SAFETY OF LIFE AT SEA C21 



Regulation 4 



Permeability 



(a) The definite assumptions referred to in Regulation 3 of this Chapter 

 relate to the permeabilities of the spaces below the margin line. 



In determining the floodable length, a uniform average permeabiliity shall 

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

 ship below the margin hne : — 



(i) the machinery space as defined in Regulation 2 of this Chapter; 



(ii) the portion forward of the machinery space; and 

 (iii) the portion abaft the machinery space. 



(b) (i) The uniform average permeability throughout the machinery space 

 shall be determined from the formula^ 



85+10 



(^) 



where : — 



a = volume of the passenger spaces, as defined in Regulation 2 of this 

 Chapter, which are situated below the margin line within the limits 

 of the machinery space. 



c= volume of between deck spaces below the margin line within the limits 

 of the machinery space which are appropriated to cargo, coal or 

 stores. 



v= whole volume of the machinery space below the margin line. 



(ii) Where it is shown to the satisfaction of the Administration that the 

 average permeability as determined by detailed calculation is less than that 

 given by the formula, the detailed calculated value may be used. For the 

 purpose of such calculation, the permeabilities of passenger spaces, as defined 

 in Regulation 2 of this Chapter, shall be taken as 95, that of all cargo, coal 

 and store spaces as 60, and that of double bottom, oil fuel and other tanks at 

 such values as may be approved in each case. 



(c) Except as provided in paragraph (d) of this Regulation, the uniform 

 average permeability throughout the portion of the ship before (or abaft) the 

 machinery space shall be determined from the formula — 



• 63 + 35 — 



V 



where : 



a = volume of the passenger spaces, as defined in Regulation 2 of this 

 Chapter, which are situated below the margin line, before (or abaft) 

 the machinery space, and 



Ch. 2 



