Gunboat G4 with UptiP Foils

Discussion in 'Multihulls' started by Doug Lord, May 12, 2014.

  1. brian eiland
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    brian eiland Senior Member

    Now who wouldn't want to take a sail on that thing WOW :!: ...good find Doug

    Am I seeing only a few battens in that mainsail,....up top only??
     
  2. Doug Lord
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    Doug Lord Flight Ready

    G4 cruiser/racer on foils!

    Yeah, I think so. You know it has to have a diagonal batten at the head but I can't see it-so maybe others are invisible?
     
  3. Corley
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    Corley epoxy coated

    I'm thinking that a lot of people will also order the G4 with the curved foils rather than the uptip version for foil assist, perhaps not as spectacular or as fast but still fun. I gather the case structure would be the same in either option? If you had both that would give the option of occasionally fitting the full lifting foils for a race.
     
  4. Doug Lord
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    Doug Lord Flight Ready

    G4 cruiser/racer on foils!

    I don't see the point in buying two sets of foils when you can so simply detune the UptiP foils: put both half down and set the AOI for zero degrees....
     
  5. Corley
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    Corley epoxy coated

    Doug, I can see all sorts of good practical reasons for wanting curved foils in a boat that is kept in the water, being able to withdraw them up above the waterline for instance. The website doesn't say but I gather the G4 can dry out on it's own bottom that alone is worth being able to withdraw foils or can it sit on the lifting foil surface ok? On the G4 page it notes that the rudder is retractable too.
     
  6. brian eiland
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    brian eiland Senior Member

  7. daiquiri
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    daiquiri Engineering and Design

    Now that's a way to go really fast. :)
    Though those active controls appear to work too frantically and hence create too much induced drag on the foils. A more intelligent flight control mechanism is needed, imo.
     
  8. Doug Lord
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    Doug Lord Flight Ready

    Seemed about as "frantic" as any mechanical wand system.....
     
  9. daiquiri
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    Location: Italy (Garda Lake) and Croatia (Istria)

    daiquiri Engineering and Design

    Yes. I was not comparing it to other wand systems, I was talking in absolute terms. The foils of that video imo move too much and with too high frequency. An averaging mechanism (damper or shock absorber) placed at the mechanical link between the wand and the foil would reduce the added resistance caused by such frenzy motion.
     
  10. Doug Lord
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    Doug Lord Flight Ready

    wands

    Check out these Moth wands: (Keep in mind this is the fastest sailboat under 20'--35.9knots/41.3mph) It would be a project requiring lots of practice but I've always been convinced that if you connected the tiller twist grip to the flap on the main foil, you could manually fly the boat ,eliminating the high frequency flap movement.
    https://www.youtube.com/watch?v=RABxXlwRfAc#t=21
     
  11. brian eiland
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    brian eiland Senior Member

  12. tspeer
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    tspeer Senior Member

    Look for a copy of David Keiper's book, "Hydrofoil Voyager". It's a combination autobiography and description of the boat.

    AFAIK, Williwaw is still the only hydrofoil of any kind (including the military hydrofoils), capable of full foilborne operation, that has crossed an ocean.

    It was a 31 ft plywood trimaran with aluminum foils. IIRC the aluminum extrusions were originally intended for helicopter blades. Unfortunately, the boat was destroyed in 1977, when her anchor drug in a storm and she was driven onto shore, capsized, and pulverized.
     
  13. DCockey
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    DCockey Senior Member

    Agree about the foil movement and need for damping. I wonder if there is a bit of resonance occurring in that system. If so damping would minimize or eliminate it.
     
  14. P Flados
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    P Flados Senior Member

    Keiper was

    • As much of more of a foil nut than Doug ;)
    • A man with a "vision" who saw how foils were worth the effort
    • A gifted "doer" that put ideas into action
     

  15. catsketcher
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    catsketcher Senior Member

    Dave Keiper would be happy today. I interviewed him for an Australian magazine in the mid to late 90s. He was still designing foilers and sent me a computer drawing of a foiler with ladder foils off each side - a rudder foil and a bow foil that we featured in the magazine. When I asked him about the future he said that foilers were going to be big news in the future. It took a while but he seems to be right nowadays.

    cheers

    Phil
     
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