Stability Citeria related to ship size

Discussion in 'Stability' started by Ventura, Oct 18, 2023.

  1. Ventura
    Joined: Oct 2023
    Posts: 1
    Likes: 0, Points: 1
    Location: Malasia

    Ventura New Member

    I wonder why IMO stability critera of smaller vessels and larger vessels are the same, that they depend on value of GZ , not to address the displacement i.e.
    1. The area under the righting lever curve (GZ curve) should not be less than 0.055 metre-radians up to 30° angle of heel.

    2. The area under the righting lever curve (GZ curve) should not be less than 0.09 metreradians up to 40° angle of heel or the angle of downflooding if this is less than 40°.

    3. The area under the righting curve between the angles of heel of 30° and 40° or between 30° and the angle of downflooding if this angle is less than 40°, should not be less than 0.03 metre-radians.

    4. The righting lever GZ should be at least 0.20 m at an angle of heel equal to or greater than 30°.

    5. The maximum righting arm should occur at an angle of heel preferably exceeding 30° but not less than 25°.

    6. The initial metacentric height GMo should not be less than 0.15 m.

    7. Severe wind and rolling criterion (weather criterion)

    Does that mean the smaller vessel and larger vessel, having equal value of GZ, would have the same qualification realted to stability ?
     
  2. jehardiman
    Joined: Aug 2004
    Posts: 3,729
    Likes: 1,120, Points: 113, Legacy Rep: 2040
    Location: Port Orchard, Washington, USA

    jehardiman Senior Member

    Size doesn't matter as actual righting moment scales with displacement. So a 10 ton vessel has the same proportional righting moment/energy as a 100,000 ton vessel if they both have the same GZ/area under the GZ curve.
     
    bajansailor likes this.
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