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Bulk
Carrier Safety
Interpretations
of SOLAS Chapter XII
Pursuant
to several tasks contained in the 1997 SOLAS Conference resolutions,
the MSC issued resolution MSC.79(70) which urges Member States to
apply the following clarifications concerning the application of
SOLAS Chapter XII to bulk carriers. 4.18
Length limit - the lower length limit of 150m, to which SOLAS
Chapter XII applies, should not be lowered unless indicated otherwise
by a formal safety assessment scheduled to be carried out in the
next 18 months. The MSC noted IACS position that bulk carriers less
than 150m would meet the strength requirements, but that considerable
difficulty can be expected in complying with flooding stability
requirements.
Bulk
carrier definition - The resolution reiterates the definition
of bulk carrier as per SOLAS Conference Resolution 6 and thus removes
ambiguities in the SOLAS Chapter XII definition of bulk carrier,
which is the same as the ISM Code definition as per SOLAS regulation
IX/1.6. To determine if a ship is a bulk carrier under the ISM Code
and the safety requirements for bulk carriers under SOLAS Chapter
XII, a "bulk carrier" means a ship constructed with a single deck,
top side tanks and hopper side tanks in cargo spaces and intended
to primarily carry dry cargo in bulk; an ore carrier; or a combination
carrier. Also, recognizing that the accepted legal format of most
SOLAS certificates do not indicate the specific type of ship, the
resolution indicates that the certificated identification of ship
type is as it appears on the ISM Code Safety Management Certificate.
Double sides - Recognizing the reduced probability of water
ingress due to shell cracks, corrosion and low energy impact damage
when cargo holds are protected from the sea by double sides, the
MSC is endeavoring to set a minimum distance in order for a double
sided bulk carrier to be exempt from the single side skin requirements
of SOLAS Chapter XII. However, this session of MSC could not agree
on the minimum distance separating the cargo hold from the side
shell. One proposal that was discussed proposed a distance of 760mm
for existing bulk carriers built before 1 July 1999 and 1.0m for
bulk carriers built after that date. This matter is scheduled to
be finalized at MSC 71 in May 1999. In order to preserve the reduced
risk of flooding afforded by double sides, the minimum distance
should allow for effective access and inspection of the side structure.
Exemptions
- Bulk carriers, arranged with an insufficient number of` bulkheads
necessary to meet the stability and structural survivability requirements
under the provisions of regulations XII/4 and 6, may be exempted
from those requirements. However, the resolution clarifies that
eligibility for this exemption becomes void if the ship has been
modified thereby reducing the number of transverse watertight bulkheads.
Cargo
density - It was agreed that on/after 1 July 1999, the declaration
of solid bulk cargo density, when between 1250 to 1780 kg/m3, must
be verified by an accredited testing organization. This would apply
to such cargoes being carried by existing bulk carriers built before
1 July 1999, unless the ship fully complies with SOLAS Chapter XII
for bulk carriers carrying cargoes with densities of 1780 kg/m3
and above. Also, it was agreed in principle - subject to discussion
at MSC 71 in May 1999 - that bulk carriers, carrying break bulk
cargoes with stowage factors of 0.56 m3/ton or less, should be subject
to the provisions of SOLAS Chapter XII.
Seakeeping Assessment
The
United Kingdom and Greece presented the results of their qualitative
and quantitative analyses and computer simulations carried out to
determine the sensitivity of the seakeeping performance of bulk
carriers in extreme seastates. The U.K. research presents relationships
between the susceptibility of deck wetness and deck loads for varying
physical aspects, focsle configuration and magnitude of bow height,
shape and flare for the 160,000 dwt OBO "Derbyshire".
Although
having a different objective than the U.K. research, the Greek research
focused on the effects of operational measures such as speed, heading
and weather routeing. The research aimed to establish optimal weather
routeing (speed and heading) by identifying minimum possible wave
induced motions, loads and deck wetness.
By
carrying out a parametric analysis for varying headings, speed and
wave period and spectral distributions, predictions and trends similar
to the U.K.'s work were concluded for 4 different sizes of typical
bulk carriers, albeit for a different purpose.
Recognizing
the areas where there were corroborating results and considering
the impact of operational parameters on seakeeping performance,
the MSC agreed that further work in evaluating risks associated
with bulk carriers should be performed and that the physical aspects
(bow height) and operational aspects (speed and heading) should
be jointly considered.
IACS
presented the results of its analysis which was used to develop
an IACS Unified Requirement on the design loads for the fore end
hatch covers. The IACS design loads, applicable to ships built after
1 July 1998, are significantly larger than the loads required by
the 1966 Load Line Convention as illustrated below.
After
reviewing and discussing the above analyses, the MSC instructed
its SLF Sub-Committee to further consider the adequacy of the current
regulations relative to:
- hatch cover/coaming strength;
- bow height; - reserve buoyancy;
- mitigation of forward structural
loads; and
- protection of crew access
to the bow.
Future
sessions of the MSC will consider for new and existing bulk carriers,
after completion of the Formal Safety Assessment (FSA) and the IACS
hazard identification study (see below), the following issues:
- loss of steering and the degree
of redundancy considering casualty statistics;
- tank sounding/bilge alarms
and emergency pumping;
- additional training measures,
particularly for operation in extreme weather conditions; and
- free-fall life boat capabilities;
FSA
and HAZID Studies
The
MSC endorsed the U.K.'s proposal for a collaborative formal safety
assessment study of bulk carriers by Administrations and industry
organizations outside the confines of IMO. In light of concerns
expressed relative to the broad scope, manner of conduct and prioritization
of safety issues of the proposed study, the MSC recommended that
the FSA study consider human element aspects as per IMO's draft
guidelines and be conducted in accordance with IMO's FSA Interim
Guidelines.
IACS
is undertaking a hazard identification study on the watertight integrity
of the fore end structure of bulk carriers. Scheduled to be completed
by May 1999 for MSC 71, the study will evaluate the potential hazards,
their causes and consequences. Aspects to be addressed will be the
design and operation of closures and systems serving cargo holds
and tanks in the fore end of bulk carriers including hatchcovers,
airpipes, ventilation trunks, bilge alarms and sounding and emergency
pumping systems. Influence of the human element on the effectiveness
of the above systems and closures will also be considered.
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