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  #1966  
Old 08-30-2014, 12:50 PM
jehardiman jehardiman is offline
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Quote:
Originally Posted by Yobarnacle View Post
Here is a youtube of interest and the quote is the blurb beneath the video.
https://www.youtube.com/watch?v=8I-H47uuQF0

"Uploaded on Oct 14, 2010
Testing a 40lb trolling motor on a Cobra Fish N Dive kayak. The first bit of footage shows use with the standard propeller and the second bit (final 25%) shows use with an 10 x 4 model aircraft propeller. We tested the standard prop as well as 3 other props of varying pitches. The standard prop gave a top speed of around 8km/h and drew 33 amps whilst the aircraft prop that came out in front gave a top speed of around 10km/h and drew 29 amps. The other pitches (10x6 and 10x8) gave slightly better speed but used too much power.
That is exactly as expected given the displacement/ length of the hull and design rational of a trolling motor. I also bet the 10x4 took longer to accelerate the boat...which is the exact opposite of the design goal of a trolling motor. There are so many nuisances to propeller design, especially when working on HPV which are such a small scale where you are not running up against practical limits (such as root bending and submergence drafts). Going to an 11x3 would most likely lower the amps even further for that speed.
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  #1967  
Old 08-30-2014, 01:23 PM
portacruise portacruise is offline
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TC:

The MK speed control claim to go 5X longer needs to be qualified for a particular low speed. The mechanical switch system of cheaper motors is slightly more efficient at FULL speed, where most troll motors are used for the greatest time...

There is also somewhat of a myth about motor cooling with a submerged troll motor head which only cools the field magnets directly. This is because of the insulating air gap between the centrally located hot armature and brushes doesn't allow for efficient cooling. Better to go with an electronically commutated outrunner motor for efficiency and cooling....

We may be getting off topic here, so perhaps should move to the electric boat thread?

PC

Quote:
Originally Posted by TomCat58 View Post
portacruise: Thank you

Yes any drag effects the performance so I design the pontoons to barely touch the water on just the rear sections while cruising. As the need increases the pontoons use more of there surface to stabilize.

The trolling motor is very affordable and yes not so efficient but with a limited budget its working ok. I did however buy one of the newer Minn Kota's that claim to go 5x longer then some of their other cheaper models. It has a computer control board using a pulse system. The other factor is the trolling motor is almost water proof. Everything on this canoe has or will get wet sooner or later. The trolling motor has come off once while the boat was tied up on a sandy shore. I got it out of the 2 feet of water and dried it the best I could and it works just like new :-)

Thank you for your comments I am on a constant learning curve to improve my canoe. The next improvement I think I will make is to replace the two 29 series deep cycle batteries with Lithium Lifepo4 electric car type batteries.

That improvement from my research promises to greatly improve speed and extend how long the batteries last.

TomCat
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  #1968  
Old 08-31-2014, 09:02 PM
TomCat58 TomCat58 is offline
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Electric boat thread ?

PC,
Yes your correct this has gotten off topic here. Where should I post at to keep it going?

I am trying to move this thread to the electric boat thread but am not having any luck finding it. I see gas powered, diesel powered but no solar or electrical powered ?

Thanks
TomCat
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  #1969  
Old 08-31-2014, 10:08 PM
TomCat58 TomCat58 is offline
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OK this thread has been moved to:


http://www.boatdesign.net/forums/boa...gns-19444.html

Small boats and Solar Power
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  #1970  
Old Yesterday, 09:05 PM
P Flados P Flados is offline
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The link above should have been Small boats and Solar Power
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  #1971  
Old Yesterday, 10:55 PM
TomCat58 TomCat58 is offline
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Thank you Flados..... I am still trying to figure out this forum and how it functions..
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  #1972  
Old Yesterday, 10:59 PM
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Yobarnacle Yobarnacle is offline
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Originally Posted by TomCat58 View Post
Thank you Flados..... I am still trying to figure out this forum and how it functions..
Me too!
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  #1973  
Old Today, 01:27 AM
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Leo Lazauskas Leo Lazauskas is offline
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Quote:
Originally Posted by jehardiman View Post
And that is for dead flat calm, so add 20-30% seaway margin for real conditions. 74-79 watts is ~ 1/10 Hp sustained, which is approaching serious amateur cyclist ability.
I'd also add a bit more if the hull isn't going to be kept very clean.
And more for any appendages, especially if they aren't filleted well.
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