Feature 2 | Damage Stability
IMO takes action on damage stability
Damage stability in chemical tankers came under scrutiny again at the
International Maritime Organization (IMO) during the last week of January
2010, the UK authorities were at the forefront of the debate.
F
ollowing discussions at the “The UK delegation will lead the the tanker loaded using in tact stability
International Maritime correspondence group established to guidelines would automatically meet the
Organization’s (IMO) develop the guidelines and we hope that damage stability rules as well. The MCA
sub-committee SLF 52 (Stability, Load Line we can reach a consensus before the SLF53 rejected this view and has sought to enforce
and on Fishing Vessels) agreement was meeting [the next sub-committee meeting regulations more rigorously.
reached by the delegates that guidelines due to take place in January2011], which However, some of the parties present
should be produced to help owners, will then decide on the final form of the were not fully behind this decision at the
operators and inspectors to ensure that guidelines,” said Mr Coley. sub-committee meeting with some owners
chemical tankers can survive an accident, concerned that ships could be delayed in port
should it occur, when they leave port. and that these delays would mean they incur
A working group was established to
determine what will be contained in these
“The UK delegation
extra expenses. The International Parcel
Tankers Association (IPTA) believes that the
guidelines which will be divided into the
will lead the
MCA’s survey sample, of 70 ships, was far too
design and application of damage stability small to make an informed judgement. Even
information as defined by naval architects,
correspondence
so IPTA confirmed in a written statement
and operational guidelines will help
group established
that: “IPTA will participate in the ongoing
masters, owners, surveyors and inspectors discussions on this issue, and welcomes the
ensure that a vessel meets damage stability
to develop the
fact that the Sub-Committee agreed that in
regulations before the vessel leaves a port
and after loading.
guidelines and we
order to be able to develop Guidelines for
onboard verification of damage stability
“It will essentially tell a master what is
hope that we can
where the ship is in a non-approved
expected of him,” explained Paul Coley, condition, it is important, firstly, to establish
assistant director seafarers and ships at the reach a consensus what constitutes an approved condition, as
UK’s Maritime and Coastguard Agency.
The guidelines will supplement the
before the SLF53 ”
well as clarifying what can be considered
a significant deviation from an approved
regulations that are already in place, but are condition.”
not necessarily enforced, because many in The last point was also picked as a key
the industry are unaware that the damage In addition an inspection campaign is issue, before the meeting, by ClassNK which
stability of chemical tankers can vary planned for later this year and states and told The Naval Architect that the situation
significantly depending on the number administrations will be asked to “consider regarding older chemical tankers may not
of tanks that have cargo, how full those this year’s meeting when their officers carry be the same as for more modern ships and
tanks are and the specific gravity of those out inspections,” said Mr Coley. this could mean that different calculations
cargoes. Backed by co-sponsors from Germany, could be made for the same vessels.
One source said: “there is no need Denmark, Sweden and Norway the UK ClassNK explained: “One of the reasons
to change the regulations, SOLAS and delegation took research evidence collated for this is the difficulty in obtaining the
MARPOL are fully understood, the main by the MCA to the IMO sub-committee necessary information to calculate damage
difficulty is that the loading book is to reinforce its view that many chemical stability and operate onboard computers
produced at the design stage and owners tanker operators were failing to meet for aged vessels. Such information might
think that covers all operations, but it damage stability regulations. The MCA include, for example, lines and offset
doesn’t cover every permutation that a ship surveyed tankers calling at UK ports (hull form data) including inner-hull
could load during its lifetime.” and found that around 50% of chemical information, due to the intellectual property
This is particularly difficult for chemical and product tankers were either not in rights of the shipyard or bankruptcy of the
tankers, as opposed to crude carriers and compliance or were unaware whether the shipyard. Even when such information
gas tankers which were also considered at vessel had met the damage stability rules or is available, the original damage stability
the January meeting, because of the wide not before leaving port. booklet has usually been prepared using
variation in specific gravity for the cargoes Additionally the MCA’s research found an older programme and the calculation
that a chemical tanker might carry. that many operators believed that if results would likely differ from results
50 The Naval Architect February 2010
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