Small electric cat - hydrofoil

Discussion in 'Boat Design' started by Eciton, Sep 23, 2018.

  1. Eciton
    Joined: May 2017
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    Location: Virginia

    Eciton Junior Member

    was watching youtube and seeing a lot of small jetboards using electric motors to push a surfboard to the speed required to "fly" using a hydrofoil system. I was tossing the idea around of something a little larger, perhaps a 12' cat with folding foils that can fold up into the space between the hulls.

    seems there are a number of sailing cats with foils, and human powered cats with foils - so the speed cannot be so much that a modern electric motor and batt system couldnt do the same.

    question: as I am not an engineer, just a tinkerer. ideally I would want no more than 2 wings under the boat and ideally the ability to swing them up between the hulls to beach or trailer.

    1.) how do you size a hydrofoil element? I assume its a combo of power available, surface area of the wing, wing design, and boat size but I'm not clear on the details

    DISCLAIMER: I have not done any research on the design other than a quick google to see that I have not seen a similar creature out there.
  2. Doug Lord
    Joined: May 2009
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    Location: Melbourne, Florida

    Doug Lord Flight Ready

    This may help you to think it out: Lift Foils - Home of the eFoil electric hydrofoil surfboard, now shipping
    Note-price is $12,000!
    You could use a strut system like the efoil-perhaps a bit larger to reflect greater weight- and have the whole assembly retract between the hulls using a trunk in the crossarm structure.
    If you are really interested get "Design Build Fly" by Ray Vellinga which is, in essence, a design/build manual for small hydrofoil boats.

  3. Eciton
    Joined: May 2017
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    Location: Virginia

    Eciton Junior Member

    yes, that is the youtube video I saw that got my brain working on this idea to begin with.

    $12K is loco, there is a good amount of info on their site though thanks for the link.

    anyone else thats interested, theres a fairly active DIY efoil site

    Electric Hydrofoil Builders

    seems like the biggest issue is getting a motor strong enough with a battery system light enough.
  4. vinotinto
    Joined: Jun 2017
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    Location: Earth

    vinotinto New Member

    Search for solar boat challenge, few teams have competed with a foiling cat, most successful boats have been a trimaran design. these boats are of course optimized around rules and fairly sheltered dutch canals, interesting design features nonetheless..
  5. Eciton
    Joined: May 2017
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    Location: Virginia

    Eciton Junior Member

  6. portacruise
    Joined: Jun 2009
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    Location: USA

    portacruise Senior Member

    These really look cool, but curious about what the limitations are with foils? How long does it take to master the skills to use the surfboard type? What is the maximum allowed for wave heights, draft, and weed plus debris issues for being able to use them? Seems like the cat design might be a little more versatile, especially if the foils can be designed to be pulled up high enough to clear the water. The cat design might used at slow speeds under unfavorable conditions as a backup or limp home mode.
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