hello,we have a problem in stepped planning craft

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

  1. Mr Efficiency
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    Mr Efficiency Senior Member

    And the boat is not leaning to one side or the other when this is happening ? What kind of drive(s) are fitted (e.g. shafts, or sterndrives) ?
     
  2. jimhongfei
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    jimhongfei Junior Member

    when the engine rotate speed is high(1800-2000rpm). we use sterndrives
     
  3. Mr Efficiency
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    Mr Efficiency Senior Member

    It is difficult to understand what is happening, I assume you have a steering system with no feedback, yet on completely flat water, at speed, it does what, pull to one side, or wander in either direction ?
     
  4. jimhongfei
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    jimhongfei Junior Member

    sorry for my poor english. the problem is put to one side in the bow
     
  5. Mr Efficiency
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    Mr Efficiency Senior Member

    Pulls to one side and working the helm does not straighten it up ? Trimming the drives out makes no difference ?
     
  6. Milehog
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    Milehog Clever Quip

    Are the rudders-drives aligned properly? You need to check the simple things first.
     
  7. Mr Efficiency
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    Mr Efficiency Senior Member

    He says boat is using sterndrives, I wonder are they counter-rotating pair ?
     
  8. jimhongfei
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    jimhongfei Junior Member

    there is no problem. when it drivers slowly (speed:0-20kn).i don't think this is the reason.
     
  9. jimhongfei
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    jimhongfei Junior Member

    but the sterndrives has no rudders-drives.
     
  10. jimhongfei
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    jimhongfei Junior Member

    "counter-rotating pair" this means?
     
  11. Mr Efficiency
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    Mr Efficiency Senior Member

    If it has counter-rotating props and/or hydraulic no-feedback steering, and won't hold a line in flat water and calm air, at a constant speed, it is too clever for me !
     
  12. Mr Efficiency
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    Mr Efficiency Senior Member

    One propellor turns clockwise, the other anti-clockwise.
     
  13. Milehog
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    Milehog Clever Quip

    Whatever is used to steer the craft have to be properly aligned in multiple engine applications.
     
  14. jimhongfei
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    jimhongfei Junior Member

    you means:the propellor turns to the same.but all of our yacht's propellor "One propellor turns clockwise, the other anti-clockwise"
     

  15. Mr Efficiency
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    Mr Efficiency Senior Member

    Gearcases are made to rotate opposite to the normal clockwise ( looking from behind the boat) and use propellors similarly opposite, this cancels out torque effects in a twin set-up.
     
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