Ingangsdatum: 14-06-2013
Appendix - Definitions and interpretations
1 A stability instrument is an instrument
installed on board a particular ship by means of which it can be
ascertained that stability requirements specified for the ship
in the Stability Booklet are met in any operational loading
condition. A stability instrument comprises hardware and
software.
2 There are three types of
stability software, details of which are provided in chapter 4
of part B of the 2008 IS Code and MSC.1/Circ.1229. A brief
description of the three types is as follows. Three types of
calculations performed by stability software are acceptable
depending upon a ship's stability requirements:
Type 1: Software calculating intact
stability only (for ships not required to meet a damage
stability criterion);
Type 2: Software calculating intact
stability and checking damage stability on the basis of a
limit curve (e.g. for ships which apply to SOLAS chapter
II-1, part B-1 damage stability calculations, etc.) or
previously approved loading conditions; and
Type 3: Software calculating intact
stability and damage stability by direct application of
pre-programmed damage cases for each loading condition (for
some tankers, etc.).
3 Approved loading condition
3.1 In relation to a tanker
certified under MARPOL Annex I or the IBC or IGC Codes, an
approved loading condition is a unique individual condition
of loading, taking account of the combination of lightship
and all individual deadweight items, which has been verified
by the Administration or RO acting on its behalf as
complying with both intact and damage stability criteria,
and is approved for use in the service of the ship.
3.2 The approval
of an individual loading condition is granted for the
purpose of loading to that unique condition and cannot be
taken to confer any acceptance or approval of other loading
conditions which vary from it, given that the margin of
compliance against the applicable intact or damage stability
criteria may be zero.
3.3 Loading
conditions which are verified in service and shown to lie
within the boundary of an approved range of loading
conditions or approved limiting KG/GM curves shall also be
regarded as approved loading conditions.
3.4 Loading conditions which are
verified using an approved stability instrument authorized
by the Administration or RO acting on its behalf should also
be regarded as approved loading conditions.
4 Loading "in accordance with", "closely to" or "not
significantly different from" an approved loading
condition
4.1 For tankers which do not have
an approved stability instrument, an approved range of
loading conditions or critical GM or KG data, which enable
damage stability verification of the live loading condition
to be made on board prior to departure, loading should
always be made strictly in accordance with an approved
loading condition unless the loading condition is first
verified as compliant by the Administration or RO acting on
its behalf prior to departure.
4.2 However, to permit practical
operation of such tankers, having regard to small variations
in cargo SG, stores and minor tank fillings, it is
considered necessary to permit some variation in loading
from an approved condition.
4.3 In this respect, it is
recommended that a vessel which loads within the boundary
provided by an approved pair of departure and arrival
conditions, derived from a fixed distribution of cargo and
ballast, may be considered to be loaded in accordance with
these conditions.
4.4 To satisfy this
recommendation, the live loading condition should fall
within the following limits:
displacement, to fall within the range of
displacements of the approved departure and arrival
conditions;
KG/GM (corrected for free surface) to fall below a
value determined by linear interpolation at the live
condition displacement between the approved
departure and arrival conditions used to verify
damage stability compliance; and
trim, to fall within the range of trims described
by those of the approved departure and arrival
conditions.
4.5 No further relaxations or deviation
should be allowed, unless specifically approved by the
Administration.
5 Approved range of loading conditions
5.1 It is acceptable to load to a
condition of loading which is defined within a range of
approved loading conditions.
5.2 For an approved range of
loading conditions to be valid it must offer a clear
indication how cargoes and ballast are to be loaded.
5.3 In this respect, all
parameters of loading defined within an approved range of
loading conditions must be fully complied with for a vessel
to be considered correctly loaded within it.