14 SAFETY OF LIFE AT SEA. APPLICATION OF SUBDIVISION 



1 1 . The permeability of a space is the percentage of that space which can be 

 occupied by water. 



The volume of a compartment which extends above the margin line shall be 

 measured only to the height of that line. Volumes shall be understood as volumes 

 to molded lines. 



12. The machinery space is to be taken as extending in length between the ex- 

 treme main transverse watertight bulkheads bounding the spaces devoted to the 

 main and auxiliary propelling machinery, including boilers when installed. 



Article VI. — Floodahle Length. 



The floodable length at any point of the length of a vessel shall be deter- 

 mined taking into consideration form, draught, and other limiting characteristics 

 of the vessel in question. 



This floodable length for a given point in a vessel with a continuous bulkhead 

 deck is the maximum percentage of the length of the vessel (having its center at 

 the point in question) which can be flooded under the definite assumptions here- 

 after set forth in Article VII without the vessel being submerged beyond the 

 margin line. 



In the case of vessels not having a continuous bulkhead deck, the floodable 

 length must be such as to secure to the vessel in question, for each portion of its 

 length, and for all conditions of trim after damage, a measure of safety at least 

 equal in effectiveness to that laid down for the vessel with continuous bulkhead 

 deck. 



Article VII. — Permeability. 



The definite assumptions referred to in Article VI relate to the permeabilities 

 of the spaces in question below the margin line. 



In determining the floodable length a uniform average permeability shall be 

 used throughout the whole length of each of the three following portions of the 

 vessel : — 



1. The machinery space. 



2. The portion forward of the machinery space. 



3. The portion abaft the machinery space. 



For steam vessels the permeability of the machinery space, including the 

 double bottom in wake thereof, shall be taken as 80 per cent. For vessels fitted 

 with internal-combustion engines the corresponding permeability shall be taken as 

 85 per cent, unless it is proved by actual calculation that a lower figure may be 

 adopted, provided that in no case shall that figure be less than 80 per cent. 



The permeabilities for spaces forward and aft of the machinery space shall be 

 as follows: — 



(a) Sixty per cent in cargo spaces, bunkers (permanent or reserve), store- 

 rooms, baggage and mail rooms, chain lockers, watertight shaft or pipe tunnels, and 

 fresh-water tanks above the double bottom. 



