(c) The subdivision abaft the fore peak of ships less than 430 feet (131 meters) but not less than 260 feet (79 meters) in length and having a criterion numeral less than S, and of all ships less than 260 feet (79 meters) in length shall be governed by the factor unity, unless it is shown to the satisfaction of the Administration to be impracticable to comply with this factor in any part of the ship, in which case, the Administration may allow such relaxation as may appear to be justified, having regard to all the circumstances.

(d) The provisions of subparagraph (c) shall apply also to ships of whatever length, which are to be certified to carry a number of L2 (in feet)/L2 (in meters)

passengers exceeding 12 but not exceeding 7000

or 50, whichever is the less.

REGULATION V.-Special Rules Concerning Subdivision.

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(1) A compartment may exceed the permissible length determined by the rules of Regulation IV provided the combined length of each pair of adjacent compartments to which the compartment in question is common does not exceed either the floodable length or twice the permissible length, whichever is the less.

If one of the two adjacent compartments is situated inside the machinery space, and the second is situated outside the machinery space, and the average permeability of the portion of the ship in which the second is situated differs from that of the machinery space, the combined length of the two compartments shall be adjusted to the mean average permeability of the two portions of the ship in which the compartments are situated.

Where the two adjacent compartments have different factors of subdivision, the combined length of the two compartments shall be determined proportionately.

(2) In ships 430 feet (131 meters) in length and upwards, one of the main transverse bulkheads abaft the fore peak shall be fitted at a distance from the forward perpendicular which is not greater than the permissible length.

(3) A main transverse bulkhead may be recessed provided that all parts of the recess lie inboard of vertical surfaces on both sides of the ship, situated at a distance from the shell plating equal to one-fifth of the breadth of the ship, as defined in Regulation 1 (3), and measured at right angles to the centerline at the level of the deepest subdivision loadline.

Any part of a recess which lies outside these limits shall be dealt with as a step in accordance with the following paragraph.

(4) A main transverse bulkhead may be stepped provided that (a) the combined length of the two compartments, separated by the bulkhead in question, does not exceed 90 percent of the floodable length, or (b) additional subdivision is provided in way of the step to maintain the same measure of safety as that secured by a plane bulkhead. (5) Where a main transverse bulkhead is recessed or stepped, an equivalent plane bulkhead shall be used in determining the subdivision.

(6) If the distance between two adjacent main transverse bulkheads, or their equivalent plane bulkheads, or the distance between the transverse planes passing through the nearest stepped portions of the bulkheads, is less than 10 feet (3.05 meters) plus 2 percent of

the length of the ship, only one of these bulkheads shall be regarded as forming part of the subdivision of the ship in accordance with the provisions of Regulation IV.

(7) Where a main transverse watertight compartment contains local subdivision and it can be shown to the satisfaction of the Administration that, after any assumed side damage extending over a length of 10 feet (3.05 meters) plus 2 percent of the length of the ship, the whole volume of the main compartment will not be flooded, a proportionate allowance may be made in the permissible length otherwise required for such compartment.

In such a case the volume of effective buoyancy assumed on the undamaged side shall not be greater than that assumed on the damaged side.

(8) Where it is proposed to fit watertight decks, inner skins or longitudinal bulkheads, watertight or nonwatertight, the Administration shall be satisfied that the safety of the ship will not be diminished in any respect, particularly having in view the possible listing effect of flooding in way of such structural arrangements. REGULATION VI. - Peak and Machinery Space Bulkheads, Shaft Tunnels, etc.

(1) Every ship shall have a forepeak or collision bulkhead, which shall be watertight up to the bulkhead deck. This bulkhead shall be fitted not less than 5 percent of the length of the ship, and not more than 10 feet (3.05 meters) plus 5 percent of the length of the ship from the forward perpendicular.

If the ship has a long forward superstructure, the forepeak bulkhead shall be extended weathertight to the deck next above the bulkhead deck. The extension need not be fitted directly over the bulkhead below, provided it is at least 5 percent of the length of the ship from the forward perpendicular, and the part of the bulkhead deck which forms the step is made effectively weathertight.

(2) An afterpeak bulkhead, and bulkheads dividing the machinery space, as defined in Regulation I (8), from the cargo and passenger spaces forward and aft, shall also be fitted and made watertight up to the bulkhead deck. The afterpeak bulkhead may, however, be stopped below the bulkhead deck, provided the degree of safety of the ship as regards subdivision is not thereby diminished.

(3) In all cases stern tubes shall be enclosed in watertight spaces. The stern gland shall be situated within a watertight shaft tunnel or other space of such volume that if flooded by leakage through the stern gland the margin line will not be submerged.

REGULATION VII.-Assigning, Marking, and Recording of Subdivision Loadlines.

(1) The subdivision loadlines assigned and marked under the provisions of Article 5 of the Convention shall be recorded in the Safety Certificate, and shall be distinguished by the notation C.1 for the principal passenger condition, and C.2, Č.3, etc., for the alternative conditions.

(2) The freeboard corresponding to each of these loadlines inserted in the Safety Certificate shall be measured at the same position and from the same deck line as the freeboards determined by recognized national freeboard regulations.

(3) In no case shall any subdivision loadline mark be placed above the deepest loadline in salt water as determined by the strength of the ship and/or recognized national freeboard regulations.

(4) Whatever may be the position of the subdivision loadline marks, a ship shall in no case be loaded so as to submerge the loadline mark appropriate to the season and locality as determined by the recognized national freeboard regulations.

REGULATION VIII.—Construction and Initial Testing of Watertight Bulkheads, Etc.

(1) Watertight subdivision bulkheads, whether transverse or longitudinal, 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 in way of each bulkhead. The construction of these bulkheads shall be to the satisfaction of the Administration.

(2) Steps and recesses in bulkheads shall be watertight and as strong as the bulkhead at the place where each occurs.

Where frames or beams pass through a watertight deck or bulkhead, such deck or bulkhead shall be made structurally watertight without the use of wood or cement.

(3) Testing main compartments by filling them with water is not compulsory. A complete examination of the bulkheads shall be made by a surveyor; and, in addition, a hose test shall be made in all cases. (4) The forepeak shall be tested with water to a head up to the deepest subdivision loadline.

(5) Double bottoms, including duct keels, and inner skins are to be subjected to a head of water up to the margin line.

(6) Tanks which are intended to hold liquids, and which form part of the subdivision of the ship, shall be tested for tightness with water to a head up to the deepest subdivision loadline or to a head corresponding to two-thirds of the depth from the top of keel to the margin line in way of the tanks, whichever is the greater; provided that in no case shall the test head be less than 3 feet (0.92 meter) above the top of the tank.

REGULATION IX.-Openings in Watertight Bulkheads.

(1) The number of openings in watertight bulkheads shall be reduced to the minimum compatible with the design and proper working of the ship; satisfactory means shall be provided for closing these openings.

(2) (a) Where pipes, scuppers, electric-light cables, etc., are carried through watertight subdivision bulkheads, arrangements shall be made to ensure the integrity of the watertightness of the bulkheads. (b) Sluice valves shall not be permitted in the watertight sub

division bulkheads.

(3) (a) No doors, manholes, or access openings are permitted(i) in the collision bulkhead below the margin line; (ii) in watertight transverse bulkheads dividing a cargo space from an adjoining cargo space or from a permanent or reserve bunker, except as provided in paragraph (7).

(b) The collision bulkhead may be pierced below the margin line by not more than one pipe for dealing with fluid in the forepeak tank, provided that the pipe is fitted with a screwdown valve capable

of being operated from above the bulkhead deck, the valve chest being secured inside the forepeak to the collision bulkhead.

(4) (a) Watertight doors fitted in bulkheads between permanent and reserve bunkers, shall be always accessible, except as provided in subparagraph 9 (b) for between deck bunker doors.

(b) Satisfactory arrangements shall be made by means of screens or otherwise, to prevent the coal from interfering with the closing of watertight bunker doors.

(5) Within the machinery space and apart from bunker and shaft tunnel doors, not more than one door may be fitted in each main transverse bulkhead for intercommunication. These doors shall be

located so as to have the sills as high as practicable.

(6) (a) The only types of watertight doors permissible are hinged doors, sliding doors, and doors of other equivalent patterns, excluding plate doors secured only by bolts.

(b) A hinged door shall be fitted with catches workable from each side of the bulkhead.

(c) A sliding door may have a horizontal or vertical motion. If required to be hand operated only, the gearing shall be capable of being worked at the door itself and also at an accessible position above the bulkhead deck.

(d) If a door is required to be closed by dropping or by the action of a dropping weight, it shall be fitted with a suitable arrangement to regulate the closing movement, and the gearing shall be so arranged that the door can be released both at the door itself and at an accessible position above the bulkhead deck. Hand gear shall also be provided, so arranged as to operate at the door itself and above the bulkhead deck, and also, so that after being disengaged for dropping, it can be quickly reengaged from either the upper or the lower position.

(e) If a door is required to be power operated from a central control, the gearing shall be so arranged that the door can be operated by power also at the door itself. The arrangements shall be such that the door will close automatically if opened by the local control after being closed from the central control, and also such that any door can be kept closed by local arrangements, which will prevent that door from being opened from the central control. Such power operated doors shall be provided with hand gear, workable both at the door itself and from an accessible position above the bulkhead deck.

(f) In all classes of doors indicators shall be fitted at all operating stations other than at the door itself, showing whether the door is opened or closed.

(7) (a) Hinged watertight doors in passenger, crew, and working spaces are only permitted above a deck, the underside of which, at its lowest point at side, is at least 7 feet (2.13 meters) above the deepest subdivision loadline, and they are not permitted in those spaces below such deck.

(b) Hinged watertight doors of satisfactory construction may be fitted in bulkheads dividing cargo between deck spaces, in levels in which side cargo doors would be permitted under the provisions of Regulation X (11). These doors shall be closed before the voyage commences and shall be kept closed during the voyage, and the time of opening such doors in port and of closing them before the ship

leaves port shall be entered in the official log book. Where it is proposed to fit such doors, the number and arrangements shall receive the special consideration of the Administration, and a statement shall be required from the owners certifying as to the absolute necessity of such doors.

(8) All other watertight doors shall be sliding doors.

(9) (a) When any watertight doors which may be sometimes opened at sea, excluding those at the entrances of tunnels, are fitted in the main transverse watertight bulkheads at such a height that their sills are below the deepest subdivision loadline, the following rules shall apply:

(I) When the number of such doors exceeds 5 all the watertight sliding doors shall be power operated and shall be capable of being simultaneously closed from a station situated on the bridge, simultaneous closing of these doors being preceded by a warning sound signal.

(II) When the number of such doors does not exceed 5—

(i) if the criterion numeral does not exceed 30, all the watertight sliding doors may be operated by hand only;

(ii) if the criterion numeral exceeds 30, but does not exceed 60, all the watertight sliding doors may be either dropping doors fitted with releasing and hand gear operated at the door and from above the bulkhead deck or doors operated by power;

(iii) if the criterion numeral exceeds 60, all the watertight sliding doors shall be operated by power.

(b) If watertight doors which have sometimes to be open at sea for the purpose of trimming coal are fitted between bunkers in the between decks below the bulkhead deck, these doors shall be operated by power. The opening and closing of these doors shall be recorded in the official log book.

(c) When trunkways in connection with refrigerated cargo are carried through more than one main transverse watertight bulkhead, and the sills of the openings are less than 7 feet (2.13 meters) above the deepest subdivision load line, the watertight doors at such openings shall be operated by power.

(10) Portable plates on bulkheads shall not be permitted except in machinery spaces. Such plates shall always be in place before the ship leaves port, and shall not be removed at sea except in case of urgent necessity. The necessary precautions shall be taken in replacing them to ensure that the joints shall be watertight.

(11) All watertight doors shall be kept closed during navigation except when necessarily opened for the working of the ship, and shall always be ready to be immediately closed.

(12) Where trunkways or tunnels for access from crew's accommodation to the stokehold, for piping, or for any other purpose are carried through main transverse watertight bulkheads, they shall be watertight and in accordance with the requirements of Regulation XII. The access to at least one end of each such tunnel or trunkway, if used as a passage at sea, shall be through a trunk extending watertight to a height sufficient to permit access above the margin line. The access to the other end of the trunkway or tunnel may be through a watertight door of the type required by its location in the ship.