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Old 20-11-2016, 02:54   #391
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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?
Of course! It's all about applicable traction in this case, which has little to do with HP

Quote:
HP is HP, Power is Power, regardless of the method of providing it.
Yes it is, but only if it can be applied. That John Deere used most of it's power churning up the ground rather than in pulling the steam tractor.

Try the same exercise on a hard rough surface where both tractors can get reasonable traction. Or at least use the old off-road trick for sand/mud driving of deflating the John Deare's tyres so that they have greater contact surface area with the ground.


You really don't understand basic physics at all, do you.
(And you don't seem to be interesting in learning, either)
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Old 20-11-2016, 03:02   #392
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Re: Oceanvolt Hybrid Motor

Quote:
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?

HP is HP, Power is Power, regardless of the method of providing it.
Traction!!

On that ground, one of these would probably easily outpull either of those tractors:

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Old 20-11-2016, 08:15   #393
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Re: Oceanvolt Hybrid Motor

Quote:
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?

HP is HP, Power is Power, regardless of the method of providing it.
Only if you kept the length and angle of the towing cable the same as in the video, and your 18 HP petrol had the same longitudinal and vertical center of gravity in relation on the position of it's pulling wheels contact area with the ground.
If you watch the video again and pay attention, you will notice the cable was always far from being horizontal, it was always pulling the John Deere up, and the steamer down, hence increasing traction for the steamer and reducing traction for the diesel tractor.
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Old 20-11-2016, 08:18   #394
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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?

HP is HP, Power is Power, regardless of the method of providing it.
If the 18hp petrol tractor had equal or better traction and a deep enough gear ratio...YES!!!!!:banghea d:

This is what I was trying to get thru when I compared a 40hp tractor vs a 400hp Ferrari. The actual engine on the Ferrari has more HP and likely more torque but the transmission isn't geared to provide low speed torque to the wheels and the wheels aren't designed to get traction on loose soil.

Another analogy would be who can lift more...an Olympic level weight lifter or a sickly 10yr old girl. I can set up a test where the 10yr old girl will win which would have a similar effect to your "thrust" comparison:
- Weight lifter walks up to the barbell and simply lifts.
- 10yr old girl gets to use a pulley system with a 50-1 ratio.

At the upper limit, the 10yr old girl is going to lift far more. Any sane person would cry foul that it's not an equal test...same as putting a larger low pitch prop designed for thrust on an electric motor while leaving the diesel with the standard gear ratio and prop for normal cruising.

BUT!!!!....if you set the weight at the upper limit of the weight lifters capability, you will find the weight lifters greater HP/KW will allow him to lift that weight many times faster than the 10yr old girl can lift the same weight.

If the issue really was static thrust, manufacturers would simply supply a transmission with a deeper gear ratio to boost torque at the prop shaft and then use a big low pitch prop. (this is the primary difference between tractor and car transmissions by the way.)
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Old 20-11-2016, 12:00   #395
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Re: Oceanvolt Hybrid Motor

One man’s experiment with electric propulsion – La possibilità di un'isola
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Old 20-11-2016, 14:26   #396
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Re: Oceanvolt Hybrid Motor

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Originally Posted by Just Another Sa View Post
Only if you kept the length and angle of the towing cable the same as in the video, and your 18 HP petrol had the same longitudinal and vertical center of gravity in relation on the position of it's pulling wheels contact area with the ground.
If you watch the video again and pay attention, you will notice the cable was always far from being horizontal, it was always pulling the John Deere up, and the steamer down, hence increasing traction for the steamer and reducing traction for the diesel tractor.
Oops, missed that point - but you are spot on!
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Old 20-11-2016, 18:10   #397
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Re: Oceanvolt Hybrid Motor

He makes some very good points that are not often discussed. Particularly his observations in "Electric Propulsion Makes Better Sailors" section where seamanship may be used instead of diesel brute force. It's all too easy to extrapolate driving a boat from driving a car where you assume the mindset of "I can go where ever I want, whenever I want, at whatever speed I want. (hopefully within some limits on that one)

So instead of bashing into weather, maybe there's also a nice destination just over there on a reach. Maybe the prudent course of action might even be to turn around and wait it out.

There are a few (not many) limitations for EP, and for those who want EP to be exactly the same as having diesels, consider how having fixed ideas about schedules and destinations might be part of the problem.
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Old 21-11-2016, 03:12   #398
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Re: Oceanvolt Hybrid Motor

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Originally Posted by BigBeakie View Post
He makes some very good points that are not often discussed. Particularly his observations in "Electric Propulsion Makes Better Sailors" section where seamanship may be used instead of diesel brute force. It's all too easy to extrapolate driving a boat from driving a car where you assume the mindset of "I can go where ever I want, whenever I want, at whatever speed I want. (hopefully within some limits on that one)

So instead of bashing into weather, maybe there's also a nice destination just over there on a reach. Maybe the prudent course of action might even be to turn around and wait it out.

There are a few (not many) limitations for EP, and for those who want EP to be exactly the same as having diesels, consider how having fixed ideas about schedules and destinations might be part of the problem.
It's all very consistent with what people have been telling you. If you accept drastically reduced capabilities (he reported 15mile range at 3kt cruise speed), you can do electric now.

The vast majority of cruisers aren't interested in halving an already low cruise speed while cutting range to little more than enough to get in and out of the marina.

It's when you try to claim the same or "equivalent" capability that the facts don't support you.
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Old 21-11-2016, 04:10   #399
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Re: Oceanvolt Hybrid Motor

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Originally Posted by BigBeakie View Post
There are a few (not many) limitations for EP, and for those who want EP to be exactly the same as having diesels, consider how having fixed ideas about schedules and destinations might be part of the problem.
I missed the part where diesel has a problem that EP can solve. Can you go back and restate the problem for me?
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Old 22-11-2016, 06:41   #400
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Re: Oceanvolt Hybrid Motor

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I missed the part where diesel has a problem that EP can solve. Can you go back and restate the problem for me?
Haha I think that sums up the state of the art quite well.
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Old 22-11-2016, 07:05   #401
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Re: Oceanvolt Hybrid Motor

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I missed the part where diesel has a problem that EP can solve. Can you go back and restate the problem for me?
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"
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Old 22-11-2016, 08:05   #402
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Oceanvolt Hybrid Motor

It is a fair assumption that the primary EP proponents have had little experience with real world application of the tech. If they insist on believing the hype there is not much that can be said that can dissuade them.

Many start on a cruising life with little experience and big dreams. They have never been at the mercy of high winds, no wind or adverse currents with only a sail and inadequate aux propulsion. Never been in a tight, busy ship channel and had a 50mph beam wind to suddenly to deal with and know the feeling of gratitude towards the builder that recommended an engine more than capable of driving the boat.

I try to coddle my old 4-154. It will sip fuel and push the boat quite well at low rpm, but when the need arises, and it has, it will make the stern squat and the bow turn in a tough situation.

If you insist on installing an unproven15 hp motor rather than a 40 hp engine, someone will gladly sell it to you. If your home breaks up on the rocks and your looking for someone to blame, grab a mirror and blame away.
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Old 22-11-2016, 08:30   #403
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Re: Oceanvolt Hybrid Motor

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Originally Posted by Cap Erict3 View Post

If you insist on installing an unproven 15 hp motor rather than a 40 hp engine, someone will gladly sell it to you. If your home breaks up on the rocks and your looking for someone to blame, grab a mirror and blame away.
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.
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Old 22-11-2016, 09:02   #404
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Re: Oceanvolt Hybrid Motor

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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.
Please enlighten us on the "proper calculations" that make electric HP magically out perform a diesel with 3 times HP (One of the claims was a 15hp electric could match the performance of a 45hp diesel.)

(FYI - you might want to look at the posts that had videos of tractor pulls before setting yourself up.)
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Old 22-11-2016, 09:08   #405
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Re: Oceanvolt Hybrid Motor

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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