The following criteria are recommended for passenger and cargo ships.
- The area under the righting lever curve (GZ curve) should not be less than 0.055 metre-radian up to e = 30° angle of heel and not less than 0.09 metre-radian up to 9 = 40° or the 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 30° and 40° or between 30° and θf , if this angle is less than 40°, should not be less than 0.03 metre-radian.
- The righting lever GZ should be at least 0.20 m at an angle of heel equal to or greater than 30°.
- The maximum righting arm should occur at an angle of heel preferably exceeding 30° but not less than 25°.
- The initial metacentric height GMo should not be less than 0.15
- In addition, for passenger ships, the angle of heel on account of crowding of passengers to one side as defined should not exceed 10 degree.
- Where anti-rolling devices are installed in a ship, the Administration should be satisfied that the above criteria can be maintained when the devices are in operation.
- In addition, for passenger ships, the angle of heel on account of turning should not exceed 10 degree when calculated using the following.
For timber deck cargo ship
For ships loaded with timber deck cargoes and provided that the cargo extends longitudinally between superstructures (where there is no limiting superstructure at the after end, the timber deck cargo should extend at least to the after end of the aftermost hatchway) transversely for the full beam of ship after due allowance for a rounded gunwale not exceeding 4% of the breadth of the ship and/or securing the supporting uprights and which remains securely fixed at large angles of heel, the Administration may apply the following criteria .