A pedal powered catamaran with sail assistance

Discussion in 'Boat Design' started by Andrew Kirk, Mar 10, 2023.

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

    Andrew Kirk Pedal boater.

    This is my second build. My first pedal powered dinghy worked well but my desires changed. I now want to be able to harness the wind on lakes as well as the power of my legs. Most of my sailing is likely to be on the nearby canal where pedal power is sufficient to cover perhaps 10 miles. I'm used to working with metal and am confident that I can bring the whole thing together at a weight of around 50 kg. I'll update this thread during the build, which may take me another 6 weeks before launch. I'll be using a pedal activated oar system which I've seen used successfully by a couple of other builders. It may not be to everyone's taste but I'm confident that I can meet my own aims. Click below for the full story so far.
    Building my new boat. https://mountainbiker.online/2023/03/10/building-my-new-boat/
     
  2. bajansailor
    Joined: Oct 2007
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    bajansailor Marine Surveyor

    I just read the story in your link.
    Can you post any copies of sketches done so far showing your proposed arrangement, and how the hulls will be joined, and the sail plan?
    You mention that the hulls will provide about 360 kg of buoyancy - at what draft will this be? And how deep are the hulls?

    Re your pedal activated oar system, will it be similar to Ben Kilner's (as per the video below) or a totally different approach?
     
  3. Andrew Kirk
    Joined: Jul 2021
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    Location: Chorley UK

    Andrew Kirk Pedal boater.

    Pride and dignity prevent me from sharing my plans/sketches! (They're very rough). I'll show some photos once I've done more on the steel parts. Brief details of my dimensions are as follows.
    Length 2.34 m. This is also the length at the waterline.
    Beam 1.20 m.
    The hulls are 0.3 m wide and 0.3 m deep, so square in cross section.
    Draft will be 12 cm with me on board.
    The central 1.6 m of each hull has parallel sides with a taper to the bow and stern of 37 cm.
    The pedal system is similar to Ben Kilner's but with the pedal shafts directly mounted to the paddles. The paddles will have telescopic shafts which I've seen used in another design.
    Steering will be by rudder. I'll build in mounts for lee boards.
    The sail will be developed later. I'm thinking of a crab claw with the centre of effort exactly half way along the hull.
     
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  4. mc_rash
    Joined: Aug 2020
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    Location: Netherlands

    mc_rash Senior Member

    I assume the 360 kg derive from totally immersed hulls, floating at deck level. With 12 cm draft it displaces around 140 kg.

    Copies/images of the arrangement would be nice! I am courious what it is supposed to look like.
     
  5. Andrew Kirk
    Joined: Jul 2021
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    Location: Chorley UK

    Andrew Kirk Pedal boater.

    Yes 12 cm draft will account for a 50 kg mass plus my own 85 kg. 360 litres is the hull volume so completely submerged they will displace 360 kg of water.
     
  6. clmanges
    Joined: Jul 2008
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    clmanges Senior Member

    Too bad you couldn't fair the lines on the hulls. Those sharp bends will create turbulence, but I don't know what kind of performance you're hoping to get, so it may not matter.
     
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  7. Andrew Kirk
    Joined: Jul 2021
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    Location: Chorley UK

    Andrew Kirk Pedal boater.

    I've managed to do a bit more work on the frames which will link the 4 hull sections together. Here is one resting on 2 hull sections and leaving the beam at 120 cm with a length of 117 cm, so the total length will be 234 cm. One frame will be boarded with ply for a recumbent seating area. The other will contain the pedal drive system and mast step. 20230313_160223.jpg 20230313_160431.jpg
     
  8. Andrew Kirk
    Joined: Jul 2021
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    Location: Chorley UK

    Andrew Kirk Pedal boater.

    It isn't a great photo but this is my half built pedal mechanism. The pedals so far are 12 mm rods which are each attached to the lower sections of 2 telescopic arms via bushes. The paddles will then be attached to the bottom of these to push the boat along. I've made it adjustable so a stroke length can be chosen. 20230322_115154.jpg
     
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  9. portacruise
    Joined: Jun 2009
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    Location: USA

    portacruise Senior Member

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

    Andrew Kirk Pedal boater.

    Yes. The mechanism works in the same way. I've made mine taller to keep the paddles more upright, entering the water around 30 degrees from vertical. There will inevitably be inefficiencies but leg power should overcome them to give me maximum hull speed capabilities. The aim is to cruise at 75% hull speed with a typical cyclists input of 150-200 watts.
     
  11. BlueBell
    Joined: May 2017
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    BlueBell . . . _ _ _ . . . _ _ _

    For what duration, may I ask?
     
  12. Andrew Kirk
    Joined: Jul 2021
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    Location: Chorley UK

    Andrew Kirk Pedal boater.

    150 watts is easy enough for one hour.
     
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  13. Andrew Kirk
    Joined: Jul 2021
    Posts: 97
    Likes: 68, Points: 18
    Location: Chorley UK

    Andrew Kirk Pedal boater.

  14. Andrew Kirk
    Joined: Jul 2021
    Posts: 97
    Likes: 68, Points: 18
    Location: Chorley UK

    Andrew Kirk Pedal boater.

    portacruise and Heimfried like this.

  15. Andrew Kirk
    Joined: Jul 2021
    Posts: 97
    Likes: 68, Points: 18
    Location: Chorley UK

    Andrew Kirk Pedal boater.

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