Small boats and Solar Power

Discussion in 'Boat Design' started by TomCat58, Aug 31, 2014.

  1. TomCat58
    Joined: Dec 2013
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    Location: Washington State

    TomCat58 Junior Member

    I and a few others making some interesting post on alternative power for small boats and then realized we were high jacking a thread.

    So I start a new thread in hopes of some interesting post about solar and canoe or other small vessels.

    Here is were I am at with my project so far and there were some good post on hull speed, changing to different props etc. So jump right in with your ideas on improving efficiency, increasing power, reducing amperage draw, battery types or any other ideas I can apply to my project or someone else finds interesting and can use.

    https://sites.google.com/site/serenitysolarcanoe/

    https://sites.google.com/site/serenitysolarcanoe/home/short-videos-from-serinity


    TomCat
     
    Last edited: Aug 31, 2014
  2. Yobarnacle
    Joined: Nov 2011
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    Location: Mexico, Florida

    Yobarnacle Senior Member

    TomCat. You might consider tweaking your trolling motor.
    It's often repeated the propeller/motor combo needs to match the boat.
    If the boat and motor are rigid constants, leaves changing props as only available adjustment.
    Trolling motors weren't intended for cruising. Why not? It's a motor. Comes back to the prop.
    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.
    Next job is to further cut down the shaft of the motor as optimal depth has been discovered and then set about installing a spinner to increase efficiency."

    Appears this experimenter gained 25 % more speed and reduced amps by 12% (longer battery hours) using the model airplane prop.

    There is a very informative thread this forum, on tweaking various aspects of trolling motors.

    Over-Volting a DC Motor

    The upshot I gleaned is, more volts is fine but too many amps may fry the controller. Reducing propeller drag is needed to reduce amps. The airplane prop evidently reduces drag and amps.

    You can consider increasing volts and speed once you reduced amps.
    Again, the limitations are in the controller more than the water cooled motor.

    Can the minn kota controller withstand higher voltage?
    I include below a screen shot of this site.

    http://www.northlandmarine.com/MinnkotaRiptide.html

    You will notice the red boxed (my doing) controller is the same part for both 24 volt and 36 volt models. My guess , yes can withstand up to 36 volts no problem.

    Using lower pwm throttle setting to run at same cruising speed (benefit of higher volts) should reduce amp draw further. and you have a higher top speed in emergency for a short duration.

    Among the great suggestions in the thread above, is install an amp meter in plain view to monitor your amps.
    I fried a minn kota pwm controller using a 5 bladed seagull prop on a trolling motor. I think that was the problem since amps gives torque and volts rpm, I believe the torque that prop required drew too many amps.

    Interesting project, thanks.



    __________________
    :D "The Titanic was the finest ship afloat, ten minutes before it encountered Reality. "
     

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  3. Yobarnacle
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    Yobarnacle Senior Member

    Okay. I deleted this big post on the other thread after copying to here. Hope everybody is happier
     
  4. portacruise
    Joined: Jun 2009
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    portacruise Senior Member


    Ok, thanks for starting this thread.

    Sorry, I just missed your earlier post, I was in a hurry, and wrote the incomplete title. In hindsight, I should have mentioned about the search function. Most of the improvements you might be interested in can be found under author: portacruise or whoever's contributions you want, and reading the surrounding posts by other authors as well. Sort by thread and title especially in the efficient electric boats thread. This approach works on most forums I use, even those not related to boats.

    Your motor efficiency is low:

    If you are interested in building your own search for Jeremy Harris and other good nearby author posts on this forum and on http://endless-sphere.com/forums/viewforum.php?f=39&sid=490026d02a4dcfd1b3f87579b6e571ed

    If you just want to tweek a TM for best efficiency go here: http://www.boatdesign.net/forums/boat-design/efficient-electric-boat-27996-17.html post #252.

    If you just want to buy: Torqeedo is supposed to be state of the art for the submerged head type but noisy: http://www.torqeedo.com/us/electric...with-integrated-battery-for-kayaks-and-canoes

    I like homemade geared down trailing shaft motors, turning large slow moving props, which are generally more efficient across the board. http://www.rickwill.bigpondhosting.com/V4_Electric.htm

    Your windage might be a consideration:
    Your videos show glassy smooth water conditions in fairly open water. If you expect to encounter rough wind and waves you may not be able to fight your way into it. If you mount your cells lower, that would help-but you will lose your shade.

    Pc
     
  5. Yobarnacle
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    Yobarnacle Senior Member

    https://www.youtube.com/watch?v=wSZGUV8D19I

    I'm planning to explore this technology. I have so many projects underway, this will be postponed to the winter months. Mirrors will increase the winter sunlight to near summer values for testing.
     
  6. Rastapop
    Joined: Mar 2014
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    Location: Australia

    Rastapop Naval Architect

    An air propeller is not suitable for water. It's been specifically designed for a fluid 1/1000 of the density, that's compressible, and for an rpm far greater than you're likely to use in water.


    This is incorrect.
    You can sit at any point on the motor's rpm/torque curve simply by altering the gearing.
     
  7. Yobarnacle
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    Yobarnacle Senior Member

    Did you watch the youtube?

    as to my burnt controller,
    I was using two 5 bladed 11 inch dia, 10 inch averaged pitch, Seagull alloy Hydrofan props on a double engine mount Minn Kota trolling motor pair. 2 HP each.
    24 volt pwm controller that my batteries fed 30 volts +/-.

    After about 100 hours of testing over several weeks, controller smoked and died.
    Any idea why?
    Not hijacking here. I would like to know so I don't offer wrong ideas to folks like TomCat.
     

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  8. portacruise
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    portacruise Senior Member

    Ok, this is not a solar or thermocouple cell, but a poor example of a simple primary battery like the disposable cells you buy for flashlights. It would show a voltage reading even in the dark and cold. The inner surface of the more active metals Al, Zn, would be oxidized if any significant power is drawn from the cell at which point power delivery would stop. A voltmeter will show a reading because is draws such tiny amounts of current. You can observe the same effect if you immerse any two dissimilar metals in a suitable electrolyte, or even insert them into a lemon, etc. often used as a chem demo.

    Hope this helps

    PC
     
  9. portacruise
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    portacruise Senior Member

    Hope comments above help.

    PC
     
  10. portacruise
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    portacruise Senior Member

    Hope this helps.

    PC
     
  11. Yobarnacle
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    Yobarnacle Senior Member

    "PC: Your props might well be drawing power that exceeds the design of the controller. Also there are peak load power spikes and maybe a back emf effect when starting and stopping. Five wide blades have extremely high water resistance profile and will draw a lot of power (amps) at the same pitch and diameter compared to the equivalent narrow 2 blade."

    That is my estimation also. Pulled too many amps as battery volts decreased..

    The 5 blade props produced enormous low speed forward thrust WHILE it worked. They were shrouded also (nozzles).
    Crappy in reverse though. thanks
     
  12. portacruise
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    portacruise Senior Member

    overvolting troll motors

    From YB:

    Over-Volting a DC Motor

    The upshot I gleaned is, more volts is fine but too many amps may fry the controller. Reducing propeller drag is needed to reduce amps. The airplane prop evidently reduces drag and amps.

    You can consider increasing volts and speed once you reduced amps.
    Again, the limitations are in the controller more than the water cooled motor.

    Can the minn kota controller withstand higher voltage?
    I include below a screen shot of this site.

    http://www.northlandmarine.com/MinnkotaRiptide.html

    You will notice the red boxed (my doing) controller is the same part for both 24 volt and 36 volt models. My guess , yes can withstand up to 36 volts no problem.

    Using lower pwm throttle setting to run at same cruising speed (benefit of higher volts) should reduce amp draw further. and you have a higher top speed in emergency for a short duration.

    Among the great suggestions in the thread above, is install an amp meter in plain view to monitor your amps.
    I fried a minn kota pwm controller using a 5 bladed seagull prop on a trolling motor. I think that was the problem since amps gives torque and volts rpm, I believe the torque that prop required drew too many amps.

    PC: Too many amps will also fry the motor at some point (stall, etc), even with a heavy duty external controller that you add yourself as in the efficient electric boats post above. Electronic controllers have voltage and amps ratings which should not be exceeded though there is generally more leeway on the volts. A built in unsealed controller is generally the weakest link as any troll repairman will tell you (moisture, corrosion, overload, etc.). Typically weed or debris tangles in the prop so that it slows or stalls and the amps skyrocket to burn the controller. Dangerous if you are stranded in rough conditions or remote places because it is hard to jumper a limp home mode quickly, unlike the cheaper resistance switch type- which I preferred. A smaller prop with a lower pitch can be picked so that even at full throttle, the amps rating is not exceeding the max. If things slowed a bit I monitored the amps when using trolls to make sure they were not over limit from a tangle or headwind. I ran a 12V TM at 24V with a series/parallel switch (2- 12v batt) and later an external controller in weekly use for over a decade this way and it still works. I haven't used it for many years, but disassembled the motor at the end of that period and there was essentially no wear on the brushes, windings or bearings from what I could tell. The motor looked to be inefficient (front bushing at that time, rear ball bearing), standard, off the shelf type with 3600 rpm ratings. Essentially this same motor is used today as it appears from your posted parts list, (also with all the other standard old brands) which continue to hype "5X" controllers when upgrading to a newer brushless outrunner motor designs would make a much bigger difference. The 12v rated troll motor runs at about 1200 rpm @ 12v under load, so even at 24v (double power and rpm), 2400 is way below where the windings might pull out from overspeed.

    Hope this helps, FWIW category.
     
  13. Yobarnacle
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    Yobarnacle Senior Member

    TomCat.
    If you use the aircraft props, a shroud will protect tips and protect people and aquatics from the spinning tips and may improve thrust, but increases drag.
    Everything is compromises.
     
  14. Yobarnacle
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    Location: Mexico, Florida

    Yobarnacle Senior Member

    Thanks PC.
    I have been studying "newer brushless outrunner motors" for some months. I watched youtubes of them running submerged. You can even buy them manufactured with cooling water jackets and in/out water connections. Using as trolling motors, only their very high RPMs seems an obstacle.
    Two power enhancements I have NOT seen tried, but should work, is:
    1# Bolting two outrunners together nose to nose, with a propeller trapped between them. A prop shroud could bridge and incorporate the two mounting struts for rigidity.
    2# The 2nd untried option, is mounting an outrunner in place of the rotor inside a larger inrunner electric motor. The magnet bearing outrunner shell would spin between the stator coils in the center, and the peripheral coils lining the outermost motor housing.
    My gut feeling suggests considerable torque could be obtained.
    Some economies as well if the inner and outer coils could be separately switched in/out of circuit. and might even have motor/gen applications.
     

  15. TomCat58
    Joined: Dec 2013
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    Location: Washington State

    TomCat58 Junior Member

    This looks like a good way to compare batteries, trolling motors, props etc.

    http://tufox.com/hobie/TrollingPerformance.html

    TomCat
     
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