Intact Stability Criteria for Tankers

Intact Stability Criteria for Tankers

Every oil tanker of 5,000 tonnes deadweight and more delivered on or after 1 February 2002, shall comply with the intact stability criteria of Annex I, Chp. 4/ Reg 27, as appropriate, for any operating draught under the worst conditions of cargo and ballast loading, consistent with good operational practice, including intermediate stages of liquid transfer operations. Under every conditions the ballast tanks shall be assumed slack.

1. At 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, below criteria shall be applicable:

a. The 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 to θ = 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 not be less than 0.03 m·rad;

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

c. The maximum righting arm shall occur at an angle of heel preferably exceeding 30° but not less than 25°; and

d. The initial metacentric height GMo, corrected for free surface measured at 0° heel, shall be not less than 0.15 m.

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