Section 5 Extent of Damage

501. Surface units

1. In assessing the damage stability of surface units, the following extent of damage should be as- sumed to occur between effective watertight bulkheads:

(1) horizontal penetration: 1.5 m; and

(2) vertical extent: from the base line upwards without limit.

2. The distance between effective watertight bulkheads or their nearest stepped portions which are positioned within the assumed extent of horizontal penetration should be not less than 3 m; where there is a lesser distance, one or more of the adjacent bulkheads should be disregarded.

3. Where damage of a lesser extent than in Par 1 results in a more severe condition, such lesser ex- tent should be assumed.

4. All piping, ventilation systems, trunks, etc., within the extent of damage referred to in Par 1 should be assumed to be damaged. Positive means of closure should be provided at watertight boundaries to preclude the progressive flooding of other spaces which are intended to be intact.

5. The compartments bounded by the bottom shell are to be considered flooded individually.

502. Self-elevating units

1. In assessing the damage stability of self-elevating units, the following extent of damage should be assumed to occur between effective watertight bulkheads:

(1) horizontal penetration: 1.5 m; and

(2) vertical extent: from the base line upwards without limit.

2. The distance between effective watertight bulkheads or their nearest stepped portions which are positioned within the assumed extent of horizontal penetration should be not less than 3 m; where there is a lesser distance, one or more of the adjacent bulkheads should be disregarded.

3. Where damage of a lesser extent than in Par 1 results in a more severe condition, such lesser ex- tent should be assumed.

4. Where a bottom mat is fitted, assumed damage penetration simultaneous to both the mat and the upper hull need only be considered when the lightest draught allows any part of the mat to fall within 1.5 m vertically of the waterline, and the difference in horizontal dimension of the upper hull and mat is less than 1.5 m in any area under consideration.

5. All piping, ventilation systems, trunks, etc., within the extent of damage referred to in Par 1 should be assumed to be damaged. Positive means of closure should be provided at watertight boundaries to preclude the progressive flooding of other spaces which are intended to be intact.

6. Positive means of closure are to be provided to preclude progressive flooding of other intact spaces.

7. The compartments adjacent to the bottom shell are also to be considered flooded individually.

8. The recessed ends and sides of drilling slot need not be subject to horizontal penetration if warning signs be posted on each side of the vessel stating that no boats be allowed inside the drilling slot. Instructions to this effect are to be included in the Operating Booklet.

503. Column-stabilized units

1. In assessing the damage stability of column-stabilized be assumed:

(1) Only those columns, underwater hulls and braces sumed to be damaged and the damage should be umns, underwater hulls and braces.

units, the following extent of damage should on the periphery of the unit should be as-

assumed in the exposed portions of the col-

(2) Columns and braces should be assumed to be flooded by damage having a vertical extent of 3 m occurring at any level between 5 m above and 3 m below the draughts specified in the op- erating manual. Where a watertight flat is located within this region, the damage should be as- sumed to have occurred in both compartments above and below the watertight flat in question. Lesser distances above or below the draughts may be applied to the satisfaction of the Society,

taking into account the actual operating conditions. However, the

required damage region should

extend at least 1.5 m above and below the draught specified in the operating manual.

(3) No vertical bulkhead should be assumed to be damaged, except where bulkheads are spaced

closer than a distance of one eighth of the column perimeter at the draught under consideration, measured at the periphery, in which case one or more of the bulkheads should be disregarded.

(4) Horizontal penetration of damage should be assumed to be 1.5 m.

(5) Underwater hull or footings should be assumed to be damaged when operating in a transit con- dition in the same manner as indicated in (1), (2), (4) and either (3) or (7), having regard to

their shape.

(6) If damage of a lesser extent than specified in (1) to (5) results in a more severe damage equili- brium condition, such a lesser extent is to be assumed.

(7) All piping, ventilation systems, trunks, etc., within the extent of damage should be assumed to

be damaged. Positive means of closure should be provided at watertight boundaries to preclude the progressive flooding of other spaces which are intended to be intact.