(1) The following minimum stability criteria shall
be met unless the Administration is satisfied that operating experience
justifies departures therefrom:
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(a) the area under the righting level curve (GZ curve) shall not be less than 0.055 m-rad up to 30° angle
of heel and not less than 0.090 m–rad up to 40° or the angle
of flooding θf if this angle is less than 40°.
Additionally, the area under the righting level curve (GZ curve)
between the angles of heel of 30° and 40° or between 30°
and θf, if this angle is less than 40° shall
not be less than 0.030 m-rad. θf is the angle of
heel at which openings in the hull, superstructure or deckhouses which
cannot rapidly be closed weathertight commence to immerse. In applying
this criterion, small openings through which progressive flooding
cannot take place need not be considered as open;
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(b) the righting level GZ shall be
at least 200 mm at an angle of heel equal to or greater than 30°;
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(c) the maximum righting level GZ
max shall occur at an angle of heel preferably exceeding 30°
but not less than 25°;
-
(d) the initial metacentric height GM shall
not be less than 350 mm for single deck vessels. In vessels with complete
superstructure or vessels of 70 m in length and over the metacentric
height may be reduced to the satisfaction of the Administration but
in no case shall be less than 150 mm.
(2) Where arrangements other than bilge keels
are provided to limit the angles of roll, the Administration shall
be satisfied that the stability criteria given in paragraph (1) are
maintained in all operating conditions.
(3) Where ballast is provided to ensure compliance
with paragraph (1), its nature and arrangement shall be to the satisfaction
of the Administration.