A—l 6

(c) (i) In the case of a ship not having a continuous bulkhead deck, the floodable length at any point may be determined to an assumed continuous margin line which at no point is less than 3 inches (or 76 millimetres) below the top of the deck (at side) to which the bulkheads concerned and the shell are carried watertight. (ii) Where a portion of an assumed margin line is appreciably below the deck to which bulkheads are carried, the Administration may permit a limited relaxation in the watertightness of those portions of the bulkheads which are above the margin line and immediately under the higher deck. Regulation 4 Permeability (a) The definite assumptions referred to in Regulation 3 relate to the permeabilities of the spaces below the margin line. In determining the floodable length, a uniform average permeability shall be used throughout the whole length of each of the following portions of the ship below the margin line : (i) The machinery space as defined in Regulation 2 ; (ii) The portion forward of the machinery space ; and (iii) The portion abaft the machinery space. (b) (i) For steamships the uniform average permeability throughout the machinery space shall be determined from the formula—--80 + 12-5 where a = volume of the passenger spaces, as defined in Regulation 2, 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 fine. (ii) For ships propelled by internal combustion engines, the uniform average permeability shall be taken as 5 greater than that given by the above formula. (iii) 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 calculation value may be used. For the purpose of such calculation, the permeabilities of passenger spaces, as defined in Regulation 2, 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 by the Administration. (c) Except as provided in paragraph (d) below, the uniform average permeability throughout the portion of the ship before (or abaft) the machinery space shall be determined from the formula — a 63 + 35 where : v a = volume of the passenger spaces, as defined in Regulation 2, which are situated below the margin line, before (or abaft) the machinery space, and v = whole volume of the portion of the ship below the margin fine before (or abaft) the machinery space.

25