What is intact stability criteria for tankers?

Every oil tanker of 5,000 tonnes deadweight and above delivered on or after 1 February 2002, as defined, 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:
2.1the area under the righting lever curve (GZ curve) shall be not less than 0.055 m·rad up to θ = 30° angle of heel and not less than 0.09 m·rad up toθ = 40° or other angle of flooding θf  if this angle is less than 40°. Additionally, the area under the righting lever curve (GZ curve) between the angles of heel of 308 and 40° or between 30° and θf, if this angle is less than 40°, shall be not less than 0.03 m·rad;
2.2the righting lever GZ shall be at least 0.20 m at an angle of heel equal to or greater than 30°;
2.3the maximum righting arm shall occur at an angle of heel preferably exceeding 30° but not less than 25°; and
2.4the initial metacentric height GMo, corrected for free surface measured at 0° heel, shall be not less than 0.15 m.

2 The requirements of paragraph 1 of this regulation shall be met through design measures.

ANUBHAV GAUTAM