What to converge on Damage Stability?

Discussion in 'Stability' started by mactavish, May 22, 2022.

  1. mactavish
    Joined: Sep 2014
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    Location: philippines

    mactavish Junior Member

    Hi Mates,

    I have a question regarding the damage stability.

    I know there are two methods:
    - Loss of buoyancy method
    - Added weight method

    My question is. What do we have to converge on the calculation in order to get the Damage stability right?

    Is the iteration to converge the CoG and CoB until they are aligned to each other both for trans and longi positions? is that where you stop the calculations iteration?
     
  2. jehardiman
    Joined: Aug 2004
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    Location: Port Orchard, Washington, USA

    jehardiman Senior Member

    When conducting a calculation for damaged stability, whether inside out (lost buoyancy) or outside in (added weight), there are additional criteria besides necessary rigid body physics.
    1) There is a minimum GM at all stages of flood-up including free surface (c.f. the MV ROCKNES capsize).
    2) There is a minimum area under the righting curve for all stages of flood-up. (c.f. MV TRICOLOR)
    3) Conservative calculation in either the ever-buoyant volume or the Permeability
     
  3. TANSL
    Joined: Sep 2011
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    TANSL Senior Member

    By calculating the intact stability at any loading condition you calculate the equilibrium floatation, for which you also need to compromise on the exact positions of both points. Use the same accuracy in damage stability calculations.
     
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  4. jehardiman
    Joined: Aug 2004
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    Location: Port Orchard, Washington, USA

    jehardiman Senior Member

    Yes, the whole idea of Center of Permeability is fraught with issues.
     
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