hello,we have a problem in stepped planning craft

Discussion in 'Boat Design' started by jimhongfei, Jun 2, 2013.

  1. jimhongfei
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    jimhongfei Junior Member

    hello,everyone
    our company has builded a stepped planning craft,it's a 38ft yacht.there is a problem. if it's sailing in Speed to full .it will lead to course instability .
    thanks for you replying.
     
  2. jimhongfei
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    jimhongfei Junior Member

    I'm waiting for you reply online
     
  3. Mr Efficiency
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    Mr Efficiency Senior Member

    Pictures or drawings would be helpful for people forming opinions about why it is lacking directional stability at speed.
     
  4. Milehog
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    Milehog Clever Quip

    I am sorry for not getting back to you sooner.
    The boat was poorly designed and built. Hope this helps.
     
  5. JSL
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    JSL Senior Member

    drawings or photos would help us understand the hull form. Check with your designer to see if he can fix the problem. My guess... sounds like chine walking or chine running: the boat comes up on the plane and then wants to heel over to port or starboard. In some cases you get 'bow steering' which is like driving a car on ice. Quite scary.
    I have been involved with a few cases (not my designs, thank goodness) and the cure can sometime easy or very elusive... if there is one at all. In 2 cases, the boats were incurable and abandoned. Quite expen$ive.
     
  6. jimhongfei
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    jimhongfei Junior Member

    thank you very much

    i have upload some pictures.
     

    Attached Files:

  7. Mr Efficiency
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    Mr Efficiency Senior Member

    What is the weight of the boat ? Seems like it might be pretty heavy if it sits on the waterlines painted on it. Any other pictures ?
     
  8. jimhongfei
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    jimhongfei Junior Member

    thank you very much

    i have upload some pictures. do you havetime to see it thankyou
     
  9. jimhongfei
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    jimhongfei Junior Member

    i'm sorry i have no pictures anymore.weight of the boat is 4.59t.

    i'm sorry i have no pictures anymore.weight of the boat is 4.59t.
     
  10. jimhongfei
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    jimhongfei Junior Member

    you are right ,but we need to solve the problem.can you help me

    you are right ,but we need to solve the problem.can you help me
     
  11. Mr Efficiency
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    Mr Efficiency Senior Member

    So when does it show the tendency to go "off course" ? In flat water, or only in certain angles to waves ?
     
  12. jimhongfei
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    jimhongfei Junior Member

    thank you very much

    i think you are a very excellent designer. and i think i have the problem like you's. when the heel sail "heel over to port or starboard". how did you do in your case? i don't want my boat to be a bad design.
     
  13. jimhongfei
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    jimhongfei Junior Member

    in flat water
     
  14. Mr Efficiency
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    Mr Efficiency Senior Member

    At what speed does it have the problem ?
     

  15. jimhongfei
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    jimhongfei Junior Member

    design speed :30kn
    we have the problem in 20-30kn
     
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