Why aren't offshore tunnel hulls using forward wings to control bow lift?

Discussion in 'Boat Design' started by FranklinRatliff, Mar 28, 2012.

  1. FranklinRatliff

    FranklinRatliff Previous Member

    Moving forward wings work on Unlimited hydroplanes. Why not the big tunnel hull boats?
     
  2. Mr Efficiency
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    Mr Efficiency Senior Member

    My guess would be pitching amplitudes of offshore boats are such that wings would be ineffective in giving a controlled amount of lift/downforce, if just fixed in place. And having them automatically constantly adjusting to pitching angles seems a touch problematical.
     
  3. mydauphin
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    mydauphin Senior Member

    The hull is already designed to provide downforce. If it lifts the wing on top will stall out anyway because of the airfoil of hull blocking it. Wings add downforce but they also produce drag.
     
  4. FranklinRatliff

    FranklinRatliff Previous Member

    Doesn't seem to slow down Unlimited hydroplanes.

    The drivers use a foot pedal to control the wing so they either fly the boat or drop the bow if it's about to blow over.
     
  5. FranklinRatliff

    FranklinRatliff Previous Member

    The hull is designed to provide LIFT, not downforce.
     
  6. Mr Efficiency
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    Mr Efficiency Senior Member

    The pedal controlled wing could produce some shattering re-entries offshore if over-applied, IMO.
     
  7. mydauphin
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    mydauphin Senior Member

    The bottom part provides lift, the top is designed to provide some downforce and stability.
     
  8. FranklinRatliff

    FranklinRatliff Previous Member

    So? Hydroplane drivers face the same conditions and they're in the front of the boat, not the back.
     
  9. Mr Efficiency
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    Mr Efficiency Senior Member

    The difference is in the waves encountered offshore.
     
  10. FranklinRatliff

    FranklinRatliff Previous Member

    Offshore hulls are built to take their bows slamming into waves. What they're not built for is blowing over.
     
  11. PAR
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    PAR Yacht Designer/Builder

    The wings used on three points work in a different way, as pointed out, but another consideration is the concentration necessary to use them. It's one thing to ask it be adjusted manually in a relatively short, near shore race. It's entirely a different matter to ask it be continuously employed offshore, where the races and sea state conditions range considerably. Now, it would be possible to hand over control to a computer and some sensors, though I wouldn't want to be the programer.
     
    Jimboat likes this.
  12. FranklinRatliff

    FranklinRatliff Previous Member

    Give me a break. An Unlimited hydroplane has a crew of ONE who has to do EVERYTHING. An offshore tunnel hull typically has a crew of two to three.
     
  13. BMcF
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    BMcF Senior Member

    That is pretty much how it was explained to me by a friend of mine who has raced both types for decades. In his hydro, the front wing is coupled to his steering yoke (it slides in and out) and skill managing that wing is important to keep the angle of attack of what is essentially a boat flying in surface effect very constant.

    Ofshore racing hulls are more dominated by hydrodynamic planing forces and the pitching of those hulls would be little affected by twiddling a small trim wing.
     
  14. FranklinRatliff

    FranklinRatliff Previous Member

    Unlimited hydroplane drivers use a foot pedal to control the front wing.

    http://farm2.staticflickr.com/1210/902227350_decd8d3f63_z.jpg

    And WTF said I was talking about a "small trim wing"?

    http://www.youtube.com/watch?v=9YPAxuoPpXo

    And guess what? Most of the boat is not even touching the water. NOT dominated by hydrodynamic forces.
     

  15. gonzo
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    gonzo Senior Member

    There is no need for "WTF" or other of your comments. Please be polite.
     
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