Pedal Powered Boats

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

  1. jehardiman
    Joined: Aug 2004
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    Location: Port Orchard, Washington, USA

    jehardiman Senior Member

    We abandoned them for submerged HPV's because the "power units" didn't like the "I thought I broke it" feeling as the pedal pressure gave way at the end of the stroke. We replaced them with "stair-stepper" units and everyone like that better as well as having better physical arrangement.
     
  2. portacruise
    Joined: Jun 2009
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    Location: USA

    portacruise Senior Member

    Elliptical sprockets are more prone to having the chain fall off on a derailleur shifting arrangement because of the non circle shape would be be my guess.
     
  3. BlueBell
    Joined: May 2017
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    Location: Victoria BC Canada

    BlueBell Ahhhhh...

    One reason high cadence works well on a bicycle is the cyclists ability to even the power delivery.
    The same can be said for clip-in pedals, not the strap variety, but the quick release "click" ins.
    When I was racing, the coach would tell us to imagine spinning, not pounding.
    The bio-pace chainrings were fine, I had a set.
    Felt very strange, broken as John says.
    I took them off and sold them.
    I like the flywheel idea but not for the weight penalty...

    Edit: I didn't have any problems with the chain falling off.
    The spring loaded derailleur had no problem taking up the slack.
     
    kerosene likes this.
  4. portacruise
    Joined: Jun 2009
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    Location: USA

    portacruise Senior Member

    Curious if the bio pace sprocket had to be aligned with a timing mark on the bike chain?
     
  5. Squidly-Diddly
    Joined: Sep 2007
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    Location: SF bay

    Squidly-Diddly Senior Member

    I had a Bio-Pace on typical MTB. Timing mark wouldn't make sense because only the front gears were Bio (normal 3 gear front) so as you'd shift the rear sprocket the chain links would "just do what they do" and average out position at any one time.

    As far as the Bio Pace itself? Seemed pretty good. Never noticed it unless I switched to regular bike and tried to notice. Not sure why its not standard. I guess the tensor roller spring gets a workout, and the lower-return part of chain goes up and down.
     
  6. SuperEDIM
    Joined: Mar 2020
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    Location: France

    SuperEDIM New Member

    Hello pedal boats enthusiasts !
    Let's introduce myself. I'm a french engineer student in mecanic, design and ergonomy, and i have a project which is to redesign a pedal boat, based on user habits and hobbies.
    After reading this topic and all your suggestions/ideas, I'm asking for you're help to answer 10 quick questions (it won't last more than 2 minutes) and, in my mind, your opinion as boats lovers is very significant.

    Here's the link for the Survey:
    Pedal boat 2.0 https://docs.google.com/forms/d/e/1FAIpQLSdbXnQfgdJvrKPxZUBjAuXaJDcfJSvCAs-PO82_OGPIQcTnnw/viewform?usp=sf_link

    If you're interesting i can post the evolution of the project here, it's just the beginning and we have 4 months.

    Thank you for this topic and for your help ;)
     
  7. BlueBell
    Joined: May 2017
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    Location: Victoria BC Canada

    BlueBell Ahhhhh...

    SuperEDIM,

    You may want to translate that one question into English...
     
  8. Squidly-Diddly
    Joined: Sep 2007
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    Location: SF bay

    Squidly-Diddly Senior Member

    looks a little too simple IMO. Looks like you need to real good leg flexibility and coordination, and the setup is a basic conventional non-sliding seat that can be used with legs if you got the skills. Also looks like you need to hold your legs up in the air for extended period. Sort of like how when you are learning to shoot a rifle it takes about 45 seconds before you discover that just holding the rifle in shooting position needs new muscles. For the foot-oars, I'd want special stirups, and some springs on the oars to help keep my legs up in the air.
     
  9. Sockmonkey
    Joined: Dec 2020
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    Location: Michigan

    Sockmonkey Junior Member

    Quick question: Since normal chains don't take well to the 90 degree twist needed to mount the prop right under the pedals, has anyone tried using a beaded cable? The thing that looks like a string of pearls. I know there's a proper name for it but darned if I can remember it.
    [​IMG]
    Bends in all directions and won't slip like a belt as the beads fit into divots in the sprocket.
     
  10. Squidly-Diddly
    Joined: Sep 2007
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    Location: SF bay

    Squidly-Diddly Senior Member

    No, but IIRC the American version of the WW2 half-track used only a couple cables to link the track shoes together and was reasonably reliable and durable, with fairly easy cable re-stretch required at intervals. So maybe should account for mild stretch of cables if beads are synchronizing with gears. The German version had real mini-axle pins like a real tank or tractor tread but in the big scheme of things was considered over built and over engineered and not worth the extra cost, considering 1/2 tracks had a pretty short life span on front lines.

    Maybe some of this stuff. AmsteelBlue.com - Best price on genuine Amsteel™ Blue Synthetic Winch Lines and Rope http://amsteelblue.com/ Liked for hammock lines due to no stretch, also takes well to length adjustment interweaving. See hammock sites for details.
     
  11. Heimfried
    Joined: Apr 2015
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    Location: Berlin, Germany

    Heimfried Senior Member

  12. Sockmonkey
    Joined: Dec 2020
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    Location: Michigan

    Sockmonkey Junior Member

    Of course. There was never any question that you could do it. I'm saying a beaded cable is a slightly better candidate for it.
    If you used a chain that could flex in two axis, you could do it without a twist like so.
    [​IMG]
    The blue wheel is just to allow for the return and spins freely.
    The green sprocket at the top is to tension it and make it wrap around enough for proper engagement.
    Apparently the type of chain I was thinking of is called a sideflex or multiflex chain.
    Multi Flex Chain | Midwest Chain http://www.midwestchain.com/content/multi-flex-chain
    [​IMG]
    They don't bend as far to the "sides" as the can up and down, but that's not a problem as long as the lesser side flexing goes around the big sprocket.
     
  13. alan craig
    Joined: Jul 2012
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    Location: s.e. england

    alan craig Senior Member

    I've often thought that a "beaded cable" (or duplex version running on conventional sprockets) would work, if they could take the torque. I've seen them used in industry but - no matter what search phrase I put into Google, nothing turns up; either they are no longer made or - does anyone have an alternative description of "beaded cable"?
    There are several twisted chain or toothed belt drives available commercially.
     
  14. KJL38
    Joined: Jun 2008
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    Location: Tasmania

    KJL38 Junior Member

    Try looking for ball chain. Ball Chain Sizes | Bead Chain Sizes | Size Chart https://www.ballchain.com/chain-sizes/
     
    Tiny Turnip and hoytedow like this.

  15. Sockmonkey
    Joined: Dec 2020
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    Location: Michigan

    Sockmonkey Junior Member

    Thanks, I was having trouble finding it too. The largest one looks suitable, but the tensile strength of 175 pounds seems a little on the low side for this application. Might have to have beads 3D printed out of tough plastic and strung on a line touching each other so there won't be any slippage.
     
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