Circular Letter
MSC/Circ.1159
GUIDELINES ON THE PROVISION OF STABILITY-RELATED INFORMATION FOR BULK CARRIERS
(adopted on 24 May 2005)
1.
The Maritime Safety Committee (MSC), at its seventy-sixth session (2 to 13
December 2002), having considered the results of various FSA studies on bulk
carrier safety, agreed that the risk control option calling for the provision
of detailed, comprehensive and user-friendly information covering stability and
strength characteristics of the ship’s hull during loading and unloading should
be applied to new bulk carriers. Furthermore, MSC 76 noted that the
above-mentioned risk control option was more relevant for smaller ships with
respect to stability and for larger ships with respect to structural strength,
and instructed the Sub-Committee on Stability and Load Lines and on Fishing
Vessels Safety (SLF) and the Sub-Committee on Ship Design and Equipment (DE) to
develop relevant guidelines.
2.
Subsequently, the SLF Sub-Committee, at its forty-sixth session (8 to 12
September 2003), prepared draft SOLAS amendments to address the stability
issues on bulk carriers of less than 150 m in length, and at its forty-seventh
session (13 to 17 September 2004), prepared the Guidelines on the provision of
stability-related information for bulk carriers, for all new bulk carriers.
3.
The Maritime Safety Committee, at its eightieth session (11 to 20 May 2005),
following the recommendation of SLF 47, approved the Guidelines on the
provision of stability-related information for bulk carriers, as set out in the
annex.
4.
Member Governments are invited to bring the annexed Guidelines to the attention
of stability instrument manufacturers, related computer software developers,
mariners, dry cargo terminal operators and other parties involved in cargo
operations.
Annex.
GUIDELINES ON THE PROVISION OF STABILITY-RELATED INFORMATION FOR BULK CARRIERS
The
aim of this document is to provide detailed, comprehensive and user-friendly
guidance on provision of stability-related information and stability computing
software supporting for the safe operation of bulk carriers and, in particular,
those bulk carriers to which SOLAS regulation XII/11.3 applies.
Stability
data is a set of data resulting from ship design process. It covers stability
characteristics pertaining to a specific ship. Stability data is the base for
ship stability calculation in operation, especially stability assessment, by
means of hand made calculations or by stability instrument.
2.2.1
A stability instrument is an instrument, either analogue or digital, provided
for ships, by means of which all relevant stability information is provided and
all calculations or checks can be easily and quickly performed, as necessary,
to ensure compliance with the applicable stability requirements.
2.2.2
In this context, the stability instrument comprises the hardware and software.
3.1 Stability data and other
information
Stability
data should include the data and information outlined here under. 3.1.1 General
information:
.1 ship’s name;
.2 type of ship
(i.e. bulk carrier);
.3 name of
builders and new building number;
.4 date of build
(keel laying) or conversion;
.5 class
notation;
.6 nationality,
port of registry and IMO number;
.7 principal
dimensions (length, breadth and depth);
.8 type of load
line assigned (type A, B, B-60, etc);
.9 maximum mean
permissible draught corresponding to the summer freeboard assigned;
.10 maximum mean
permissible draught corresponding to the summer timber freeboard (if
appropriate);
.11 displacement
in salt water (at stated density) corresponding to .9 and .10 at the designed
(level) trim;
.12 maximum
permissible draught at the forward perpendicular for bow height considerations;
.13 the minimum
recommended draught at the forward perpendicular for any sailing condition;
.14 stability
limitations of the ship’s design, both for loading operation and, where
applicable, associated with undertaking ballast water exchange at sea; and
.15 lightship
particulars obtained from inclination test or lightship survey.
3.1.2
A scaled arrangement drawing showing clearly the use and distribution of the
various cargo compartments, tanks, stores as well as machinery and
accommodation spaces. Names of compartments used in the text of the document
should be clearly indicated.
3.1.3
A table of capacities with centres of volume (longitudinal, vertical and
transverse) for every compartment available for the carriage of cargo, fuel,
stores, feed water, domestic water and water ballast. Where applicable, such as
for cargo holds, tables or curves giving capacity and centre of volume as
functions of compartment depth or ullage should be included. When ullage is
used, the ullage reference point should be clearly stated. The reference planes
and the positive direction in all six degrees of freedom for centres of volume
should be the same as those used for any computer or other information provided
as an aid to the safe loading of the ship.
3.1.4
Free surface effect tables and/or curves for every tank and cargo hold that may
contain liquid, as a function of volume showing the effect on the stability of
the ship of liquids in partially filled tanks. These tables/curves should give
the free surface moments necessary to correct the initial metacentric height
and those to correct the righting lever values when the ship is inclined. In
the case of tanks containing liquids which may be consumed, discharged or
transferred to and from other compartments while the ship is at sea, including
anti-rolling tanks and/or heeling tanks, the maximum free surface moments which
may be developed should be given. When holds or deep tanks containing liquids
are maintained partially filled while the ship is at sea, the free surface
moments used may be based on the actual quantity of fluid contained.
3.1.5
Hydrostatic particulars for the ship at designed trim, in curve or tabulated
form, to a base of mean draught measured to the bottom of the keel over a range
covering the lightship and maximum draughts. When tabulated, these should
correspond to evenly-rounded units of draught at intervals appropriate to the
size of ship. The particulars should include:
.1 extreme
displacement in salt water at stated density;
.2 immersion
(displacement per unit interval of draught);
.3 moment to
change trim one unit;
.4 transverse
metacentre height above baseline;
.5 transverse
centre of buoyancy;
.6 vertical
centre of buoyancy;
.7 longitudinal
centre of floatation; and
.8 longitudinal
centre of buoyancy.
Position
of reference planes should be stated in the case of items specified in
paragraphs 3.1.5.4 to 3.1.5.8 and should be the same as the corresponding
reference planes for centres of gravity.
3.1.6
Details of load line, draught marks and deadweight particulars. A diagram
should be provided showing the load line marks including:
.1 position of
the deck line relative to the upper extreme of the ship’s depth;
.2 draught to
the summer load waterline;
.3 draught to
the summer timber load waterline (if appropriate);
.4 corresponding
freeboards, this or other diagram or tabular presentation should also give the
relationships between:
.5 mean draught;
.6 extreme
displacement;
.7 immersion
(displacement per unit interval of draught); and
.8 deadweight.
The
positions of the draught marks should be defined in relation to both the ship’s
perpendiculars and the longitudinal reference plane mentioned above.
3.1.7
Form stability particulars (Cross curves of stability). Data in the form of
curves or tables showing the relationship between form righting lever, angle of
heel and displacement at the designed trim over the full operational range of
displacement. Where the operating trim or form and arrangement of the ship are
such that a change in trim has an appreciable effect on righting arms,
additional form stability data should be included for a suitable range of trim.
The form stability information should be presented in a form that enables
righting arms to be readily determined to the nearest centimetre.
3.1.8
Set of stability criteria required by the Administration.
3.1.9
Limiting envelope curves resulting from intact stability and damage stability,
when appropriate. These curves should be clearly stated as being GM required
curves or KG maximum curves.
3.1.10
Auxiliary data which are necessary to prove compliance with the relevant
stability criteria and, when appropriate, icing data.
3.1.11
Master’s instructions should precisely and unambiguously detail how the information
provided in the stability data and elsewhere is to be used to obtain the
draught, trim and stability characteristics of a new loading condition and
determine whether that condition fulfils the relevant stability criteria.
3.1.12
Loading conditions
3.1.12.1
The loading conditions covered by the stability data should include:
.1 lightship;
.2 docking;
.3 fully loaded
departure, with cargo homogeneously distributed throughout all cargo spaces and
with full stores and fuel;
.4 fully loaded
arrival, with cargo homogeneously distributed throughout all cargo spaces and
with 10% stores and fuel remaining;
.5 ballast
departure, without cargo but with full stores and fuel;
.6 ballast
arrival, without cargo but with 10% stores and fuel remaining;
.7 other
departure and arrival conditions typical of the ship’s intended service, such
as alternate hold loading, ore loading, deep ballast, etc. as applicable; and
.8 where
appropriate, other conditions used for ballast water exchange.
3.1.12.2
For each loading condition, the following should be shown:
.1 a sketch of
the ship indicating, pictorially, the main items of deadweight included in the
displacement;
.2 a table
showing the lightship particulars, the distribution of all components of the
deadweight, the positions of their centres relative to the defined reference
planes, corresponding static moments and a summation giving the result which
should show the full displacement mass and the position of its centre;
.3 a table
listing the free surface effects of liquids in all compartments which may be
partially filled;
.4 a diagram
showing the curve of righting levers (GZ), corrected for free surface effects,
plotted against angle of inclination. The scales used should be the same for
each loading condition; and
.5 a summary of
the condition giving:
.5.1
displacement and related sea water density;
.5.2
corresponding draught at longitudinal centre of