Kayak motor

Discussion in 'Boat Design' started by NikRitz, Apr 22, 2020.

  1. NikRitz
    Joined: Apr 2020
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    Location: Chania, Greece

    NikRitz New Member

    Hi all! This is my first message here. Sorry if there is something familiar around at the thread, i couldn't find, please the admin to move it if necessary.

    I am thinking of making a trolling motor with a straight shaft. I don't want to have issues with waterproofing my motor, so i will put it over the sea, at the side of the rail inside a waterproof box. I am thinking like the image i am sending. I am planning to use this 70110 brushless motor but it is out of stock for now or something similar. Of course with the right esc and speed controller and i don't know yet what battery. Generally i would like some suggestions for the parts. Do you think that my plan will work?
    https://alienpowersystem.com/shop/brushless-motors/70mm/aps-70110-outrunner-brushless-motor-100kv-3200w/
     

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  2. Blueknarr
    Joined: Aug 2017
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    Location: Colorado

    Blueknarr Senior Member

    Could and probably would work.
    Search this site for a plethora of threads dealing with "long tail outboard" or "cordless drill outboard motor"
     
  3. NikRitz
    Joined: Apr 2020
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    Location: Chania, Greece

    NikRitz New Member

    Thank you very much.
     
  4. alan craig
    Joined: Jul 2012
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    Location: s.e. england

    alan craig Senior Member

  5. messabout
    Joined: Jan 2006
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    Location: Lakeland Fl USA

    messabout Senior Member

    Search the forum for extensive descriptions of propulsion with a battery powered electric drill. That is an old thread but it may be of interest if you can dig it up again.
     
  6. portacruise
    Joined: Jun 2009
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    Location: USA

    portacruise Senior Member

    The o p link has reference to transmission kit. Small Gearing down losses might allow for a still more efficient arrangement compared to direct drive, as it might be possible to fine tune the RPM and torque to the Peak efficiency using reduction for a particular motor and prop. In the solar powered kayak motor link, the motor was only run at a maximum of around 10% of rated power, which might not be the best match of size, power and load. Hope this helps.
     
  7. NikRitz
    Joined: Apr 2020
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    Location: Chania, Greece

    NikRitz New Member

    Thank you all for your kind replies. I would like to avoid gear down, because of the noise and also i would prefer avoiding the need of water sealing. I mean i will use a ready water sealed box for the motor, esc, batteries and controller to fit, but i wouldn't mind for the shaft. Because of that i was thinking that i could just use ceramic bearings for the 10mm stainless shaft to move inside a stainless steel tube that will be strong to avoid wobbling. Also this motor i am talking isn't much kv (it is only 100) so i think that i will have rpm around the needed for that use.
     
  8. portacruise
    Joined: Jun 2009
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    Location: USA

    portacruise Senior Member

    The gear down is done with silent pulleys and timing belt, which allows easy and fast change of pulleys until the best ratio is discovered. See a Alien Drive complete kits for example. The RPMs of at least some OutRunner Motors are too high without gear down, to match an efficient prop when run at design voltage and speed. There was reference on the second link to using ventilated noise shielding on the OutRunner Motors themselves which already have a loud unpleasant noise, even without gears. Putting the four components you mention in a slightly vented or sealed box might likely cause overheating to the point of a fire hazard, as these major components generate considerable Heat. It is hard to believe, but the trailing shaft doesn't need bearings to avoid wobble, especially if it is made of spring steel where it curves and self aligns to the horizontal. Myself has been using a geared down system with flex shaft an average of once a week, for many years. But you know your own situation much better than I, so some of these ideas may not work for you. Depends on the Range, speed, portability, and other factors that you need.
     
    Last edited: Apr 23, 2020
  9. NikRitz
    Joined: Apr 2020
    Posts: 4
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    Location: Chania, Greece

    NikRitz New Member

    Dear friend, thank you very much for your advice. I don't know some of the things you suggest. I don't know what spring steel is. I was planning to use stainless steel 10mm shaft. The overheat is something i do mind. I thought if i could make a water jacket for the motor maybe i could solved some problems? Your idea with pulley gear down system is something i will surely consider. Could you please tell me something because i don't understand. If the motor is strong and i have higher rpm doesn't that take me more speed? What is the problem with having more rpm at the propeller? I was thinking that 100kv motor with 42v battery would bring me 4200 rpm. Is it too much?
     

  10. portacruise
    Joined: Jun 2009
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    Location: USA

    portacruise Senior Member

    Look at PC answers below.

     
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