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Old 22-11-2016, 09:37   #406
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Re: Oceanvolt Hybrid Motor

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Originally Posted by ArmyChief View Post
I'm not trying to get into an argument here....and won't. My point is that HP rating of an inboard is calculated at the crank, there will be losses in gearbox. HP on an EV and outboard are calculated at the shaft (prop). I'm not an engineer..I leave that to the professionals. However, if you go to the main EV marine sites..there are charts for conversion from inboard diesel to comparable EV motor.

No need for argument. If the numbers work, I'll happily agree with you. It would be great if we had a new and better drivetrain available.


Sure there will be losses at the crank but for a hybrid, there will be losses in the generator, so it's largely a wash.

Also even if we ignore the generator losses, the transmission losses on the diesel are no where near enough to magically allow a 15hp electric motor match the performance of a 45hp diesel. Depending on which source you want to believe, it's on the order of 3-15%, so if you want to claim a 42HP electric can match a 45hp diesel, you might have something (but again that assumes you can store enough energy in a battery bank to feed the 42HP motor, once you add a generator, that goes out the window)

As far as the EV snake oil salesmen...which is probably why this thread has so many posts. Those who understand the physics understand, you can't use 1/3 the HP and expect the same performance.

So again, if you are going to claim magic electric HP, you have to back it up with physics.
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Old 22-11-2016, 09:55   #407
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Re: Oceanvolt Hybrid Motor

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Originally Posted by ArmyChief View Post
As long as installer understands the difference between HP at prop vs HP at crank and does the proper calculations...the EV drive COULD have more thrust than the "higher" rated HP number.

It is fairly plain that there are folks that insist on believing that EP is an example of "white mans magic". I don't expect them to change their minds until they see for themselves that it's just more smoke and mirrors.

My comments are aimed at the individual that may be on the fence and willing to listen to someone with decades of experience in the drives and motors that says the tech is not ready for a cruising sailboat.

When/if fuel cells are ready for prime time and not just space stations and experimental cars, I might consider a shunt wound DC motor with a commutator.
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Old 22-11-2016, 10:20   #408
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Re: Oceanvolt Hybrid Motor

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Originally Posted by valhalla360 View Post
Maybe it's the old "what doesn't kill you makes you stronger" principal? I'm sure the guys from the days of square rigging were better sailors than your average cruiser.

Big Beakie:Particularly his observations in "Electric Propulsion Makes Better Sailors"

And a lot of square rigged boats went down with all hands.

So in a nutshell we should adopt EP knowing that decision will put our crew and vessel in more danger if conditions deteriorate. So knowing that we will pay more attention to avoid potential dangerous situations thus improving our odds.

I have heard the same type argument used in relation to life lines (they make you "lazy"), harness+tether (that's what my hand is for), life raft (ain't gonna get in one), life jacket (ain't ever gonna be shark food) and other nonsense. If that's the line of the argument then you've lost me. We're not thrill seekers, we're cruisers interested in getting to the next destination uninjured with our home intact. If EP improves the odds of those goals then I'll be all in. But if EP reduces my chances even one scintilla of enjoying cruising then it isn't ready.
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Old 22-11-2016, 11:29   #409
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Re: Oceanvolt Hybrid Motor

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Originally Posted by ArmyChief View Post
I'm not trying to get into an argument here....and won't. My point is that HP rating of an inboard is calculated at the crank, there will be losses in gearbox. HP on an EV and outboard are calculated at the shaft (prop). I'm not an engineer..I leave that to the professionals. However, if you go to the main EV marine sites..there are charts for conversion from inboard diesel to comparable EV motor.
Nope, max HP at prop and camshaft are almost the same.

And those EV marine site conversion charts are marketing, not engineering figures.

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Old 22-11-2016, 15:26   #410
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Re: Oceanvolt Hybrid Motor

Smoke and mirrors. At 2200rpm the prop on a 15kw electric and 40kw (54hp) Yanmar will both absorb 15kw and provide similar trust. But 15kw @ 2200rpm is max rpm for many electric boat motors. But turn the prop 28% faster ( as a rule of thumb) and prop will absorb twice as much power and create twice as much trust. For the Yanmar that's 30kw @ 2800rpm. The electric motor can't do that. Is it important, yes and mainly when you are facing a problem.

The other issue is endurance, a sailboat with decent tanks maybe able to motor for two to four days at 6kn. An electric boat maybe three - six hours at 6kn and then continue at 6kn as long as you have a 20kw genset to power the 15kw motor.


Quote:
Originally Posted by ArmyChief View Post
I'm not trying to get into an argument here....and won't. My point is that HP rating of an inboard is calculated at the crank, there will be losses in gearbox. HP on an EV and outboard are calculated at the shaft (prop). I'm not an engineer..I leave that to the professionals. However, if you go to the main EV marine sites..there are charts for conversion from inboard diesel to comparable EV motor.
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Old 22-11-2016, 17:11   #411
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Re: Oceanvolt Hybrid Motor

These guys are having some EP teething pains it seems:

https://news.usni.org/2016/11/22/uss...delined-panama

I know it's not really relevant to a cruising boat but EP has unique problems that will have to be found through analysis and actual on-water experience. We will no doubt all benefit by the early adopters' experiences.
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Old 22-11-2016, 23:13   #412
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Re: Oceanvolt Hybrid Motor

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Originally Posted by Seaslug Caravan View Post
Love the Video.

I assume you are joking though.

Nothing to do with horsepower or torque , its all to do with TRACTION.

Little tractors little wheels are SPINNING.

Very Funny
We don't often agree, but yeah, surely he's joking?
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Old 23-11-2016, 02:43   #413
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Re: Oceanvolt Hybrid Motor

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We don't often agree, but yeah, surely he's joking?
Unfortunately, it seems that he wasn't. He really believes this stuff.
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Old 23-11-2016, 06:02   #414
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Re: Oceanvolt Hybrid Motor

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Originally Posted by BigBeakie View Post
So an 18HP petrol/gasoline powered tractor with the same weight and wheels as the steam tractor shown, would be able to drag the 800HP John Deere backwards, eh?
If the wheels of the heavy iron tractor don't slip then with a much smaller HP engine it can out-pull a much larger HP tractor that is lighter and has less grippy tires. I've done it many times.

Look at it this way. If the big heavy steam tractor just locked its wheels then the 800HP tractor probably could not even drag it backwards in that loose soil. As soon as the heavy steam tractor starts to apply torque then it can easily pull the 800HP tractor backwards. How fast it can pull is related to HP but whether or not it can pull at all is related to torque and the friction of its tires. One can achieve massive torque through gear reduction with even a tiny engine. That steam tractor could probably pull the 800HP tractor with a 10hp engine and the right gear lineup.

But this has nothing to do with boats. A boat requires forward velocity to maintain steerage. It takes horsepower and torque to reach a certain boat speed. Less horsepower means less speed no matter what huge starting torque you have. HP is unrelated to torque unless you also discuss time and distance.
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Old 23-11-2016, 11:36   #415
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Re: Oceanvolt Hybrid Motor

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But this has nothing to do with boats.
Exactly. Somehow a tractor pull between a steam engine and a John Deere proves electric motors are better?
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Old 24-11-2016, 05:18   #416
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Re: Oceanvolt Hybrid Motor

Is it something like this?? Sailing Uma: Step 17 "Electro-Beke (part 1)" on youtube.
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Old 24-11-2016, 18:27   #417
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Re: Oceanvolt Hybrid Motor

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Of course not, you're the one that erroneously included the "h" in your posting. Nice to see that all of your own references confirm that you were wrong.

Just as you incorrectly put the nonsensical "/h" after HP.

Stu AKA pedant:congrats on not seeing the sarcasm and being trolled! Guy captains his own 70',sure he know what's going on.

Anyways I've read here about 7 hp electric being the same as 14 hp diesel,trains,nuclear aircraft carriers,etc and having skimmed through,a few points to reiterate.

a)Electric hp is not worth twice that of diesel.The company that made those claims went bankrupt,perhaps due to installing their system into a cat charter fleet and having them torn out a year later.Solomon Tech.

b)I read on another forum how Nordhavn sued the hell out of Siemens-and won- when The promised gains in efficiency didn't come to fruition. Owner of Nordhavn wondered how they could be so dumb as to think they could bend the laws of physics by thinking a diesel electric could be more efficient than a regular diesel.

c) Trains. LOL

c)Aircraft carrier LOL x1000.

d)A European company offered a diesel electric and regular diesel boat,40'.
DE cost 10% more,was 5 knots slower,and used 15% more fuel.

e) Several diesel electric companies touting miracles have come..and gone.
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Old 27-11-2016, 14:35   #418
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Re: Oceanvolt Hybrid Motor

Let me know if this system ever comes availible, the wife and I love the idea of being totally non dependant!
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Old 27-11-2016, 17:03   #419
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Re: Oceanvolt Hybrid Motor

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Let me know if this system ever comes availible, the wife and I love the idea of being totally non dependant!
By non-dependant, do you mean stopping every 600nm to fill up the diesel tanks for the diesel motor or stopping every 600nm to fill up the diesel for the diesel-electric generator. I could add enough batteries to go the whole 600 nm using batteries only. That's 3,000 x 12v x 200 a/h batteries. If lead acid this will add another 120 tonnes to your boat and will take about 300 days to recharge and you might have to then do a top up charge to make up for the drain over that time. Make sure you get fully sealed because you might spend your entire time topping up batteries. If you only do short trips, the calculations are not so extreme. A maximum 50 miles journey, only needs, 10 tonnes of batteries and will recharge in 25 days.

For an all electric storage that provides the identical service as diesel,we will need to have a battery that weighs 150kg and provides 3 megawatts of energy. This should recharge fully in 1/2 hour and last forever. That's just the energy storage system.
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Old 27-11-2016, 21:38   #420
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Re: Oceanvolt Hybrid Motor

I'm not sure what he meant by totally non dependant either, but setting up strawmen scenarios to try & discredit EP is really silly IMO.
The batteries are to handle the 90% of motor use. A DC genset handles the other 10% of motor use, IF you cruise in an area that demands extended motoring times. Of course, you can always CHOOSE to motor for hours on end if you wish.

An earlier post made reference to a Youtube showing a young couple's conversion of there mono "UMA" to a 4.8kW electric motor, no DC genset. They bought a second hand motor and all the bits to put it all together. Not the way I would, or am, doing it with OceanVolt, but if you go to their website SailingUMA.com you'll see that they have been happily cruising up and down the US eastern seaboard, both offshore and ICW, and to the Carib for 3,000 miles on solar & regen alone recharging their batteries. They have "yet to use their electric motor for more than 30 minutes at a time..."

While I'm here, I'll point out that I have been doing some checking on a couple of things while the EP bagging has been running it's course, ofcourse.

Just a few factoids for y'all:

1. OceanVolt have over 100 installations of just their 15kW SD15 system alone, all over the world. There have been NO warranty claims to date of faulty component(s), except one bad battery.

2. I have communicated with a number of OV users and every single one is delighted with the reliability and performance. Example, In NZ, a 50' cat regularly motors into 25 knot headwinds gusting 30, on 2 meter seas with chop, at 5 to 6 knots using 5kW to each motor. No, it is not a condomaran but has hulls designed for sailing, but still......In Brittany, a fellow has cruised for 9,000 miles so far, often under adverse conditions with NO adverse effects. Loves his EP, and he is not a newbie to cruising.

3. EP systems that I'm aware of that were taken out and replaced with diesels had major system faults and/or design issues. Such as, Controllers failing repeatedly, motors chronically overheating, electronic bits under spec'd and blowing under high load. Whadayouknow, all EP systems are not the same!

4. The technology of regen is becoming a game changer. New developments gives 300% more power than previously. And previously it was pretty damn good anyway.

So wake up guys, things are changing.
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