Stabilisers

Discussion in 'Boat Design' started by Saqa, Jun 11, 2021.

  1. Saqa
    Joined: Oct 2013
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    Saqa Senior Member

    In the very near future, I will start work on a pedal boat project, and currently I am thinking up ways to cross water very fast in a stabilised mono hull

    I saw people referring to stabilisers as training wheels, which got me thinking. What are the pros and cons of using actual wheels? A rubber tube on a plastic rim will be nice and light and turn with water contact. Would this negate skin friction? Is this a stupid idea?
     
  2. Saqa
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    Saqa Senior Member

    One interesting thing about the pedal boat is that I am making a drive system that works like a bulldozer belt. I believe I have solved the hassles and ready to make a prototype
     
  3. dreamingbarrierreef
    Joined: Oct 2018
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    dreamingbarrierreef dreamingbarreef

    I (still) remember a thread about a heroic French guy rolling across the Atlantic in a wine barrel. Which got me thinking at the time whether rolling motion was probably lot more efficient to cross sea. And this was the searover in mind. (If it flips over, the wheels flip to the other side. But obviously require huge hydraulics. And the sphere is gimbaled.) One way to make use of skin friction & rolling motion. No mouses running in the wheels, so no animal abuse there. But probably something along the concept.

    searover.png
     
  4. Robert Biegler
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    Robert Biegler Junior Member

    I remember reading an article on 19th century experiments with exactly this idea. It has two problems:
    1) To get a halfway decent shape, you need to keep draft small relative to the radius of the wheel, which means a very large wheel with more reserve volume than you are likely to need. That gives you a larger weight and more windage than a hull that would do the same job.
    2) Water sticks to the rotating wheel, and is lifted up at the aft end. That takes energy.
    An experiment with relatively deeply immersed wheels (for an amphibious land yacht) found they were being sucked down at speed. The shape needed to be modified to make short planing hulls. See Caltalyst #32 at Catalysts – Amateur Yacht Research Society https://www.ayrs.org/catalysts/

    If you go fast enough, you can stabilise the boat the same way you stabilise a bicycle, by steering into a turn. There are at least two pedal-powered watercraft designed to do that, one of them without even a hull, relying on foils only. Mount outrigger hulls high enough that they don't touch the water in normal operation, but only when you go too slow to stabilise by steering.
     
    dreamingbarrierreef likes this.
  5. ondarvr
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    ondarvr Senior Member

    There is a long thread on this site about this subject, it was a while back.
     
  6. portacruise
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    portacruise Senior Member

    UniversityDisplacementHPBs http://www.humanpoweredboats.com/Photos/UniversityDisplacementHPBs/UniversityDisplacementHPBs.htm

    Lots of ideas on this link. Check out the Tuhhsnelda near the bottom of the university pictures page.

    The need for streamlining can be discarded in some designs when skin friction is used as a positive force for propulsion, rather than being a dragging negative Force which must be minimized.
     
    Last edited: Jun 12, 2021

  7. Saqa
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    Saqa Senior Member

    Dreamin, that's a beautiful out-of-the-box concept. More future fun projects :) It does make a kind of sense

    Robert, thanks for the information. It really was an education. I will be using the pedal craft on the beach, so everything has to bash through some waves at times. I am also chasing a cruise speed higher than kayaks and pedal hobbies and similar as a show off thing

    Thanks for sharing the info man
     
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