Section 28(2)(e) in The Merchant Shipping (Prevention of Pollution by Oil from Ships) Rules, 2010
(e)where the damage between adjacent transverse watertight bulkheads is envisaged as specified in clause (c) above, no main transverse bulkhead or a transverse bulkhead bounding side tanks or double bottom tanks shall be assumed damaged, unless-(i)the spacing of the adjacent bulkheads is less than the longitudinal extent of assumed damage specified in clause (a); or(ii)there is a step or recess in a transverse bulkhead of more than 3.05 m in length, located within the extent of penetration of assumed damage: