KN Calculation

Discussion in 'Stability' started by toy, Oct 6, 2012.

  1. toy
    Joined: Oct 2012
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    toy New Member

    Anybody can help me how to manually calculate/produce KN Values in every Displacement and in every 10 degrees heel increment needed for stability booklet.Thank you.
     
  2. Adeyele
    Joined: Jun 2012
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    Adeyele Junior Member

    Helo Toy, re u studying IIMS course?
     
  3. toy
    Joined: Oct 2012
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    toy New Member

    Hi Adeyele, planning to make stability booklet.
     
  4. chandru447

    chandru447 Previous Member

  5. Adeyele
    Joined: Jun 2012
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    Adeyele Junior Member

    Helo toy, am nt planing to make any1 but I have a exercise relating to your question.
    Its exactly as your question.
     
  6. cyro
    Joined: Sep 2012
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    cyro Junior Member

    Find GZ first.We know that relation between GZ=KN-KGsin(theta)..GZ=GMsin(theta) .But it is true for angle between 0and 5degree.7degree is maximum.For larger angle of heel,use Barne's method.
     
  7. conceptia
    Joined: Nov 2009
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    conceptia Naval Architect

    Normally we use software to calculate KN and we generate GZ curves right? How is the other way working?
     
  8. cyro
    Joined: Sep 2012
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    cyro Junior Member

    Atwood's formula.It will take 4 hr to complete one curve.
     
  9. chandru447

    chandru447 Previous Member

  10. en360
    Joined: Nov 2010
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    en360 Junior Member

    Since I use software to calculate KN, forget it
     

  11. Julien_C
    Joined: Mar 2013
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    Julien_C New Member

    You need to:
    1. Section your boat
    2. Calculate the heave a trim for a given heel angle so that the integral of immerged surface area of the sections gives you the proper volume and LCB
    3. Calculate the position of the centre of buoyancy using a barycentre calculation
    4. Use trigonometry to find KN
    Unlike someone said earlier, you don’t calculate GZ first then KN but the opposite. A stability software always calculate KN first then derives GZ. Remember that KN represent the form stability. Which means that once you have your KN curves you can derive your GZ curve for any VCG you like.

    The KN curves isolate the form stability from the mass stability.
     
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