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SCHEDULE 1
SUBDIVISION and CRITERIA FOR STABILITY AFTER DAMAGE

1. Double hull ^

1.1 Where waste is carried on a ship, it must be separated by an intermediate compartment of not less than 750 millimetres in depth or breadth from the moulded surface of the outer shell plating.

2. Flooding ^

2.1 Every ship must in any Arctic operating condition be able to withstand the flooding due to hull penetration resulting from ice damage anywhere on the hull having the extent set out in paragraph 2.2 and must remain in a satisfactory condition of equilibrium after such damage.

2.2 The hull penetration patch due to ice damage to be used in calculations to ensure compliance with paragraph 2.1 is a rectangle which must extend

• 5 metres spaced equally forward and aft from the centre of the assumed damage along a line parallel to the waterline before damage,
• 5 metres measured on the girth equally above and below the line of the centre of damage, and
• 750 millimetres in depth measured inboard from the moulded line of the shell, and normal to the shell, for the full extent of the patch .

Figure 1 ^

Illustration of damage patch

2.3 If lesser extents of damage would have greater adverse effect on the equilibrium of the vessel than the damage described in 2.2, the necessary calculations to ensure compliance with paragraph 2.1 must also be based on those lesser extents of damage.

3. Criteria for equilibrium ^

3.1 A satisfactory condition of equilibrium, is a condition with a positive metacentric height of not less than 150 mm, an area under the righting lever curve of not less than 0.055 metre-radians, a positive range under the righting lever curve beyond the position of equilibrium of not less than 20 degrees; and a freeboard at any position of not less than one third of the intact freeboard at that position or, 50 per cent of the design limiting ice thickness for the ship where this can be determined.

3.2 The maximum angle of heel due to unsymmetrical flooding after damage and after any automatic equalisation measures have been completed is not to exceed 17 degrees. Equalisation measures requiring mechanical assistance are not to be used. Automatic cross-flooding arrangements must equalise in a period of not more than 15 minutes. All pipes, ducts and tunnels within a 750 mm distance from the side shell must be considered damaged, and arrangements must be made as necessary to prevent progressive flooding to compartments other than those assumed to be floodable in the calculation for each case of damage. All doors in watertight bulkheads must be of the sliding type to be considered as intact. However in the case of doors separating a main machinery space from a steering gear compartment. watertight doors may be of a hinged, quick acting type kept closed at sea, whilst not in use, provided also that the lower sill of such doors is above the summer load waterline, and that the door is located near the centreline of the vessel.

3.3 The transitory conditions during flooding resulting from the damage specified in sections 2.2 and 2.3 must be considered when making calculations to ensure compliance with section 3.1. During all stages of flooding and cross-flooding a positive metacentric height of not less than 50 millimetres must be maintained, calculated on the basis of lost buoyancy.

4. Ramming stability ^

4.1 Every ship must be constructed such that during any ram when the ship is riding up and sliding off the ice, and at the end of any such ram,

• the ship is in a state of stable equilibrium with a positive metacentric height of not less than 150 millimetres, and
• a line 150 mm below the deck edge of the freeboard deck, as defined in the applicable Load Line Regulations, does not submerge.

4.2 Depending on the fore end hull characteristics, the vessel is assumed to ride up onto the ice and remain momentarily poised at the lowest stem extremity as follows:

• for a regular stem profile, at the point at which the stem contour is tangent to the keel line;
• for a stem fitted with a structurally defined skeg, at the point at which the stem contour meets the top of the skeg,
• for a stem profile where the skeg is defined by shape alone, at the point at which the stem contour tangent intersects the ice horn tangent,
• for a stem profile of novel design, the position will be specially considered by Ship Safety.

5. Calculations ^

5.1 All calculations are to be made on the basis of trimmed hydrostatics appropriate to the initial and final conditions of the vessel, and to take full account of the effect of free surface.

5.2 The angle at which progressive flooding occurs will cut short the righting lever curve that is used for determining the area under the curve, the maximum righting lever (GZMAX) and the range of positive stability.

6. Permeability ^

6.1 The permeability of spaces may be assessed by direct calculation where this is appropriate. If insulation is contained in spaces for which consideration of direct calculation is requested, the insulation

• shall be impermeable to water under hydrostatic pressure at least corresponding to the pressure caused by the assumed flooding;
• shall not crush or break-up due to hydrostatic pressure at least corresponding to the pressure caused by the assumed flooding;
• shall be highly resistant to heat and be non-combustible;
• shall not deteriorate or change properties over the long term in the space in which it is to be installed onboard;
• shall be highly resistant to the action of hydrocarbons; and
• shall be adequately secured so it will remain in position if subjected to collision damage and displacement, distortion of its supporting and retaining structure, repeated rapid ingress and outflow of sea water and the buoyant forces caused by immersion following a flooding casualty.

7. Intact stability ^

7.1 Where ships are fitted with a heeling system, the deck edge shall not be immersed when the vessel is heeled to 5 degrees beyond the design maximum heel, or 15 degrees, whichever is the greater, when floating at the deepest ice operating waterline,

7.2 In all respects, the intact stability of the ship shall meet the stability criteria set out

• for Canadian ships, in the document "Stability, Subdivision and Load Line Standards" TP 7301, as amended from time to time; and
• for foreign ships as required by their national administration.

8. Submission of stability information ^

8.1 Before a ship operates in the Canadian Arctic, copies of all calculations and all other necessary information to demonstrate compliance with the criteria are to be submitted to Ship Safety.

8.2 All information submitted is to be in either English or French. There shall also be included a copy of the lines plan .

8.3 All stability information on board the vessel is to be available in a language that all persons in charge of each deck watch can readily understand. All intact stability information is to include samples of manual methods of determining the stability characteristics of the vessel. The stability information is to contain details of typical service and ballast conditions, provision for evaluating other conditions of loading, a summary of the ship's survival capabilities and sufficient information to ensure that the ship is loaded and operated in a safe and seaworthy manner.

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