Cross Curves of Stability (KN-Values)

DELFTship forum Hydrostatics and stability Cross Curves of Stability (KN-Values)

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    • #43911
      martin_
      Participant

      Dear Community,

      Which method is used in the software to get the KN-Values, which are normally tabulated in the stability booklet of a pontoon/vessel?

       

      Regards,

      Martin

       

       

    • #43927
      Marven
      Keymaster

      Martin,

      The program calculates the longitudinal center of buoyancy for the selected displacement and trim in the upright condition and places LCG above LCB.
      Then for each list angle the sinkage and trim is calculated where the (heeled) trim is obtained by balancing the hull until LCG is again above LCB.
      Finally the KN value is the horizontal distance between the keel and the center of buoyancy.
      An image showing these values can also be found in the manual.

    • #43970
      martin_
      Participant

      Dear Marven,

      Would you tell me where I can find more about this method, as it is still not feasible to me?

      Comparing the KN and GZ Values of a given Pontoon’s stablity booklet with the results obtained by theĀ  software for the same pontoon I see different figures.

      All I can find about large angles is the Wall-Side Formulae, which is not valid anymore once the deck is in the water.

       

      Brgds,

      Martin

       

    • #43971
      Maarten
      Keymaster

      Hi Martin,

      What version (ModuleCode) of DELFTship are you using? KN and GZ values are not available in the Free or the simple Professional version- you will need at least the Inclined hydrostatics extension.

    • #43973
      martin_
      Participant

      Hi Maarten,

      I am not sure about the version. I was only provided a print-out report to verify the calculations for a client. Then I came across with the KN-Values and GZ-Curve and was wondering about the method you apply.

       

      Is it possible to purchase only the extension module for determining tabulated KN-Values?

      • #43974
        Marven
        Keymaster

        Hi Martin,

        Sure, you would need DELFTship professional and the cross curves extensions for that. I’ll send you the pricelist by PM.

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