KnifeFoil

Discussion in 'Boat Design' started by David J Ritchie, May 21, 2018.

  1. David J Ritchie
    Joined: Jan 2018
    Posts: 19
    Likes: 1, Points: 3
    Location: Victoria BC Canada

    David J Ritchie Junior Member

    Me:
    First off I am your average ordinary kooky inventor. Currently I am working mainly on exotic green energy technologies. I have had a passion for vehicles for most of my life. I am not a engineer nor do i have that skill set so please teach me kindly.


    Originality:
    I went through 400+ hydrofoil designs and so far I have not found its twin. Let me know if you think this was designed before as I would love to give credit to the original designer. As far as I know this is all mine.


    Inspiration:
    I was watching small light and fast planning tunnel hulls. I hate the efficiency of the planning hull. So the idea was to replace the planning lift of the tunnel hull with fixed hydrofoils.


    So what is it:
    It amounts to a jon boat but with two oversized skegs coming down the entire length of the beam, this is essential for trapping tunnel forces in. Coming off the inside of the skegs, in canard formation, are 2 sets of fixed hydrofoils, these replace planning lift. The rear set of hydrofoils are canted downward and the front set have an upward angle of incidence, for automatic stability. Ordinary but oversized trim tabs pushing on compressed air instead of water, for keeping righting moment. Altho not included in my primitive drawings the power and steering are accomplished by an ordinary outboard motor, extra long shaft with wave piercing prop. I call it the Knifefoil as it will slice its way so well through the water.


    Advantages:
    -Less water resistance than any planning hull will produce more speed with the same power
    -More vertical stability than any other powered fixed hydrofoil
    -Wider tunnel = more tunnel lift than any other tunnel hull


    Disadvantages:
    -Terrible draft wile at rest or going slow
    -High CG wile up on foil
    -Engineering and tuning will present a serious challenge


    Keys to Success:
    -Tunnel compression and decompression will cause automatic vertical stability by counteracting the hydrofoils tendency to lift up to the waters surface turbulence stall and crash down

    -Downward canted main hydrofoils so as port or starboard side lowers it gets more lift and if it raises it will get less lift for automatic righting moment

    -Upward angle of incidence of 10 deg or less on the canard so as the bow rises it looses lift and when the bow falls it gains lift imparting automatic bow stability

    -Load bearing canards will be tuned to stall long before the main foils will, this will drop the bow making the Knifefoil fall forward causing more forward momentum and lowering the canards into more laminar water flow both creating more canard lift creating automatic stability

    -All automatic stability described above will need serious tuning to ensure the reactions induced by instability are exactly proportional and faster than human perception

    -Like all tunnel hulls the bow will sit higher and the stern will sit lower squeezing the trapped air down onto the water and compressing it, the hydrofoils will need to be calibrated to achieve this stance

    -Beam skegs need to be as thin as possible yet robust enough to bear the total weight load

    -Oversized trim tabs for compressed tunnel air once up on foil hopefully controlled by skipper or may need gyro-computer control

    -Intended to avoid cavitation by under 50 knots cruse
     

    Attached Files:

    Last edited: May 23, 2018
  2. David J Ritchie
    Joined: Jan 2018
    Posts: 19
    Likes: 1, Points: 3
    Location: Victoria BC Canada

    David J Ritchie Junior Member

    I would like to build a dingy size version of my KnifeFoil can anyone tell me why they think it won't work? If it will work, I'm looking for a brave sole willing to engineer this bad boy? I will build to your specs and give feed back,
    we can discuss tuning step by step all online, i will build and rebuild. I was thinking simple construction maybe just S&G. For the foils i was thinking we could maybe cheat by cutting 2 planning fins in two and heavy glassing them on, all hand laid.
     
  3. David J Ritchie
    Joined: Jan 2018
    Posts: 19
    Likes: 1, Points: 3
    Location: Victoria BC Canada

    David J Ritchie Junior Member


  4. David J Ritchie
    Joined: Jan 2018
    Posts: 19
    Likes: 1, Points: 3
    Location: Victoria BC Canada

    David J Ritchie Junior Member

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