Part C
Watertight Integrity
12 Drainage of Weather Decks
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12.1 The weather deck on all vessels shall be watertight or fitted with closures to ensure watertight integrity. The drainage from the weather deck shall be such that the watertight integrity is not compromised.
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12.2 When a deck is fitted with bulwarks such that shipped water may be trapped, the bulwarks shall be provided with efficient freeing ports.
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12.3 The area of freeing ports shall be at least 5% of the bulwark area and be situated in the lower third of the bulwark height, the bottom of which shall be flush with the deck.
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12.4 A vessel of less than 12m in length, certified to operate in coastal waters, having a well deck aft and is fitted with bulwarks all round and which always operates with stern trim, may be provided with a minimum of two ports fitted (one port and one starboard) in the transom, each having a clear area of at least 225 sq.cm.
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12.5 Where a non-return shutter or flap is fitted to a freeing port it shall have sufficient clearance to prevent jamming and any hinges shall have pins or bearings of non-corrodible material. Normally, hinges shall be along the upper edge of the non-return shutter or flap.
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12.6 Where a vessel has side deck areas of less than one-tenth the length of the vessel, in which water can be trapped a smaller freeing port area may be accepted. The reduced area shall be based on the volume of water, which is likely to become trapped.
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12.7 In a vessel in which freeing ports cannot be fitted, other efficient means of clearing trapped water from the vessel shall be provided to the satisfaction of the Administration.
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12.8 Structures and spaces considered non-weathertight shall be provided with efficient drainage arrangements.
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12.9 Where cargo is to be stowed on deck the stowage arrangement shall be such as to not impede the free flow of water from the deck.
13 Air Pipes
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13.1 When located on the weather deck, air pipes shall be kept as far inboard as possible and have a height above deck sufficient to prevent downflooding when heeled in rough water.
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13.2 An airpipe of greater than 10mm inside diameter, serving a fuel or other tank shall be provided with a permanently attached means of weathertight closure.
14 Sea Inlets and Discharges
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14.1 An opening below the weather deck shall be provided with an efficient means of closure.
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14.2 When the opening is for the purpose of an inlet or discharge below a line drawn 150mm (6 inches) above the loading mark it shall be fitted with a seacock, valve or other positive means of closure, which is readily accessible in an emergency.
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14.3 When the opening is for a log or other sensor, which is capable of being withdrawn, it shall be fitted in an efficient watertight manner and provided with an effective means of closure when such a fitting is removed.
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14.4 Inlet and discharge pipes from water closets shall be provided with shell fittings as required by III/14. When the rim of a toilet is less than 300mm above the deepest waterline of the vessel, anti-syphon measures shall be provided.
15 Materials for Valves and Associated Piping
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15.1 A valve or similar fitting attached to the side of the vessel below the waterline, shall be normally of steel, bronze or other non- brittle fire resistant material or equivalent. Valves of ordinary cast iron or similar material are not acceptable.
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15.2 When plastic piping is used it shall be of good quality and of a type suitable for the purpose. Any such pipe shall be located so as to minimise the risk of accidental damage. Where fitted within an engine space or fire risk area, a means shall be provided to stop the ingress of water in the event of the pipe being damaged, operable from outside the space.