Circular Letter MSC/Circ.998
IACS UNIFIED INTERPRETATION REGARDING TIMBER DECK CARGO IN THE CONTEXT OF
DAMAGE STABILITY REQUIREMENTS
(adopted
on 4 June 2001)
1.
The Maritime Safety Committee, at its seventy-fourth session (30 May to 8 June
2001), having considered a recommendation made by the Sub-Committee on
Stability and Load Lines and on Fishing Vessels Safety (SLF) at its forty-third
session, agreed that IACS Unified Interpretation SC161 - Timber Deck Cargo in
the Context of Damage Stability Requirements, should be disseminated among
Administrations in order to ensure uniformity in the calculation procedure for
the allowance of buoyancy in this context.
2.
Member Governments are recommended to apply the attached IACS Unified
Interpretation when implementing SOLAS regulation II-1/25-8.1, and at the same
time, are invited to bring said Unified Interpretation to the attention of all
parties concerned.
ANNEX.
IACS UNIFIED INTERPRETATION REGARDING TIMBER DECK CARGO IN THE CONTEXT OF
DAMAGE STABILITY REQUIREMENTS
SC161 (May 2000) - Timber deck cargo in the
context of damage stability requirements (Chapter II-1, Regulation 25-8.1)
SOLAS
Regulation II-1/25-8.1 reads:
1.
The master of the ship shall be supplied with such reliable information as is
necessary to enable him by rapid and simple means to obtain accurate guidance
as to the stability of the ship under varying conditions of service. The
information shall include:
.1 a curve of minimum
operational metacentric height (GM) versus draught which assures compliance
with the relevant intact stability requirements and the requirements of
regulations 25-1 to 25-6 alternatively a corresponding curve of the maximum
allowable vertical centre of gravity (KG)versus draught, or with the equivalents
of either of these curves;
.2 instructions concerning
the operation of cross-flooding arrangements; and
.3 all other data and aids
which might be necessary to maintain stability after damage.
The
provisions given hereunder apply to ships that are subject to SOLAS, Chapter
II-1, Part B-1 subdivision and damage stability calculations and engaged in
carrying timber deck cargoes. The buoyancy of the timber deck cargo can
optionally be taken into account in the damage stability calculations, subject
to the provisions that have been set forth in this document.
They
shall comply with the requirements of the Code of Safe Practice for Ships
Carrying TIMBER Deck Cargoes, 1991, and Ships that are provided with
and make use of their timber load line shall also comply with the requirements
of regulations 41 to 45 of the Load Line Convention.
The
following definitions apply for the purposes of this interpretation:
- timber means sawn wood or
lumber, cants, logs, poles, pulpwood and all other types of timber in loose or
packaged forms. The term does not include wood pulp or similar cargo;
- timber deck cargo means a
cargo of timber earned on an uncovered part of a freeboard or superstructure
deck. The term does not include wood pulp or similar cargo;
- timber load line means a
special load line assigned to ships complying with certain conditions related
to their construction set out in the Load Line Convention and used when the
cargo complies with the stowage and securing conditions of the Code of Safe
Practice for Ships Carrying Timber Deck Cargoes, 1991 (Resolution A.715(17));
- deepest timber subdivision
load line is the subdivision load line which corresponds to the timber summer
draught to be assigned to the ship;
- respective partial load
line is the light ship draught plus 60% of the difference between the light
ship draught and the deepest timber subdivision load line.
1.
The stowage of timber deck cargoes shall comply with the provisions of Chapter
3 of the Code of Safe Practice for Ships Carrying Timber Deck Cargoes, 1991
(resolution A.715(17)).
2.
The ship shall be supplied with comprehensive stability information which takes
into account timber deck cargo. Such information shall enable the master,
rapidly and simply, to obtain accurate guidance as to the stability of the ship
under varying conditions of service, and as required in SOLAS Regulation
II-1/25-8 it shall include, among other damage stability related issues, a
curve of minimum operating metacentric height (GM) versus' draught which covers
the requirements of SOLAS Regulation II-1/25-8.1.1.
3.
The height and extent of he timber deck cargo shall be in accordance with
Chapter 3.2 of the Code of Safe Practice for Ships Carrying Timber Deck
Cargoes, 1991, and shall be at least stowed to the standard height of one
superstructure, if considered buoyant in the context of the subdivision and
damage stability calculations.
4.
Account may be taken of the buoyancy of the timber deck cargo, assuming that
such cargo has a permeability of 25% of the volume occupied by the cargo,
however, the buoyancy of only one standard superstructure height of timber deck
cargo may be considered.
5.
Unless instructed otherwise by the Administration, the stability information for
ships with timber deck cargoes may be supplemented by a second curve of
limiting GM (or KG) covering the then permissible draught range as specified
below. Thus when accepting two stability limiting curves one curve shall be
applicable when carrying timber deck cargo and a second curve for any other
loading condition.
6.
The above described provision of two curves are to be developed as described in
SOLAS Regulation II-1/25-8.3, if they have been determined from considerations
related to the subdivision index, based on the following:
6.1 for any loading
condition other than timber deck cargo the limiting GM with the draughts as
described in SOLAS Regulation II-I/25-8.3, and
6.2 for timber deck cargo
the limiting GM shall be varied