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Thread: Why aren't true hydrofoils (not the anti-ventication plate add-ons) common on boats?

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    Member Maast's Avatar
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    Default Why aren't true hydrofoils (not the anti-ventication plate add-ons) common on boats?

    Read a magazine article recently (Popular Mechanics I think) and they were going on about the virtues of a hydrofoil boat: faster, 40-50% better fuel economy, smoother ride in chop and waves, etc. They made a really convincing case.

    I'm talking about a true hydrofoil with a NACA-type airfoil shape that provides maximum lift vs drag - NOT those outboard anti-ventilation plate add-ons.

    I'm thinking I'd like to have a partial hydrofoil under the new boat to at least lift me up out of the water a good bit and reduce my wetted area/drag.

    Maybe mounted a few feet forward of the transom on a swing arm with a shear pin holding down a pivot that'll allow the foil to swing rearward and out of the water if I hit something.

    I did a little google research and there's nothing really out there for power boats, trim tabs will lift up the back end of a boat pretty well, but the lift/drag ratios stink. I did find a company that had some surplus extruded aluminum airfoils - but they were only about 4 inches wide.

    Thoughts?
    Last edited by Maast; 12-30-2009 at 11:21. Reason: Dang - can't edit titles for spelling.
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    Member Sobie2's Avatar
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    Doel Fin is a true hydro foil. I have them on all my boats and have bought them for my buddies' boats.

    But you want to make a regular boat a real full flying hydrofoil, and that would make all of popular mechanics claims true.

    Sobie2

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    Member Vince's Avatar
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    Quote Originally Posted by Maast View Post
    Read a magazine article recently (Popular Mechanics I think) and they were going on about the virtues of a hydrofoil boat: faster, 40-50% better fuel economy, smoother ride in chop and waves, etc. They made a really convincing case.

    I'm talking about a true hydrofoil with a NACA-type airfoil shape that provides maximum lift vs drag - NOT those outboard anti-ventilation plate add-ons.

    I'm thinking I'd like to have a partial hydrofoil under the new boat to at least lift me up out of the water a good bit and reduce my wetted area/drag.

    Maybe mounted a few feet forward of the transom on a swing arm with a shear pin holding down a pivot that'll allow the foil to swing rearward and out of the water if I hit something.

    I did a little google research and there's nothing really out there for power boats, trim tabs will lift up the back end of a boat pretty well, but the lift/drag ratios stink. I did find a company that had some surplus extruded aluminum airfoils - but they were only about 4 inches wide.

    Thoughts?
    i had this discussion with a group of engineers a few years back... great thoughts and concepts.. one word...


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  4. #4

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    A guy that I freedive with, has a hydrofoil assisted aluminum cat. I haven't been on the boat or seen it in person yet, but it has some type of foil between the sponsons that lifts the boat an additional 5-6 inches, while on plane, to reduce the wetted surface. It is supposed to make it quite a bit more fuel efficient and he claims it makes 50kts. That is quite a bit faster than I would expect a boat of that size to make with dual 225.


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    Member AK NIMROD's Avatar
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    Stolkraft hull deisn gives lift similar to hyrdo foil very stable and fast
    many years ago rode from Manila to Corrigador in a true hydrofoil WOW what a ride, BUT the
    pretty "deck hand / tour guide" had very nasty scar across her face. The hydrofoil "wing " hit shark at high rate of speed, came off step rapidly and she was thrown foreward and injured.

    wish some one was making aluminum Stolkraft design in US ( under 40 foot) they would make a great boat....if i could afford one??? Armstrong power cats would be good second choice, saw some of those in Sitka last summer. Can't afford those either.
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    Member FISHFACE's Avatar
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    wish some one was making aluminum Stolkraft design in US ( under 40 foot) they would make a great boat....if i could afford one??? Armstrong power cats would be good second choice, saw some of those in Sitka last summer. Can't afford those either.[/QUOTE]



    this is what our Armstrong 30'x11' looks like at 30 knots. not quite as much lift, but it does get out of the water.
    Attached Images Attached Images

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    I've been on one of these and its derivatives many times back in Russia, I think they still have them.
    From what I could find it has a 2400 hp engine (jet?) and does 32 knots.
    All I remember as a kid is that it was way fast and very noisy.

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    Member russiarulez's Avatar
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    My uncle used to have one of these (couldn't find a better pic). I remember him saying that debris in the water was always a problem, especially larger logs that would just shear the hydrofoil off.



    And here's a larger version:


  10. #10

    Default I've always wondered about...

    ...retractable hydrofoils for the floats on floatplanes...

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