Boat Design Software with Good Stability Analysis

Discussion in 'Software' started by waynep, Sep 30, 2010.

  1. Martijn_vE
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    Martijn_vE Marine software developer

    No, it's not (at least up to version 2.6) which makes it next to useless especially for small boats.
     
  2. smp
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    smp Junior Member

  3. J Feenstra
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    J Feenstra Junior Member

    Don't you need the Orca plug in for extracting the GHS markers?
     
  4. smp
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    smp Junior Member

    MAAT Hydro just operates directly on Rhino's IGES exports and doesn't need any plugin. It provides free real-time hydrostatic analysis, basic stability calculations, etc...
     
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  5. quequen
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    quequen Senior Member

  6. terrnz
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    terrnz Junior Member

    I have a problem with FreeShip stability calculation of soft curves in that although there is a an input field for center of gravity (VCG) it seems to have no effect on the cross curve values. I am working with yacht designs and clearly a deep keel and bulb ( resulting in a negative VCG) should have a significant effect on righting moment.
    The KNsin data is equivalent to GZ ?
    Is the KNsin data only form stability ?
     
  7. jonathan
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    jonathan Junior Member

    KNsin(Ф) is only form stability, yes, but it is fairly easy to compute the actual GZ from it. Just add or substract the horizontal distance from the center of gravity to the keel, and that will get you the GZ.

    The actual formula would be GZ = KN*sin(Ф) - KG*sin(Ф)

    If your center of gravity is not on the centerline, do not forget to take it into account.

    Hope that helps.
     
  8. terrnz
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    terrnz Junior Member

    stability

    Ok formula which have the I have worked with. My question is: taking the measurements from the lowest point of the hull as base line which is how FreeShip and Delft work with a light displacement sailboat and a bulb keel you have a negative CG . it makes sense to me mathematically and empirically and seems to give a credible figure.
    Should VCG be taken from the base line or VCB?
    changing the baseline to the lowest point of the keel/bulb so all figures are positive gives an unrealistic value. I am probably doing something wrong:confused:
     
  9. terrnz
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    terrnz Junior Member


    what do you define as a small boat LOA?
     

  10. TANSL
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    TANSL Senior Member

    Of course.
    Choose a baseline, whatever you want, and take all measures regarding that B.L.
    Before you start calculating things, it would be convenient to review your concepts about ship theory. Ask your questions here, as simple as they may seem, and we'll give you some answers, but you must provide some basic knowledge.
     
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