52.1 The vessel should be loaded with all cargo
tanks filled to a level corresponding to the maximum combined total
of vertical moment of volume plus free surface inertia moment at 0°
heel, for each individual tank. Cargo density should correspond to
the available cargo deadweight at the displacement at which transverse
KM reaches a minimum value, assuming full departure consumables and
1% of the total water ballast capacity. The maximum free surface moment
should be assumed in all ballast conditions. For the purpose of calculating
GM0, liquid free surface corrections should be based on
the appropriate upright free surface inertia moment. The righting
lever curve may be corrected on the basis of liquid transfer moments.
52.2 For proving compliance with regulation 27 of Annex I to MARPOL,
as an alternative to the loading case described in MARPOL Unified
Interpretation 45.1 it is accepted to carry out an extensive analysis
covering all possible combinations of cargo and ballast tank loading.
For such extensive analysis conditions, it is considered that:
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.1 weight, centre of gravity coordinates and free
surface moment for all tanks should be according to the actual content
considered in the calculations; and
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.2 the extensive calculations should be carried
out in accordance with the following:
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.2.1 the draughts should be varied between light
ballast and scantling draught;
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.2.2 consumables including but not restricted
to fuel oil, diesel oil and fresh water corresponding to 97%, 50%
and 10% content should be considered;
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.2.3 for each draught and variation of consumables,
the available deadweight should comprise ballast water and cargo,
such that combinations between maximum ballast and minimum cargo and
vice versa are covered. In all cases, the number of ballast and cargo
tanks loaded should be chosen to reflect the worst combination of
VCG and free surface effects. Operational limits on the number of
tanks considered to be simultaneously slack and exclusion of specific
tanks should not be permitted. All ballast tanks should have at least
1% content;
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.2.4 cargo densities between the lowest and highest
intended to be carried should be considered; and
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.2.5 sufficient steps between all limits should
be examined to ensure that the worst conditions are identified. A
minimum of 20 steps for the range of cargo and ballast content, between
1% and 99% of total capacity, should be examined. More closely spaced
steps near critical parts of the range may be necessary.
At every stage the criteria described in paragraph 1 of regulation 27 should be met.