(13) The condition of equilibrium
after flooding shall be regarded as satisfactory provided:
(a) The final waterline after flooding, taking
into account sinkage, heel and trim, is below the lower edge of any
opening through which progressive downflooding may take place. Such
openings shall include air pipes, ventilators and openings which are
closed-by means of weathertight doors (even if they comply with regulation 12) or hatch covers (even if they
comply with regulation 16 or 19(4)), and may exclude those openings closed
by means of manhole covers and flush scuttles (which comply with regulation 18), cargo hatch covers of the type
described in regulation 27(2), remotely
operated sliding watertight doors, and side scuttles of the non-opening
type (which comply with regulation 23).
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.
(b) If pipes, ducts or tunnels are situated within
the assumed extent of damage penetration as defined in paragraph 12(b) of this Regulation,
arrangements are to be made so that progressive flooding cannot thereby
extend to compartments other than those assumed to be floodable in
the calculation for each case of damage.
(c) The angle of heel due to unsymmetrical flooding
does not exceed 15 degrees. If no part of the deck is immersed, an
angle of heel of up to 17 degrees may be accepted.
(d) The metacentric height in the flooded condition
(e) When any part of the deck outside the compartment
assumed flooded in a particular case of damage is immersed, or in
any case where the margin of stability in the flooded condition may
be considered doubtful, the residual stability is to be investigated.
It may be regarded as sufficient if the righting lever curve has a
minimum range of 20 degrees beyond the position of equilibrium with
a maximum righting lever of at least 0.1 metre (4 inches) within this
range. The area under the righting lever curve within this range shall
be not less than 0.0175 metre-radians (0.689 inch-radians). The Administration
shall give consideration to the potential hazard presented by protected
or unprotected openings which may become temporarily immersed within
the range of residual stability.
(f) The Administration is satisfied that the stability
is sufficient during intermediate stages of flooding.