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April, 1914 purposes indicated in (a). If in a 'tween deck space enclosed by complete trans- verse permanent steel bulkheads any portion thereof is appropriated to pas- sengers, the whole of that space shall be regarded as passengér space; and, similarly, 'tween deck spaces -appro- priated for the carriage of either pas- sengers or cargo shall be regarded as passenger spaces. Where the spaces before or abaft the machinery space below the margin > line consist partly of spaces mentioned in section (a) and partly of spaces mentioned in section (b), the average percentage of permeability shall be determined separately for each end by the formula 95--35r, where r is the ratio between the volume of the spaces mentioned in section (a) and the total volume of the space in the portion of the ship under consideration. Sub-Division The permissible length of compart- ments is stated in Article VIII of the regulations. The maximum permissi- ble length of one compartment hav- ing its center at any point in the ship's length is obtained from the floodable length by multiplying that length by an appropriate factor, called the fac- tor of sub-division. This factor of sub-division depends on the length of the ship, and,. for <a "given. Jength, varies according to the nature of the service for which the ship is intended. The factor decreases in a regular and continuous manner-- (a) As the length of ship increases; and (b) As. for .a given (aon the ship departs from the type of ship en- gaged in a mixed cargo and passenger service, and approaches to the type of ship primarily engaged in the carriage of passengers. For each of the two types of ships referred to in (b) the variation of the factor of sub-division may be ex- pressed by a curve, of which the co-ordinates represent. the length of the ship and the value of the fac- tor. Table I gives certain points on two curves, the higher of which cor- responds to the minimum requirements for the "mixed" type, and the lower to the. minimum requirements for the "passenger" type. WARES ©. A ----B Metres. Feet. Metres. Feet. 1.00 90 .- 295 79 259 0.90 114 374 87 285 0.84 23 404 93 305 0.65 149 ARO es LEG 380 0.50 174 571 149: AS 0.39 Bas 699 209 685 0.34 274 899 274 8c9 Column A gives the missible values of the factor of sub- division for the length of ships given "in columns B and C. Column B is maximum per- THE MARINE REVIEW applicable to ships engaged in a mixed cargo and passenger service, and column C js applicable to ships primarily engaged in the carriage of passengers, For a given length of value of a factor of sub-division appropriate to a ship between the two extreme lim- its will be between the values of the _factors determined by the two curves mentioned above, and will be auto- matically fixed by a criterion of ser- vice which is to form the subject of further study. When the factor of sub-division is equal to or less than 5, it may be doubled in order to give at any point of the ship's length the total length of two adjacent compart- ments; but, in that case, the length of the shorter compartment of any pair shall not be less than one-quar- ter of the total length so obtained. If one of the two adjacent compart- ments is situated inside the machinery space and the second is situated out- side the machinery space, and the average permeability of the por- tion of the ship in which the second is situated differs from 80 per cent, the length of the pair of compartments shall be adjusted to the proper value by applying a suitable correction. In no.case what- ever shall the length of any water- tight compartment exceed 92 ft. When tthe factor of sub-division applicable to any ship is less than 0.84, but more than 0.5, the combined length of the two foremost compart- ments shall not exceed the floodable length at the extreme forward end, provided also that the length of the second compartment is not greater than that permissible by Article VIII and not less .than 10 ft. When the ship is more than 699 ft. long and less than 823 ft., the floodable length at the forward end of the ship shall be at least 20 per cent of the ship's length; and the ship, forward of a bulkhead placed either at the distance of the actual floodable length abaft the stem or not nearer to the stem than 20 per cent of the ship's length, shall be di- vided into at least three compartments. When the length of the ship is equal to or greater than 823 ft. the same method shall be adopted, but the floodable length shall be at least 28 per cent and the number of compart- 'ments at least four. cd Bulkheads, Etc. A bulkhead may be recessed trans- versely, provided the sides of the recess are at a sufficient distance from the sides of the ship. Vertical steps are inadmissible in the main trans- verse watertight bulkheads of ships to which the sub- division rules of Arti- 137 cle VIII apply where the factor of sub-division is greater than 0.5, unless such arrangements are made by addi- tional sub-division as shall maintain the same measure of safety as that se- cured by bulkheads without steps. The total length of the steps in any bulk- head shall not exceed 2 per cent of the ship's length, plus 10 ft. The ex- istence of recesses or steps in a bulk- - head shall in no case affect the per- missible volumes of the compart- ments adjacent to such bulkhead. Article © X11. of * the regulations states that in the parts of a ship above the margin line there shall be fitted fireproof bulkheads which will serve to retard the spread of fire. The mean distance between any two consecutive bulkheads of this description shall not be greater than 131 ft. Recesses in these bulkheads shall be fireproof, and the openings in these bulkheads shall be fitted with fireproof doors. Means of Escape In passenger and crew spaces a practicable means of escape for the occupants shall be provided from each watertight compartment, and_ there shall be a means of escape for the crew from each engine room, shaft tunnel and stokehold compartment independ- ent of the watertight doors. In order to insure their strength and watertightness, watertight bulk- heads shall be constructed and tested in accordance with the provisions of Article XIV of the regulations, _which states :-- > (1) Watertight bulkheads shall be constructed in such a manner that they shall be capable of supporting with a proper margin of resistance, the pressure due to a head of water up 'to the margin line. (2) Steps and recesses in bulk- heads shall be as watertight and as strong as the bulkhead at me place where each occurs. Where frames or beams pass through a watertight deck or bulkhead, the watertightness shall be obtained by caulked angle chocks, or cast iron or steel chocks efficiently secured and rust-joined, and not by wood or ce- ment. (3) Testing main compartments by filling them with water is not com- pulsory. A complete examination of the bulkheads shall be made by a sur- veyor; and, in addition, a hose test shall be made in all cases. (4) The foremost and aftermost compartments shall be tested with wa- ter to a head up to the margin line. Double bottoms, deep tanks, and all compartments intended to hold liquids shall be tested with water to a head 8 feet above the top of the tank or