INTERNATIONAL CONVENTION SAFETY OF LIFE AT SEA. 249 



(5) The margin line is a line drawn parallel to the bulkhead deck at side line, and 76 

 millimeters (equivalent to 3 inches) below the upper surface of that deck at side. 



(6) The draught is the vertical distance from the top of keel amidships to the load 

 water line. 



(7) The freeboard is the vertical distance from the load water line to the margin line 

 amidships. ] ■ , , v 



(8) The depth of the vessel is the sum of the draught and freeboard as above defined. 



(9) The sheer of the bulkhead deck at any point is the vertical distance between the 

 beam at side line at that point and a line drawn parallel to the load water line at the height 

 of the beam at side line amidships. 



(10) If block coefficient of fineness of displacement to load zvater line is used, this co- 

 efficient shall be determined as follows: 



Volume of displacement to molded lines. 



Length X Breadth X Draught. 



(11) The permeability of a space is the percentage of that space which can be occu- 

 pied 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 extreme 

 main transverse watertight bulkheads bounding the spaces devoted to the main and auxil- 

 iary propelling machinery, including boilers when installed. 



Article VI. 



FLOODABLE LENGTH. 



The floodable length at any point of the vessel shall be determined taking into con- 

 sideration the 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 hereafter 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 qu8stion, 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; 



