Pedal powered dinghy works at last

Discussion in 'Boat Design' started by Andrew Kirk, Jul 13, 2021.

  1. Andrew Kirk
    Joined: Jul 2021
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    Location: Chorley UK

    Andrew Kirk Junior Member

    I’m still working on the boat. I did 2 miles yesterday at an average of 3.3 mph, according to Strava. I’m trying to make the pedal action smoother by getting the length of the connecting rods perfect. Then I think I’ll be right up to maximum hull speed at a fairly easy cycling effort. The best development for speed might be a long catamaran but speed isn’t my only goal. I’d be interested to hear any ideas, though.
     
  2. Andrew Kirk
    Joined: Jul 2021
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    Location: Chorley UK

    Andrew Kirk Junior Member

  3. bajansailor
    Joined: Oct 2007
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    bajansailor Marine Surveyor

    Andrew, I think that your video might be for your 'friends only' - as I am logged in to FB but when I click on your link I simply get :

    'This content isn't available at the moment
    When this happens, it's usually because the owner only shared it with a small group of people or changed who can see it, or it's been deleted'.

    Can you perhaps change the setting from (I presume) 'friends only' to 'public'?
     
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  4. Tiny Turnip
    Joined: Mar 2008
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    Tiny Turnip Senior Member

    Andrew, if you can bullet point what you would like from the boat, where you are planning to use it and so forth, it will help folk offer focussed advice.
     
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  5. Andrew Kirk
    Joined: Jul 2021
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    Location: Chorley UK

    Andrew Kirk Junior Member

    I've now improved the pedal action of my boat and got it smooth. I can feel the 6 paddles kissing the water and I'm getting a good cruising speed. I might replace the long rods which connect the pedals to the paddle wheel because it was flexing in the rods which caused a notchy feel to things. Since I can get up to around hull speed I really don't see a need to change the propulsion system except to make sure it's reliable. It's been great to get such positive reactions from everyone I meet, on foot or on boats, as I sail down the canal. Below is my son trying the boat. He needs more leg room than I do.
    https://mountainbikerhome.files.wordpress.com/2021/07/img_20210716_140021.jpg?resize=668,668 dylanboat2.jpg
     
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  6. BlueBell
    Joined: May 2017
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    Location: Victoria BC Canada

    BlueBell "Whatever..."

    Andrew,
    I'm glad you said "calculated" as it's not a finite value, which means two decimal places is kind of silly.
    BB
     
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  7. portacruise
    Joined: Jun 2009
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    Location: USA

    portacruise Senior Member

    Speed measured with GPS might have big errors because wind and/ or current is not taken into account? So a GPS readout of 3 miles per hour might have a range of plus or minus 1 mile per hour when I ran the identical course, but in the opposite Direction, with my lightweight 25 lb boat +rider. Heavier boats might not be affected as much percentage wise? I got better accuracy with a drag behind knot meter, which would presumably correct for current, but not wind.
     
  8. BlueBell
    Joined: May 2017
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    Location: Victoria BC Canada

    BlueBell "Whatever..."

    Or just turn around until you get a stable reading and split the difference for a more accurate figure.
     
  9. Andrew Kirk
    Joined: Jul 2021
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    Location: Chorley UK

    Andrew Kirk Junior Member

    At the end of the day accurate speed measurement is, for me, just academic. I know my cruising speed is OK because I overtake loving couples strolling along the canal bank but can get overtaken by determined looking hikers. My current focus is to rearrange the steering linkage because it gets knocked by the rod which connects the pedals to the paddlewheel. It makes an annoying clang.
    What I really want to do is to make a mark II version with any faults resolved. I should sell the current version first but don't want to be without a boat. I never realised that boat building would unearth such conundrums.:)
    What I 'm really saying, and I rejoice at this, is that I've achieved my objectives after much modification so I want to enjoy it for a while and do some longer trips. I do need to pad the seat first:(
     
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  10. alan craig
    Joined: Jul 2012
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    alan craig Senior Member

    Andrew, you have a lot of potential with that little boat as well as a home built boat that works. It looks like you are using rotary pedals, which is very difficult to match to a rotary shaft because crank centres and axle centres have to be very accurate, and, unlike a steam loco your cranks are at 180 not 90 - but that would be difficult to pedal. Would it be worth trying back and forth pedals like a toy pedal car? That would eliminate the problem of getting centre distances to match exactly. They could be "upside down" pivoting from the bottom of the boat.
     
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  11. Andrew Kirk
    Joined: Jul 2021
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    Location: Chorley UK

    Andrew Kirk Junior Member

    Actually I tried treadles with 180 degree arms on the paddlewheel. It was OK on land but the resistance in the water meant that there wasn't enough momentum in the paddlewheel to keep it rotating. My pedal system works because the arms on the paddlewheel are set at 90 degrees to each other, so one or both are always being pulled or pushed. It all rotated freely once I got the connecting rod lengths spot on by screwing rod ends in or out. There's enough flexibility in the system to account for any tiny discrepancies in centre distances etc. I was getting a notchy feel to the rotation but have eliminated that with fine adjustments. I'd love to get an accurate figure for efficiency but all I know so far is that I can go along at an acceptable speed at the same effort aerobically as walking. It's a bit more muscular, though. The treadle idea was to avoid lifting the legs and feet up and down so much but because I had to use 180 degree cranks it was never going to work, I concluded. I'll post a better picture of the drive system, soon.
     
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  12. alan craig
    Joined: Jul 2012
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    Location: s.e. england

    alan craig Senior Member

    90 degree cranks on the paddlewheel? I think I get it now - you also have separate 90 degree cranks on the pedal shaft - I thought the rods were directly connected to the pedal cranks.
     
  13. Andrew Kirk
    Joined: Jul 2021
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    Location: Chorley UK

    Andrew Kirk Junior Member

    DSCF7100.JPG DSCF7101.JPG So here are some pictures of the drive. The arms on the pedal cranks are at 90 degrees to each other, as are the ones on the paddlewheel. The long connecting rods have a tiny amount of flex in them to account for any discrepancies. Now it works I need to get some paint on it.
     

    Attached Files:

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  14. Andrew Kirk
    Joined: Jul 2021
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    Location: Chorley UK

    Andrew Kirk Junior Member

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