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Old 16-12-2018, 19:40   #1726
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Re: Oceanvolt Hybrid Motor

Quote:
Originally Posted by ssmoot View Post
So if I understand correctly, the only reason you're considering EP is to have a large generator onboard for house loads since you only have room for one diesel?
Well not only, but mostly in the current scenario. Perhaps some ability to use the bank will arise, perhaps some alternative sources will reduce fuel usage.

> You accept that you'll:
> Increase weight with the large generator plus motor
> Will lose some amount of volume in the engine bay

If that is necessarily the case. Of course depends on what was there before, I understand a lot has changed in 50 years.

> Have you considered a large alternator?

Yes, that is in fact the way I am likely headed until this idea arose.

The higher electric output from a powerful dedicated genset is attractive.

The need for output going to propulsion will usually be minimal, compared to that required for making water at a high gph rate and charging the freezer plates, neither of which I want to do from battery-stored power.

So just using a tiny fraction of a big propulsion engine's output for many hours per week, while living on the hook for weeks at a time, seems very wasteful and will require longer runtimes.
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Old 16-12-2018, 19:42   #1727
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Re: Oceanvolt Hybrid Motor

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Originally Posted by ssmoot View Post
Of course "loads will be higher"
You're right in the rest of your post except this one bit I have to help with so we all understand each other.

The loads are the same Regen on or off. The wind blows. Your boat speeds up until the drag force equals the wind force with Regen off. This is because drag increases with speed.

Now turn on the Regen. What tells the wind to blow harder? Nothing. It's the same force. You simply are bashing less water per second (going slower). The force on your sails is the same. Drag on hull decreased but drag due to Regen increase. They match and Newton is happy.

Again, the wind force never changes. Just your where the drag comes moves from hull to Regen.
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Old 16-12-2018, 19:43   #1728
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Re: Oceanvolt Hybrid Motor

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Originally Posted by bridaus View Post
I'd only consider it on new, repower, or if I was looking for a project.
I agree.

Many of the boats I'm looking at have no working inboard, often propulsion is an outboard.
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Old 16-12-2018, 19:48   #1729
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Re: Oceanvolt Hybrid Motor

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Originally Posted by bridaus View Post
Two people agree and it's marketing?

Nah, you guys just aren't satisfied when the rebels form an alliance.

When I have some time this week I'll stir up some controversy. I'm planning on questioning Gerr's transmission efficiency numbers. I don't believe them.

Nope, it's the marketing hype....


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Originally Posted by BigBeakie View Post
" is a game changer for cruisers.

Quote:
Originally Posted by BigBeakie View Post
And that is why the diesels CAN go about 1 to 2 knots faster than EP at WOT, because they have all that energy density that they can just throw away with the extra revs, along with heat & noise & friction. Assuming you've sized your diesels 2 to 3 times bigger than the electric, of course, as you have so elegantly shown.

Sometimes I have to smile when the diesel guys crow about DD "efficiency" compared to hybrid. It may be true (marginally) but it's only because diesel is so massively energy dense in comparison, that they can AFFORD to use such inefficient ICE which puts only about 25% of that energy density to work.

All marketing BS, i.e., fake news!
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Old 16-12-2018, 19:50   #1730
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Re: Oceanvolt Hybrid Motor

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Originally Posted by Dockhead View Post
Well, I think the point is a "few hundred watts" is a meaningless quantity of power for propulsion purposes.



If you intend to produce enough power by regen to use later for propulsion, then you need to be producing kilowatts, probably many of them. This would indeed require attention to the things TD mentioned.
I beg to differ. If you can make 400w for the next 10 hours, you can cruise for free for an hour tomorrow when the wind is dead. That's an automatic 10% increase in diesel economy.

Typical hydro generation is around 80% efficient. Do I expect props to be as efficient? No. Do I expect them to be 10% efficient as was claimed with no citation? I'm going to need more than someone's mere assertion to believe that. At least some personal anecdote at least.

svReality's boat went from 6.8kts (on one motor at 15kW) to 6.3kts. So... at 11kW on one motor with the other in neutral he should be doing the same 6.3kts? That seems pretty suspect to me. Though I suppose if it's correct that's pretty impressive performance.

Here's what I actually said originally though:

Quote:
If your batteries are already full during times of excess, then make water for free instead. Or run the air conditioning. Or take hot showers. Or run up the motors and point a few degrees higher.
Do you believe people are having Watt & Sea generators ripped off their hulls? That's the kind of power we're talking about. Do you find it credible that you should even for a moment consider the sail loads or drive mounts after looking at the lowering mechanism for those generators?

I'd expect much higher drag loads from catching a fishing net. Is it a genuine concern of yours that a missed net will rip off your sail drive and put a big hole in your boat?

This all sounds pretty far fetched to me.
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Old 16-12-2018, 19:53   #1731
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Re: Oceanvolt Hybrid Motor

Quote:
Originally Posted by bridaus View Post
#1
Freeflow 46
Yanmar 54HP 4JH5E
7 knots on one engine at 2250rpm using MAXIMUM 17kW output at prop
Brunton Autoprops 16.5" don't know the pitch.

#2
Slyder 47
SD15
7 knots using 15kW (not output at prop)
I'm assuming this is the OV prop, not the 17" Gori feathering that the Slyder usually uses?

I think in the end we don't have enough data to tell what is going on. Autoprops aren't efficient? Yanmar old/not producing? Yanmar specs incorrect? Slyder slightly faster hull/clean hull? There are so many possibilities here I don't know if we can get any more out of these examples.
Corrected it!

I keep bringing up LOAD! It's possible the prop on the 4JH5E is only pulling 13KW. How would we know?
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Old 16-12-2018, 19:54   #1732
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Re: Oceanvolt Hybrid Motor

Quote:
Originally Posted by ssmoot View Post
I beg to differ. If you can make 400w for the next 10 hours, you can cruise for free for an hour tomorrow when the wind is dead. That's an automatic 10% increase in diesel economy...

But that's only 4kW/h, less storage losses. Maybe my dinghy could motor for an hour on 3.6kW/h -- slowly -- but the mother ship? Or anyone's mother ship? That's less than 5hp for one hour.


3.6kW/h is only a few minutes of motoring, for the two example boats in the immediately previous post.
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Old 16-12-2018, 20:02   #1733
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Re: Oceanvolt Hybrid Motor

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Originally Posted by bridaus View Post
You're right in the rest of your post except this one bit I have to help with so we all understand each other.

The loads are the same Regen on or off. The wind blows. Your boat speeds up until the drag force equals the wind force with Regen off. This is because drag increases with speed.

Now turn on the Regen. What tells the wind to blow harder? Nothing. It's the same force. You simply are bashing less water per second (going slower). The force on your sails is the same. Drag on hull decreased but drag due to Regen increase. They match and Newton is happy.

Again, the wind force never changes. Just your where the drag comes moves from hull to Regen.
You're of course correct, but we aren't talking about exactly the same thing. I was referring to the choice between pulling in some sail for comfort and just turning on regeneration.

I feel like I have to triple qualify everything or it'll be taken out of context, so to be clear, I'm not referring to leaving more sail up than you otherwise would for the wind you have. If you don't mind a bit of bashing, go ahead. If you feel like losing a half knot will be more comfortable, consider making power "for free" instead of pulling in a bit of sail.
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Old 16-12-2018, 20:11   #1734
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Re: Oceanvolt Hybrid Motor

Quote:
Originally Posted by bridaus View Post
I saw one at about 1kW and the other at about 500W and also wondered... How can they be different?
Yes, as I understand it that film was done during sea trials and the starboard readout had a glitch.

Too bad we don't have a bunch more cases to look at, but for now, it is what it is. Hopefully maybe sv Reality can grab some iPhone footage of his testing? Hint, hint?

The regen figures do jump around as there is a slight lag in the display, it is not instantaneous readout. I heard they were working to smooth out the display readings so it represented more of a "rolling average" type readout, which would be more useful.
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Old 16-12-2018, 20:17   #1735
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Re: Oceanvolt Hybrid Motor

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Originally Posted by ssmoot View Post
I beg to differ. If you can make 400w for the next 10 hours, you can cruise for free for an hour tomorrow when the wind is dead. That's an automatic 10% increase in diesel economy.
The conversation has been around 15KWh cruising, did we change to 4KWh cruising?

400W for 10 hours = 3920Wh into the batteries (2% loss). 3920Wh from the batteries = 3842Wh into the EP which = 3650Wh at the prop. Slow cruising during that hour!


Quote:
Originally Posted by ssmoot View Post
Typical hydro generation is around 80% efficient. Do I expect props to be as efficient? No. Do I expect them to be 10% efficient as was claimed with no citation? I'm going to need more than someone's mere assertion to believe that. At least some personal anecdote at least.

svReality's boat went from 6.8kts (on one motor at 15kW) to 6.3kts. So... at 11kW on one motor with the other in neutral he should be doing the same 6.3kts? That seems pretty suspect to me. Though I suppose if it's correct that's pretty impressive performance.


Here's what I actually said originally though:



Do you believe people are having Watt & Sea generators ripped off their hulls? That's the kind of power we're talking about. Do you find it credible that you should even for a moment consider the sail loads or drive mounts after looking at the lowering mechanism for those generators?

I'd expect much higher drag loads from catching a fishing net. Is it a genuine concern of yours that a missed net will rip off your sail drive and put a big hole in your boat?

This all sounds pretty far fetched to me.
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Old 16-12-2018, 20:27   #1736
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Re: Oceanvolt Hybrid Motor

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Originally Posted by OldMan View Post
Nope, it's the marketing hype....








All marketing BS, i.e., fake news!
Two can play that game! If you want me to throw back all the silly statements made by some of the others here, in bold type, to play your game, well that's easy....

Ok, how about you enlighten us with some data and prove your case. Show us a comparable boat with 15kW (20HP) diesels that can post these numbers. You may have some difficulty because 45 foot condo cats with 20HP donks would be a rarety, I would have thought, but, good luck with that.

And if you don't think a cruising couple could use a lazy 2 kW of power an hour as they sail along instead of running their Honda 2.2 genset, fine. I know plenty that would.
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Old 16-12-2018, 20:42   #1737
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Re: Oceanvolt Hybrid Motor

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Originally Posted by Dockhead View Post
But that's only 4kW/h, less storage losses. Maybe my dinghy could motor for an hour on 3.6kW/h -- slowly -- but the mother ship? Or anyone's mother ship? That's less than 5hp for one hour.


3.6kW/h is only a few minutes of motoring, for the two example boats in the immediately previous post.
You're right. Those numbers are too optimistic. But comparing it to pushing the boat is a stretch as well. Let's meet in the middle. Maybe you pull 600w off both legs combined. Because I can't think of a great reason to only run one. Can you?

Also worth noting that by running both motors we've got less reason to be worried about our saildrives flying off the boat from the tremendous forces. It's a good thing no one ever installs engines bigger than 1kW on a boat. Can you imagine the carnage?

Now I've got 5.4kW to play with for an hour. 4kts sound fair to you?
And if I've got 3kW of solar? I can probably double that easily.

These are not insignificant amounts of power. Still far from the most compelling reason to consider EP IMO, but regeneration alone, for that single work-day, will cover 1,200L of water with your Spectra watermaker. When you put it that way, it sounds pretty impressive to me.
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Old 16-12-2018, 20:56   #1738
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Re: Oceanvolt Hybrid Motor

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Originally Posted by OldMan View Post
The conversation has been around 15KWh cruising, did we change to 4KWh cruising?
I don't think anyone's put a number to what "cruising" means. But I'd expect 5kts SOG to be nice.

Quote:
Originally Posted by OldMan View Post
400W for 10 hours = 3920Wh into the batteries (2% loss). 3920Wh from the batteries = 3842Wh into the EP which = 3650Wh at the prop. Slow cruising during that hour!
Indeed. I think you could squeeze a bit more out. But I don't think I'd mind trying to gamify my boat speed within reason as long as I'm still making forward progress.

It seems like for some people anything under ~6kts and it's time to pull the sails and juice the throttle. I suppose if I think about jets, then "cruising" speed is a lot closer to top-speed than 50% top-speed. So that's maybe a fair assumption on your part.

4kts is faster than "Fastest Known Time" record holders can hike though. If I can manage close to that, for "free"? I'd be pretty satisfied. Bumfuzzle managed to average 5kts right? Close enough for me.
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Old 16-12-2018, 21:02   #1739
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Re: Oceanvolt Hybrid Motor

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Originally Posted by BigBeakie View Post
Two can play that game! If you want me to throw back all the silly statements made by some of th eothers here, in bold type, to play your game, well that's easy....

Ok, how about you enlighten us with some data and prove your case. Show us a comparable boat with 15kW (20HP) diesels that can post these numbers. You may have some difficulty because 45 foot condo cats with 20HP donks would be a rarety, I would have thought, but, good luck with that.

Comparing rated total output between EP and Diesel is the mistake with the argument.


1) Rated output is not what determines efficiency, load determines efficiency.
2) Diesel KW is less capex than EP KW (with necessary other gear), so who cares if you pay for more KW than you'll ever use when buying diesel, it's still costs less!
3) Since the ultimate raw source of energy is diesel for long range motoring, the conversion from heat energy to mechanical to electrical to mechanical will never be as efficient as converting heat energy to mechanical.
4) Long range motoring constitutes the largest portion of the average cruiser's diesel budget, and this is where hybrid EP is overall less efficient.
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Old 16-12-2018, 21:03   #1740
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Re: Oceanvolt Hybrid Motor

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Originally Posted by ssmoot View Post
That's... exactly what I said. I mentioned that when considering slowing down for comfort, you might use that extra power instead. No where did I suggest to change your reefing strategy.

Of course "loads will be higher". But that's just pedantry. The claim that regeneration is only 10% efficient, and that you'll be exposing your boat to dangerous loads by pulling 400w off a sail drive aren't credible assertions on their own however.
You're not the only person posting here! Bridaus said loads wouldn't change due to regen.

Anyway, it's pretty rare that I slow down for comfort. I'll reduce sail when I feel it's prudent for safety, but as far as I can recall, reducing sail for comfort..... maybe in 2012?
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