Horizontal fin drive trimaran

Discussion in 'Multihulls' started by Eric Lundy, May 21, 2019.

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Is this fin drive feasible?

  1. Yes

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  2. Best design since the paddlewheel.

    0 vote(s)
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  3. Ideas are like A holes, everyone has one and they all stink.

    0 vote(s)
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  1. Eric Lundy
    Joined: May 2017
    Posts: 19
    Likes: 2, Points: 3
    Location: Vermont

    Eric Lundy Junior Member

    Hello, I would like to discuss the merits or problems associated with a fin type drive for a trimaran. Here is what I thought of:
    A trimaran that you rock from side to side like a pendulum. (everyone knows you can rock a monohull with a foil centerboard or keel to create forward thrust) . On each ama is an adjustable spring loaded (in the vertical axis) horizontal fin that while you rock the boat and move forward create a sinusoidal fin movement and more forward thrust. The spring is to allow the water to deflect the fin the correct amount to create maximum thrust throughout each rocking period. The spring fin stiffness adjustment is for the current speed as a different spring tension on the fin may be needed depending on speed. or a "sweet spot" could be found for maximum efficiency at the majority of speeds. Each ama is designed with enough flotation to allow for reversing the pendulum effect to counter your body weight or whatever you are using to create the pendulum effect. I was thinking that the fin itself could be flexible to allow for twist as the tip of the horizontal foil as the outside will be travelling faster vertically than the inside. Think splitting a whale tail in the middle and attaching each tail center to the tip of your ama rudders like an L to the outside.... then rock the boat! What could the theoretical efficiency of this drive be?
    Similarly the hobie mirage drive has flexible fins but only scissor and do not truly take advantage of a sinusoidal wave form. Just a flapping motion really. not as much lift.
    Yes I am building this currently as an experiment. I am no expert and not in school but would like more information from you true experts as my build develops.
    Cheers, Eric
     
  2. trip the light fandango
    Joined: Apr 2018
    Posts: 221
    Likes: 37, Points: 28
    Location: Rhyll Phillip Island Victoria Australia

    trip the light fandango Senior Member

    Hi Eric, it seems counter intuitive to create a rocking motion to a trimaran when that is one of its best assets, it doesn't rock easily so your less likely to feel seasick. How is your motion sickness thresh hold?. I'm not an expert but, every action creates an equal and.. well that's enough to google the amount of force exerted to get going will be proportional to the weight to create forward motion,and require constant feed once at cruising speed . So two people synchronised on a surfboard each like a sideways seesaw?
    It reminds me of a silent movie, Buster Keaton like. Flexible drive[more like a robotics forum?] as a series of valves such as hydraulics, or solenoids , creating contraction like muscles do couldn't be that far off, less risk of fouling, intestines, snakes, fish, there's a dance move, the Mexican wave. perhaps it would feel good, soothing? Just a thought stream, cheers.
    I couldn't vote Eric ,on the fence for this one
     
    Last edited: May 25, 2019
  3. Eric Lundy
    Joined: May 2017
    Posts: 19
    Likes: 2, Points: 3
    Location: Vermont

    Eric Lundy Junior Member

    My motion sickness threshold is immense. And the teeter totter/ seesaw reference is spot on. The pivot/ fulcrum is the central hull then each ama would be the playful children. My build begins today, a small one person craft.
     

  4. Doug Lord
    Joined: May 2009
    Posts: 16,478
    Likes: 287, Points: 93, Legacy Rep: 1362
    Location: Melbourne, Florida

    Doug Lord Flight Ready

    I think it will work -good luck!
     
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