Pedal Powered Boats

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

  1. Scheny
    Joined: Feb 2012
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    Location: Vienna/Austria

    Scheny Junior Member

    Currently I am forced to pause the project, as we have ordered a beautiful new living room furniture with the problem that the floor beneath is still being renewed. My wife and me are doing double-shifts to get the renovation finished before the furniture arrives, but an ending is already in sight.

    My latest testing showed that 12kph was a bit optimistic (derived from the 14m long boats) but that 10kph should be still a good value and possible to achieve. After the living room is finished, I will instantly continue building the boat.

    The chart I have posted before in #1621 is rather pessimistic in calculation, but shows how gentle drag is rising with speed. So corrected to more accurate values, the CFD calculation shows an estimated speed of 10kph too.
     
  2. joco
    Joined: Nov 2009
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    Location: ottawa/ontario

    joco Junior Member

    got a question.

    anyone as some info on a push pull way to move a kayak.?

    same way as an hobie way to move your feet push pull type...but no fins...just a prop in the back off the yak.

    i see many systems here using propel...simple bike chain systemes...but looking for less motion.just some pushing.....could be a spring action to bring back the pedal and simply bush back come back by itself.

    sorry hard to explain french here.

    joco
     
  3. upchurchmr
    Joined: Feb 2011
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    Location: Ft. Worth, Tx, USA

    upchurchmr Senior Member

    joco,

    I have not seen such a boat drive, but there have been several I have see for a bicycle. You might look at the "Stringbike" for a concept.
     
  4. joco
    Joined: Nov 2009
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    Location: ottawa/ontario

    joco Junior Member

    its abit like rowbike.....but the push pedal dont have mutch movement..and i would use cam .



    i am thinking something here.

    i dont want something big.....just anaugh to propel a kayak for a few mph on some push pedal style.

    i am sher i saw something here in the past or read something here mmmmm

    joco
     
  5. Jeremy Harris
    Joined: Jun 2009
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    Location: Salisbury, UK

    Jeremy Harris Senior Member

    If you search back through this thread you'll find mention of a push-pull pedal drive, that uses a cable to drive a shaft via a pair of one-way clutch bearings. There are also photos of it, posted by Rick Willoughby (now Guest625101138) on here.

    I don't have time to do a comprehensive search through this thread, but here's a link to a video I found of the prop drive system that uses one-way clutches and a push-push pedal system to drive a propeller: http://www.boatdesign.net/forums/attachments/boat-design/23596d1216703448-im-new-here-warren_hc.wmv and here's a link to a push-push drive: http://www.boatdesign.net/forums/boat-design/pedal-powered-boats-23345-5.html#post219124
     
  6. joco
    Joined: Nov 2009
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    Location: ottawa/ontario

    joco Junior Member

    thanks.
    Jeremy Harris

    and what do you think about this way to propel a kayak.?

    joco
     
  7. GMR
    Joined: Sep 2011
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    Location: Nova Scotia

    GMR Junior Member

    First wet test

    Hi Folks,

    So.......first wet test on Saturday morning. Jane, myself and Kevin went to Cox Lake near Tantallon where we met Bill who had paddled over to help. We put the hulls and frame parts together without incident and then clamped on the boom with all the drive train, the seat, and the sport tube that held the steady bearing bar for the prop shaft. We had the center of the main frame marked and positioned the assembly with the center of mass where we thought it should be. Right on the money, because when it was thrown in the water it was about 1 inch out of the water on the bow and stern. This was installed with duct tape, c-clamps, retchet straps etc!

    I kept one rudder and dry and installed a telescoping tent pole to the other with a ball style tie rod end. SInce this was still not long enough we duct taped a paddle to the end of the handle.. Nothing but the best.....



    The prop was an APC plastic model airplane prop ( 16 x 12) and I should have taken a picture of it before it went in the water. It is on the end of an 11 foot aluyminum shaft, 3/8 in diameter, or just under 10mm.

    52 tooth crank sprocket, to a 14 tooth sprocket on a 2:1 Miterpak right angle gear box.



    The prop is installed on a stainless steel stub shaft which goes through a Delrin block. This is bolted to a 1.5 x .125 aluminum flat bar going up to the frame. This is what I wanted to use to set the maximum depth of the prop. All the joints used 1/4-20 bolts with self-locking nuts so they could all move without falling out.



    The first thing I noticed was how easily the boat moved through the water. A very light effort with a canoe paddle would move it right allong. I started to pedal gingerly and everything worked great. However, when I used just slightly more effort I could hear the prop hitting so I went back to shore. Turns out that when pedalling, the bow in the shaft is very much exagerated and this effectively shortens the shaft which changes the angle on the aluminum flat bar. So we experimented with woving the hinge point forward but eventually ended up taking the guide off altogether. This worked great for about 10 minutes and while I was starting to push just a little, one blade snapped off the prop!! On examination we could see that the other blade was white and soft at the same location and it broke a few minutes later. by this time we were just using a loop of rope to lift the prop for shallow water. I really don't want the prop dragging on the bottom when I stop pedalling....



    I think maybe the gearbox is just too far above the surface and the blades are working too hard to try and straighten shaft when pedalling. There was more flopping of the drive shaft than I expected but this could be due to not enough of the shaft in teh water.



    Over all I was extremely happy with the first outing and now will start the refinements!
     

    Attached Files:

  8. GMR
    Joined: Sep 2011
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    Location: Nova Scotia

    GMR Junior Member

    Same text but a few more pictures at....

    gmrprojects.blogspot.com

    Glen
     
  9. portacruise
    Joined: Jun 2009
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    Location: USA

    portacruise Senior Member

    GMR:

    Very interesting, thanks for posting.

    Your prop failure was caused by prop dragging on bottom then? Unless you are using the APC electric props which are much weaker than the pattern?

    Porta


     
  10. GMR
    Joined: Sep 2011
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    Location: Nova Scotia

    GMR Junior Member

    We were pretty careful not to let the prop drag on the bottom or to be near the bottom when we started pedalling. When we examined the second blade before it dissappeared there were definite signs of fatigue. You raise a good point Porta, this may have been an electric prop. I thought I read somewhere that the electric ones were better but I will have to check the other ones I collected for testing to see what they are.
    Do you have any ideas about the drive shaft movement? You can see in the photos that almost half the shaft is out of the water.
    I didn't powder coat the frame parts because I don't really know how far I want to be off the water. And I can cut the down tubes, or even just drop the drive line tube down.
    since I don't expect to need the extension out the back.

    thanks, Glen
     
  11. upchurchmr
    Joined: Feb 2011
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    Location: Ft. Worth, Tx, USA

    upchurchmr Senior Member

    GMR,

    You might want to move the hulls in as far as you can to see if you have more beam than needed. I have a similar catamaran setup for rowing. The hulls are ~12" wide. When set at a 5'total beam there was significant wave interference. The height of the waves reached about 8 inches and there were 5 peaks trailing the boat. When I moved it out to 7' there were essentially no interference peaks.

    Lighter is better, so as narrow and low as you can reasonably get the frame is best, especially if you can avoid doubling the structure with what looks like telescoping cross beams.
    Is your structure aluminum?

    Have fun,

    Marc
     
  12. portacruise
    Joined: Jun 2009
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    Location: USA

    portacruise Senior Member

    GMR:

    The electric props are more efficient at low loads. They are thinner and thus weaker, plus the tips flex more than the gas pattern type so they lose the advantage at higher loads.

    My guess on the drive shaft movement would be inadequate stiffness in the shaft itself as well as in the flat bar guide. The miterpak is high above the water and the long length encourages a bow of the drive shaft under load, forcing the prop against the flat bar guide (which yields forward under leverage).

    Hope this helps.

    Porta


     
  13. Liighthead
    Joined: Jul 2012
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    Location: Girgarre aus

    Liighthead Junior Member

    bit off topic but still on topic, if u dont mind me butting in..
    what is the best way ( or simplest.. one that works =D ) way to have a pedal drive in a small wooden punt?

    would be nice to have a pedal system for backup/crusing :p have a plan for a plan if i can set it up .. just gotta work out bits and peices. :/
     
  14. Submarine Tom

    Submarine Tom Previous Member

    GMR,

    Fantastic, nice work.

    Ya, reduce, reduce and then simply reduce some more.

    Lower, lighter, less. Experimenting with the pontoon width would be interesting.

    Maybe run them through the band saw and make two boat with half the free board...

    More...
     

  15. GMR
    Joined: Sep 2011
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    Location: Nova Scotia

    GMR Junior Member

    Hi,

    The hulls are 10 inches wide and will support 500 pounds when they go awash. This boat will be a tandem and will have a sail (windsurfer size) and/or traction kite so I do want lots of reserve. But my plan until a few days ago was to use one hull with the same drive parts and use outriggers. But I can see now that I can go quite a bit narrower and will build another hull just for that.
    I didn't get a chance to look much at the interference wake but I will try and take some photos of it this weekend.
    I also looked at the props and I think it was an electric one. I do have some pattern props and they are certainly far stiffer.
    The frame is aluminum 6061-T6 and it isn't really telescopic but it is pinned together and does assemble with 6 inches of overlap on the tubes. Since the distance between hulls is about 6.5 feet C/C I need to be able to take it apart for storage and transport.. Tomorrow I will take the frame extensions and cut a few inches out of them to lower the frame a bit. Then I will change the drive configuration to get the gearbox lower and rider lower in the frame as well. Don't want it so that it drags in the water all the time in whitecaps.....I will also scare up a GPS so I can get some idea about speed, and weigh the complete vessel. There are a few areas that can be lightened up. Including the owner.

    Thanks for all the input! Before and now....
     
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