Section 25(3)(b) in The Merchant Shipping (Prevention of Pollution by Oil from Ships) Rules, 2010
(b)Where the double bottom does not extend for the full length and width of the tank involved, the double bottom is considered non-existent and the volume of the tanks above the area of the bottom damage shall be included in formula (II) even if the tank is not considered breached because of the installation of such a partial double bottom.