2 Double Bottom

2.1 General

2.1.1 A double bottom need not be fitted in way of watertight tanks, including dry tanks of moderate size provided the safety of the ship is not impaired in the event of bottom or side damage as regulated in SOLAS II-1, Reg 9.

2.2 Extent of double bottom

2.2.1 For bulk carriers, a double bottom is to be fitted extending from the collision bulkhead to the aft peak bulkhead, as far as this is practicable and compatible with the design and proper working of the ship.

For oil tankers, a double bottom is to be fitted to protect the cargo hold region and pump rooms. However the double bottom below pump rooms may be omitted provided that it is in compliance with MARPOL, Annex I, Ch 4, Reg 22.

2.2.2 Where double bottom is required to be fitted, the inner bottom is to be continued out to the ship side in such a manner as to protect the bottom to the turn of the bilge in areas where hopper or double side spaces are not provided.

2.3 Height of double bottom

2.3.1 Unless otherwise specified, the height of the double bottom is not to be less than the lesser of:

• For oil tankers: B/15 or 2 m, however not less than 1.0 m measured at right angles to the shell plating at any cross section..
• For bulk carriers: B/20 or 2 m, however not less than 0.76 m measured vertically from the plane parallel with keel line to inner bottom.

2.4 Small wells in double bottom tank

2.4.1 Small wells constructed in the double bottom are not to extend in depth more than necessary. A well extending to the outer bottom, may, however, be permitted at the after end of the shaft tunnel of the ship. Other wells may be permitted by the Society if it is satisfied that the arrangements give protection equivalent to that afforded by a double bottom that complies with [2.1].