a transverse or longitudinal bulkhead shall be considered intact if all parts of it lie inboard of vertical surfaces on both sides of the ship, which are situated at a distance from the shell plating equal to one-fifth of the breadth of the ship, as defined in Regulation II-1/2, and measured at right angles to the centreline at the level of the deepest subdivision load line;

in cases where the ship's hull is structurally partly widened for compliance with the provisions of this Annex, the resulting increase of the value of one fifth of the breadth of it is to be used throughout, but shall not govern the location of existing bulkhead penetrations, piping systems, etc., which were acceptable prior to the widening;

the tightness of transverse or longitudinal bulkheads which are taken into account as effective to confine the assumed accumulated sea water in the compartment concerned in the damaged ro-ro deck shall be commensurate with the drainage system, and shall withstand hydrostatic pressure in accordance with the results of the damage calculation. Such bulkheads shall be at least 4 m in height unless the height of water is less than 0,5 m. In such cases the height of the bulkhead may be calculated in accordance with the following:

• Bh = 8hw

  where:

  • Bh is the bulkhead height;

  • and hw is the height of water.

In any event, the minimum height of the bulkhead should be not less than 2,2 m. However, in case of a ship with hanging car decks, the minimum height of the bulkhead shall be not less than the height to the underside of the hanging deck when in its lowered position;

for special arrangements such as, e.g., full-width hanging decks and wide side casings, other bulkhead heights may be accepted on the basis of detailed model tests;

the effect of the volume of the assumed accumulated sea water need not be taken into account for any compartment of the damaged ro-ro deck, provided that such a compartment has on each side of the deck freeing ports evenly distributed along the sides of the compartment complying with the following:

1. 2.5.1.

   A ≥ 0,3 l

   where A is the total area of freeing ports on each side of the deck in m²; and l is the length of the compartment in m;

2. 2.5.2.

   the ship shall maintain a residual freeboard of at least 1,0 m in the worst damage condition without taking into account the effect of the assumed volume of water on the damaged ro-ro deck; and

3. 2.5.3.

   such freeing ports shall be located within the height of 0,6 m above the damaged ro-ro deck, and the lower edge of the ports shall be within 2 cm above the damaged ro-ro deck; and

4. 2.5.4.

   such freeing ports shall be fitted with closing devices or flaps to prevent water entering the ro-ro deck whilst allowing water which may accumulate on the ro-ro deck to drain.

When a bulkhead above the ro-ro deck is assumed damaged, both compartments bordering the bulkhead shall be assumed flooded to the same height of water surface as calculated in paragraph 1.1 or 1.3.