Pedal Powered Boats

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

  1. portacruise
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    portacruise Senior Member

    I don't know the Hobie specifically (just threw it out there for ideas), but there are tough inflatables that would consider rebar and log jams small work. Inflatables are used for survival rafts and class V rapids and extreme rescue power boats because they can take shock and puncture hazards without throwing out the riders or breaking in half. Something custom built with kevlar, along the lines or the 18' Aire sea tiger might do well, even with a speed handicap, at least one is more likely to finish.

    The outriggers and structure on the V14 would have to be beefed up. This is a great clear water boat; but supply storage, draft and portage would be issues.

    JMHO, FWIW.

    Porta

    http://www.riverboatworks.com/category.wml/categoryid/17522/RiverboatWorks-com/Jacks-Plastics.htm (under kayaks)

     
  2. spidennis
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    spidennis Chief Sawdust Sweeper

  3. joco
    Joined: Nov 2009
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    Location: ottawa/ontario

    joco Junior Member

  4. jg451
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    jg451 Junior Member

    A quick question . Some years back I remember seeing a report about a Japanese bicycle firm working on an up/down pedal motion. It might also have been a shaft drive. Anyone else? It still doesn't get us the 90 Deg. turn to propshaft. but it did go from straight line to rotary motion. Then again if it were a world beater, We'd be up to our necks in Jap pump bikes by this time.

    Jon
     
  5. jg451
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    jg451 Junior Member

    MR. Harris,
    I understand the need for power w/drive vs. finer pitch for speed w/ generation. Could that not be done with a variation on a controllable pitch prop that had, say, only two positions? Power or gen? Or does it mean a more subtle curvature to the blades than simply pitch to realize efficiency in each mode?

    Thanks
    Jon
     
  6. portacruise
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    portacruise Senior Member

    The treadle powered bike concept preceded the era of chains:

    http://en.wikipedia.org/wiki/File:Jaray-Rad_mit_Schwingpedalen_-_Verkehrszentrum.JPG

     
  7. jg451
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    jg451 Junior Member

    To Portacruise,

    Most interesting, if a little short on detail mechanics. In examining the photogaph it appears that this concept is an articulated frame bike where both feet are pressed at the same time. Push out the front wheel then let the rear catch up utilizing locking or directional hubs Quite a syncopated gallop down the road. No wonder we're not up to our necks in these either.

    Somehow the japs were using a vertical ,left/right and getting rotary shaft moment out of it. That would make it germain. Rotary to a twisted chain is all well and good, I accept that. However, a form of piston(foot), to crankshaft, to flywheel(big end gear), via straight chain, to small end gear(prop) in horizontal pod seems a viable alternative. Just thinking the kinks,

    Thanks,
    Jon
     
  8. joco
    Joined: Nov 2009
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    joco Junior Member

    look likea push only bike..you push and it come back mecanicly push again turn motuion type.mmmm

    good lick...yes a little video would be cool.

    joco
     
  9. Jeremy Harris
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    Jeremy Harris Senior Member

    You can make a modest difference by just changing the pitch, but ideally you need a bigger swept area for the generating prop in order to improve its ability to generate power from the flow through it at sailing speeds. Ultimately, you can only extract as much energy as there is available in the volume of water flowing through the prop disc, so 'bigger is better'.
     
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  10. jeanfreau
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    jeanfreau New Member

    Does anyone know where I can find a reasonably priced "roller clutch". It needs to be left-hand rotation, 5/8" bore and handle about 60 ft lbs of torque. Unfortuately all bicycle freehubs are right-handed. Can anyone help?
     
  11. Jeremy Harris
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    Jeremy Harris Senior Member

  12. Choosethisday
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    Choosethisday Junior Member

    Hey everyone, I have been working on a leg powered catamaran. The hulls and tramp are pretty much done but now I need to start working on some sort of drive unit. A down and dirty way to do it would be to modify a Hobie Mirage unit with an extension to reach the water while still being well above the waves. I do have the skills and such to make this modification but from my readings here it seems the Mirage is not all that efficient. Does anyone know if this is a systemic issue with the drive or is this a function of the way the drive is used with the the hull? From the videos of the drive in motion it appears it is just a oscillating, bidirectional, varible pitch flexible prop with a reasonable diameter. So what is it that supposedly makes this drive only about 38% efficient when a comparable diameter unidirectional is closer to 90%? Can anyone help? Thanks
     
  13. hoytedow
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    hoytedow Carbon Based Life Form

    I just wanted to say thank you to Rick Willoughby who started this thread, from whom I learned a lot.
     
  14. I57
    Joined: Feb 2008
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    Location: Melbourne, Australia

    I57 Senior Member

    Catamaran

    Choosethisday
    With your catamaran maybe one solution is with a twisted chain drive leg. You can make your own or buy one, have a look at the posts by Tiny Turpin how he has the catamaran setup. Other way is a flexible steel shaft with a right angle gear box and bike crank.
    I've been on holidays doing the grey nomad touring around the country bit and seen that Rick has left the forum. He has been a great mentor for a lot of us, certainly put me on the right track with these boats.

    Ian
     

  15. Choosethisday
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    Choosethisday Junior Member

    Ian, I have considered the twisted chain and or twisted belt setup, and the right angle drive idea. Obviously all of these work. I have some machining experience and I have actually come up with a parts list for the three as well. However, my primary goal is not speed but an long distance day cruiser with minimal setup and launch hassels. The bent shaft is perhaps the fastest but the long shaft adds considerably to the lack of portability. The twisted drive systems are OK for that but to buy a new one is costly and to build one is very time consumming, and still somewhat costly. I believe I could modify the Mirage in a reasonably short time with fairly minimal cost. But then if it really is as much less efficient as has been suggested it may not be the best way to go. So what I would like to find out is if anyone knows why the Mirage is less efficient. It may be that on a different hull/s it may work well enough.
    Thanks again
     
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