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PostPosted: Wed Mar 28, 2012 1:29 pm 
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Tom Kirkman wrote:
Thanks - I was more interested to know if perhaps Hobie had chosen a certain prop design because it proved more efficient on their boats than the standard Torqeedo prop. If it was chosen simply as a means of having something that would fit through the mirage drive well, that's another matter (although I do understand the requirement along those lines).


Tom ..... as i said, I really don't know ....... I can only look and the pics on here and the Torqeedo site and my Torqeedo ........ mine has a different pitch and it looks very eficient if that makes any sense ......... may the Hobie Company guys can weigh in here .......


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PostPosted: Wed Mar 28, 2012 1:38 pm 
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Tom Kirkman wrote:
Thanks - I was more interested to know if perhaps Hobie had chosen a certain prop design because it proved more efficient on their boats than the standard Torqeedo prop. If it was chosen simply as a means of having something that would fit through the mirage drive well, that's another matter (although I do understand the requirement along those lines).


Tom .......... I surmised the above ....... didn't really know for sure so I called Torqeedo ....... spoke to Mary Jo ...... she said that the Evolve uses the same prop so I guess I was wrong ....... she looked it up in her parts book and said they were both the same ........ so yeah.... they use the specially designed prop .......


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PostPosted: Wed Mar 28, 2012 2:22 pm 
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The eVolve uses a Hobie designed prop... not the standard Torqeedo one. We actually found our prop to be more efficient as well as being designed to fit the drive well. It is molded by Torqeedo.

As far as American made, yes we can claim that as easily as Bassyaks. We take a supplied motor and build it into our custom mounting systems... yes, systems. The kit comes with a drive well as well as a rudder mount system (PA uses only the drivewell)

One of the biggest advantages is weight. At 16 lbs... and the battery floats. Much easier to cart around and won't sink your kayak.

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PostPosted: Wed Mar 28, 2012 6:42 pm 
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Thanks Matt ........


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PostPosted: Thu Mar 29, 2012 5:39 pm 
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Tom the prop on the 403 won't fit in the Mirage drive hole.
I also believe that the Outrunner motor on the Evolve motor is different than the motor on the 403, I think it runs on a different voltage ( the battery voltage is different) I may be wrong I just going on memory.

Tight lines
Steve


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PostPosted: Thu Mar 29, 2012 5:59 pm 
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Very good thanks.

Myself and another kayak fisherman have recently machined a prop that we believe will allow common trolling motors (Minn-Kota and Motor Guide) to achieve greater speeds when used on lightweight craft such as kayaks. The props offered now are intended for use in boats weighing many hundreds of pounds. There is absolutely no reason why a 55 lb thrust Motor Guide motor won't push a common fishing kayak 10 MPH. You just need the right prop. The power is there, but even at full no-load speeds, the current props offered won't do it.

It's been another fun project and the statement here about the difference in the props interested me. Nobody, other than perhaps Torqeedo, is making kayak specific trolling motors. They should be a bit ahead in prop design for these type craft. Maybe.


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PostPosted: Thu Mar 29, 2012 8:14 pm 
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Steve ....... When we compared the engines we couldn't tell the different except that the older Evolves that we had had the 402 engines and the older batteies. I would think the new Evolves would have the new 403 engine and the new more powerful batteries ......... I waited to get the 403


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PostPosted: Sun Apr 01, 2012 4:41 pm 
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Your not going to able to tell just by looking at them, the windings are different, I may be wrong.
We have a machined aluminum three bladed prop which has very short, sharp, blades which has a higher top end but the thrust lag at lower speeds is annoying, that's why the variable pitch is the way to go. With looking for 10 mph your going to be looking at around 45 % slippage , not too efficient. The motor will have to turn a much higher RPM to use a small diameter prop, needed for clearance, I don't want a 12x12 monster 2 bladed prop
Tom the prop isn't the problem, the hulls can't handle the speed, the bow continues to rise trying to get on plane, but the back of the kayak is sinking, the tankwell is filling with water.
I was playing around with the larger motors (70 thrust)on the Malibu Stealth 12 and around 8 mph the tankwell is full of water.
It's going to be very hard to get great low end drive ability for slow maneuverability and great top end with the same prop.
There's a good post on KFS about playing with props and slippage.

Tight lines
Steve


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PostPosted: Sun Apr 01, 2012 5:26 pm 
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Steve,

We can get 10MPH with a small outboard and didn't have the problem you mention, so the hull isn't the problem. Getting the correct pitch on the prop is. The trolling motors available today were not designed for use on lightweight craft like kayaks. They have the power, but not the right prop.

We messed around this weekend and managed 7MPH with a home-made prop. We'll do even better next weekend.


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PostPosted: Mon Apr 02, 2012 8:09 am 
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I can get 7mph now if I crank the torqeedo to max AND peddal like crazy at the same time.
The hull gets very inefficient the faster you go.


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PostPosted: Mon Apr 02, 2012 8:18 pm 
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GAZ wrote:
I can get 7mph now if I crank the torqeedo to max AND peddal like crazy at the same time.
The hull gets very inefficient the faster you go.


What do you mean by inefficient? Are you speaking about steering and tracking, or are you referring to hull slap?

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PostPosted: Tue Apr 03, 2012 9:01 am 
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redgrappler wrote:
GAZ wrote:
I can get 7mph now if I crank the torqeedo to max AND peddal like crazy at the same time.
The hull gets very inefficient the faster you go.


What do you mean by inefficient? Are you speaking about steering and tracking, or are you referring to hull slap?


Hull effeciency is the ratio of applied motive force to hull speed.
At very low speed you can double the engine power output and go twice as fast but when the speed is already fast, doubling the power may only increase speed 10%.


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PostPosted: Tue Apr 03, 2012 9:19 am 
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GAZ wrote:
redgrappler wrote:
GAZ wrote:
I can get 7mph now if I crank the torqeedo to max AND peddal like crazy at the same time.
The hull gets very inefficient the faster you go.


What do you mean by inefficient? Are you speaking about steering and tracking, or are you referring to hull slap?


Hull effeciency is the ratio of applied motive force to hull speed.
At very low speed you can double the engine power output and go twice as fast but when the speed is already fast, doubling the power may only increase speed 10%.




Ahhh thanks! I should have paid attention in hydrodynamics :) Or better yet taken the class :)

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PostPosted: Tue Apr 03, 2012 12:36 pm 
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Hull speed (knots) = 1.34 x square root of waterline length (in feet)


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PostPosted: Tue Apr 03, 2012 1:16 pm 
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There is no such limit. The boat will continue to travel faster until and unless you can no longer keep it going in a straight line.

The formula you offer would limit the PA to no more than about 5MPH, and several of us have pushed them much faster than that. My current PA can do 6.3 MPH on a calm water day.


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