Subdivision
30.—(1)  A main transverse bulkhead may be recessed or stepped where additional subdivision is provided in way of the recess or step to maintain the same measure of safety as that secured by a plane bulkhead.
(2)  Where a main transverse bulkhead is recessed or stepped, an equivalent plane bulkhead shall be used in determining the subdivision.
(3)  Where a main transverse watertight compartment contains local subdivision and it can be shown to the satisfaction of the Director that, after any assumed side damage the whole volume of the main compartment will not be flooded, a proportionate allowance may be made in the permissible length otherwise required for such compartment. In such a case the volume of effective buoyancy assumed on the undamaged side shall not be greater than that assumed on the damaged side.