Regulation 27 - Intact stability
Clasification Society 2024 - Version 9.40

Regulation 27 - Intact stability

 SEE INTERPRETATION 52

  1 Every oil tanker of 5,000 tonnes deadweight and above delivered on or after 1 February 2002, as defined in regulation 1.28.7, shall comply with the intact stability criteria specified in paragraphs 1.1 and 1.2 of this regulation, as appropriate, for any operating draught under the worst possible conditions of cargo and ballast loading, consistent with good operational practice, including intermediate stages of liquid transfer operations. Under all conditions the ballast tanks shall be assumed slack.

  • .1 In port, the initial metacentric height GMo, corrected for the free surface measured at 0° heel, shall be not less than 0.15 m;

  • .2 At sea, the following criteria shall be applicable:

    • .1 the area under the righting lever curve (GZ curve) shall be not less than 0.055 m.rad up to θ = 30º angle of heel and not less than 0.09 m.rad up to θ = 40º or other angle of flooding θf footnoteif this angle is less than 40º Additionally, the area under the righting lever curve (GZ curve) between the angles of heel of 30º and 40º or between 30º and θf, if this angle is less than 40º, shall be not less than 0.03 m.rad;

    • .2 the righting lever GZ shall be at least 0.20 m at an angle of heel equal to or greater than 30º;

    • .3 the maximum righting arm shall occur at an angle of heel preferably exceeding 30º but not less than 25º; and

    • .4 the initial metacentric height GMo, corrected for free surface measured at 0º heel, shall be not less than 0.15 m.

  2 The requirements of paragraph 1 of this regulation shall be met through design measures. For combination carriers simple supplementary operational procedures may be allowed.

  3 Simple supplementary operational procedures for liquid transfer operations referred to in paragraph 2 of this regulation shall mean written procedures made available to the master which:

  • .1 are approved by the Administration;

  • .2 indicate those cargo and ballast tanks which may, under any specific condition of liquid transfer and possible range of cargo densities, be slack and still allow the stability criteria to be met. The slack tanks may vary during the liquid transfer operations and be of any combination provided they satisfy the criteria;

  • .3 will be readily understandable to the officer-in-charge of liquid transfer operations;

  • .4 provide for planned sequences of cargo/ballast transfer operations;

  • .5 allow comparisons of attained and required stability using stability performance criteria in graphical or tabular form;

  • .6 require no extensive mathematical calculations by the officer-in-charge;

  • .7 provide for corrective actions to be taken by the officer-in-charge in case of departure from recommended values and in case of emergency situations; and

  • .8 are prominently displayed in the approved trim and stability booklet and at the cargo/ballast transfer control station and in any computer software by which stability calculations are performed.

Parent topic: Part A - Construction
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