Pedal Powered Boats

Discussion in 'Boat Design' started by Guest625101138, Jul 14, 2008.

  1. Sockmonkey
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    Sockmonkey Junior Member

    The streamlining on the shafts would also need a little bit of twist, like prop blades do for maximum efficiency..
     
  2. Sockmonkey
    Joined: Dec 2020
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    Location: Michigan

    Sockmonkey Junior Member

    Was messing about a bit with a paddle-wheel configuration that would always keep the paddles perpendicular to the water surface.
    Mounting them between two vertically offset wheels lets you do this, and driving both of them with belts keeps the pivoting paddles from binding up.
    [​IMG]
    Simple to build, weed-proof, and I suspect few mechanical losses.
    Sadly I've discovered a fundamental flaw in the concept.
    As the paddles are always moving in a circle rather than a straight line, the horizontal movement of them on entry and exit is slower than at the bottom of the arc.
    That means drag, and is probably a deal-breaker for most, in spite of the other advantages.
    Gonna see if I can solve it, but if I can't keep the parts count down, I'll try something else.
     
  3. Tiny Turnip
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    Tiny Turnip Senior Member

  4. Sockmonkey
    Joined: Dec 2020
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    Sockmonkey Junior Member

    Took a couple days to read through it.
    I could see a horizontal Voith drive being good for use as a combination lift/thrust unit for a powered hydrofoil type boat as you could aim the thrust down initially to get over the hump curve faster, though complexity might cause too many mechanical losses for a pedal boat.

    For shallow, weedy water, the paddle wheel with pivoting blades could be worth the slight hydrodynamic inefficiency

    I've seen various patents where people used setups like tank treads for water propulsion.
    I don't know how good something like a snowmobile track would be on a pedal boat, but you get the advantages of a big paddle wheel in a small package.
    Being weed and stump-proof is always nice.


    Here is an alternative to the twisted chain drive units.
    [​IMG]
    You still have that single crown gear, which is unfortunate.
    However driving the prop with a wide toothed belt is efficient, reliable, won't really care much if water leaks in, and lets you keep the strut fairly thin.

    I do appreciate getting responses from you guys. The newbie spouting ideas every day is rarely all that popular.
    I've been reading through this thread, and have studied various propulsion systems enough to get a handle on why things work the way they do.
     
  5. Squidly-Diddly
    Joined: Sep 2007
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    Squidly-Diddly Senior Member

    Yipes, good point but I don't think that would work because the twist would want to be on the other direction for the return stroke. Maybe that is why this idea has never been used. :(
     
  6. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    That will create a huge amount of resistance and turbulence. The blades entering the water will be at the same speed of the boat and generate no thrust. The blades exiting the water will be at the same speed of the boat and will create negative thrust because the water is moving aft faster than the boat. A system of cams to feather the blades would increase the paddle wheel's efficiency at the cost of extra weight and a lot of complications from the moving parts.
     
  7. Will Gilmore
    Joined: Aug 2017
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    Location: Littleton, nh

    Will Gilmore Senior Member

    I have not read through this thread. I have read the first post and jumped to these last few. I am interested in alternative powered propulsion systems, especially ones that don't rely upon a fuel source beyond my personal reach without a whole civilization in place to support it.
    Looking at sockmonkey's idea, I like what you're doing there.

    I will point out that the wider the belt pulley surface area that meets, the more frictional resistance introduced into the system. Racing bicycle have narrow tires to meet the road for just this reason and drag racers have extra wide tires for better grip because they have more power than their tires can transfer to the road surface.

    I have put off picking up this thread because it is so long, but I think I'd like to follow along and read back a bit to catch up.
     
    BlueBell likes this.
  8. gonzo
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    gonzo Senior Member

    One way of simplifying it is to have the crew sideways instead of looking forward.
     
  9. Sockmonkey
    Joined: Dec 2020
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    Sockmonkey Junior Member

    Don't sweat it. The ones who make progress are the ones who don't let things stop them from trying the next idea.
    Yep, that's the critical flaw I mentioned.
    It's possible to solve part of the drag problem by making the wheel conventional, and having the blades be able to fold flat in one direction with a little spring on each one holding them open like ratchet teeth do. The springs would be small, and only there to keep the blades from flopping around as they go over the top so the force of the water could easily fold the slow ones flat. You would still get a little water lifting at the rear, but not a lot.
    [​IMG]
    Heh, I've been reading this thread for a couple weeks and I'm still not done.
    I decided on that wide belt so that it can be thin without being weak so that the drive sprocket it wraps around can also be small in diameter and the faring around it can be small for less drag.
    Certainly. It would bug me, but many would be fine with it. All engineering is compromise after all.
     
    Last edited: Jan 18, 2021
  10. Will Gilmore
    Joined: Aug 2017
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    Location: Littleton, nh

    Will Gilmore Senior Member

    Have you looked into some sort of spring drive and you pedal to wind the spring?
    upload_2021-1-17_22-25-16.png
    The center of the coil would be attached to the propeller shaft, the outer end of the coil to a bull wheel that is turned by the pedals to tighten the spring. If designed well, it should be able to store pedal energy even as it expends it on the shaft. Then, it's a matter of governing the shaft speed and making sure the pedals don't go backwards. You could wind it up before leaving the dock and use a shaft break to control speed. Any way you can wind the spring would help, including wave action; like with a self-winding watch.

    -Will (Dragonfly)

    -Will (Dragonfly)
     
  11. portacruise
    Joined: Jun 2009
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    portacruise Senior Member

    http://www.humanpoweredboats.com/Photos/UniversityDisplacementHPBs/TUHHSnelda_2.jpg

    One of my favorite water wheel concept boats because it uses normally detrimental skin friction to help Propel the boat. There are other various water wheel designs pictured in this International human powered boat racing collection. Some of the records are held by air props, which have come into question because of slight Tailwinds.

    Hope this helps.
     
  12. portacruise
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    portacruise Senior Member

    Second entry on this link, another Waterwheel hydrofoil favorite. Some seem to think it might be within the range of human power, on this and other links within this forum.

    Building Hydrofoils https://foils.org/academic-papers/building-hydrofoils/

    Hydrocopter by Frances Reynolds, also uses water friction to help propulsion. Seems like I Saw something about him being involved in the Australia V ? awhile back.
     
  13. Sockmonkey
    Joined: Dec 2020
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    Sockmonkey Junior Member

    Huh, neat. I thought it was trying to do the tank-treads-as-long-paddle-wheels thing. I wonder how well it would work to have a skinny belt with a rough outer texture running nearly the full length of a fast hull just barely peeking out the bottom. Would the adhesion give you enough grip?
    There are other issues that need solving, but that question needs to be answered to know if they're worth solving.
    [​IMG]
     
    Last edited: Jan 19, 2021
  14. jehardiman
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    jehardiman Senior Member

    Before building that I would suggest finding the International Submarine Races paper by LCDR/Dr. Pat Poole, USNA, on traction drives.
     

  15. portacruise
    Joined: Jun 2009
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    portacruise Senior Member

    Sock, see note above.
     
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