which is very close, you will notice, to the best he got from his Yanmars. So, not to put too fine a point on it, but the 15kW Oceanvolts are giving very close to the same performance as diesels over 3 times the power capacity. I told you you wouldn't like it.

For cruising on the 11kW FP ADT-DC genset, at 8.4kW from the genset, he can motor nonstop at 7 knots.

Now, this is a credible report by a knowledgeable and experienced cruiser. If you want to call this fellow a liar, I dare you to do it to his face. If you do, I wanna be there

I personally place much more credibility on this empirical data and his credibility, than Cruising Forum "engineers" howling about broken Laws of Physics, and a HP is a HP, and other such comments.

As promised, when we get launched with our Oceanvolt Servoprop system, I will also do testing, and publish the data, warts and all.

Peace be with you
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Old 28-12-2017, 16:17   #998
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Re: Oceanvolt Hybrid Motor

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Originally Posted by DotDun View Post
Your position is interesting. I don't have anything against what OV is doing, nor I have said anything bad about the project/product. I'm simply trying to cut thru the marketing BS and explain how it works at the lowest level. And, no, I'm not familiar with the project/product but I do know what it must do in order to perform as claimed. That's the way engineers think. It's obvious others just enjoy the kool-aid and believe.
Why do you need to diminish your argument by rolling out your silly kool-aid comment and being insulting? It tells me you don't have any stronger argument.

Data is king for evidence based decision making. I want to see data and Bigbeakie is providing it and you are not. Why don't you focus on that, instead.
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Old 28-12-2017, 16:42   #999
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Re: Oceanvolt Hybrid Motor

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Originally Posted by tp12 View Post
Why do you need to diminish your argument by rolling out your silly kool-aid comment and being insulting? It tells me you don't have any stronger argument.

Data is king for evidence based decision making. I want to see data and Bigbeakie is providing it and you are not. Why don't you focus on that, instead.
First, don't pass out insults then refuse to accept them.

Second, I haven't seen any engineering argument, would you care to join the discussion?

Why don't you explain how the system works at the engineering level?
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Old 28-12-2017, 16:49   #1000
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Re: Oceanvolt Hybrid Motor

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Originally Posted by DotDun View Post
First, don't pass out insults then refuse to accept them.

Second, I haven't seen any engineering argument, would you care to join the discussion?

Why don't you explain how the system works at the engineering level?
I didn't insult you.

Again, data ... I want to see data. Bigbeakie has provided that and you're using speculation, insults and baiting and trying to pass it off as engineering. That's obvious.

I'm not going to engage you on that level. If you're able to challenge the data with something other than speculations and insults then lets hear it. Otherwise, his data stands alone until someone else can provide more data to add to the set.
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Old 28-12-2017, 17:00   #1001
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Re: Oceanvolt Hybrid Motor

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Originally Posted by tp12 View Post
I didn't insult you.

Again, data ... I want to see data. Bigbeakie has provided that and you're using speculation, insults and baiting and trying to pass it off as engineering. That's obvious.

I'm not going to engage you on that level. If you're able to challenge the data with something other than speculations and insults then lets hear it. Otherwise, his data stands alone until someone else can provide more data to add to the set.
But you did engage me. You told me my data was made up, I'm not an engineer, and I'm ignoring the real data.

I'd like to hear your number about how much hp the sails need to generate to put 9KW in the batteries.
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Old 28-12-2017, 17:03   #1002
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Re: Oceanvolt Hybrid Motor

Kw per knot is not “data”. The two units of measure are completely unrelated.
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Old 28-12-2017, 17:08   #1003
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Re: Oceanvolt Hybrid Motor

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Originally Posted by DotDun View Post
But you did engage me. You told me my data was made up, I'm not an engineer, and I'm ignoring the real data.

I'd like to hear your number about how much hp the sails need to generate to put 9KW in the batteries.
Engaging on that level ... You don't have any data, you're challenging the data that has been provided. You made a strawman situation up, with your efficiency numbers that aren't backed by anything, to try and discredit the actual data that Bigbeakie has provided. My pointing that out to you is not insulting you, it's stating the obvious.

I'm not providing any numbers because I don't have them - I'm not making claims that I need to defend, you are. I'm interested in this topic because I want to make an evidence based decision on whether these type of systems would suit my application and I see only one person doing the research, wearing out the shoe leather and making phone calls and, more importantly, providing actual evidence of their claim.

We've exhausted the usefelness of this conversation. I'm only interested these systems, how they work and real life data on actual installations.
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Old 28-12-2017, 17:20   #1004
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Re: Oceanvolt Hybrid Motor

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Originally Posted by tp12 View Post
Engaging on that level ... You don't have any data, you're challenging the data that has been provided. You made a strawman situation up, with your efficiency numbers that aren't backed by anything, to try and discredit the actual data that Bigbeakie has provided. My pointing that out to you is not insulting you, it's stating the obvious.

I'm not providing any numbers because I don't have them - I'm not making claims that I need to defend, you are. I'm interested in this topic because I want to make an evidence based decision on whether these type of systems would suit my application and I see only one person doing the research, wearing out the shoe leather and making phone calls and, more importantly, providing actual evidence of their claim.

We've exhausted the usefelness of this conversation. I'm only interested these systems, how they work and real life data on actual installations.
Any engineer understands my efficiency number. Any engineer understands how hp is used to generate electricity. The fact that you don't tells me you are not an engineer. Hence, you aren't stating the obvious, you are blowing about something you know nothing about.

For some reason you seem to think I'm desecrating your beloved choice. My data isn't doing that, it's simply stating fact.

Continue to believe what you choose, but you don't refute data you don't like unless you understand it.
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Old 28-12-2017, 17:24   #1005
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Re: Oceanvolt Hybrid Motor

So glad to someone else facing the same silly arguements.

Look, let's summarise the situation. EP can produce almost the same, that is ALMOST, not the SAME, boatspeed as diesels that are about 3 times the size. The reason the diesels need to much bigger is that they are much more inefficient than electric.

The water resistance curve tells the whole story. It is exponential. The old adage that to double your speed in water you need to overcome the square of the resistance and to do that you need to cube the power required, tells the whole story.

I have come to the conclusion that you can reasonably expect to get "about" one knot less top speed with EP that is "about" one third the size of diesels that give you that one extra knot. To me, that is acceptable.

The real benefit of EP is that you can cruise at nice cruising speeds for MUCH less power from the batteries than trying to hoon around at slightly faster speeds.

End of story. I'll now get onto something more productive, like outfitting a boat.
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