3.5.10 In assessing the damage stability of column-stabilized
units, the following extent of damage should be assumed:
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.1 Only those columns, underwater hulls and braces
on the periphery of the unit should be assumed to be damaged and the
damage should be assumed in the exposed portions of the columns, underwater
hulls and braces.
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.2 Columns and braces should be assumed to be
flooded by damage having a vertical extent of 3.0 m occurring at any
level between 5.0 m above and 3.0 m below the draughts specified in
the operating manual. Where a watertight flat is located within this
region, the damage should be assumed 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 Administration, 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.
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.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 .
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.4 Horizontal penetration of damage should be
assumed to be 1.5 m.
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.5 Underwater hull or footings should be assumed
to be damaged when operating in a transit condition in the same manner
as indicated in 3.5.10.1, 3.5.10.2, 3.5.10.4 and either 3.5.10.3 or
3.5.6, having regard to their shape.
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.6 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.