CRUISESHIP TECHNOLOGY Guidance towards design alternatives
CRUISESHIP designers can look forward to a newly flexible regulatory regime when it comes to meeting safety requirements set out by the International Maritime Organization but, as ever with developing guidelines, certain fine details remain to be seen.
D
ECEMBER’S 82nd session of the Maritime Safety Committee meeting in Istanbul
concluded with significant revisions in passenger ship safety standards. The package of amendments to SOLAS adopted
at the session were the result of a comprehensive review of passenger ship safety initiated in 2000 with the aim of assessing whether existing regulations were adequate, in particular for the large passenger ships now being built. They envisage a mechanism for the approval
of alternative ship designs and arrangements that deviate from the prescriptive requirements of SOLAS chapters II-I and III. An IMO statement said that the work had based
its guiding philosophy on the dual premise that the regulatory framework should place more emphasis on the prevention of a casualty from occurring in the first place and that future passenger ships should be designed for improved survivability so that, in the event of a casualty, persons could stay safely onboard as the ship proceeded to port. Although these are guidelines only, they serve
to outline a new methodology for the engineering analysis required by SOLAS regulations II-1/55 and III/38, applying to a specific engineering or life-saving system, design or arrangements for which approval of an alternative design deviating from the prescriptive requirements of SOLAS chapters II-1 and III is sought. The amendments require the consideration of
new concepts, such as criteria for the casualty threshold (the amount of damage a ship is able to withstand, according to the design basis, and still safely return to port). They have also been framed to provide flexibility,
with a view to allowing ship designers to meet any safety challenges the future may bring. The amendments, which are expected to enter into force on July 1, 2010, include:
• alternative design and arrangements for a range of measures, including shipboard structures and systems based on novel or unique designs, as well as traditional shipboard structures and systems that are installed in alternative arrangements or configurations.
•
safe areas and the essential systems to be maintained while a ship proceeds to port after a casualty, which will require redundancy of propulsion and other essential systems;
• on-board safety centres, from where safety systems can be controlled, operated and monitored;
•
fixed fire detection and alarm systems, including requirements for fire detectors and manually operated call points to be capable of being remotely and individually identified;
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Freedom of the Seas – construction of ever larger cruiseships prompted administrations to undertake a full review of the guidelines governing their design in order to meet safety requirements. Results flowed from December’s MSC 82.
• •
fire prevention, including amendments aimed at enhancing the fire safety of atriums, the means of escape in case of fire and ventilation systems; and
time for orderly evacuation and abandonment, including requirements for the essential systems that must remain operational in case any one main vertical zone is unserviceable due to fire.
Furthermore, the MSC adopted amendments
to SOLAS chapter II-2 and to the International Code for Fire Safety Systems (FSS Code) to strengthen the fire protection arrangements in relation to cabin balconies on passenger vessels. These particular amendments were developed specifically in response to the fire aboard the cruise ship Star Princess, while on passage between Grand Cayman and Montego Bay, Jamaica, in March of last year. A fire began on an external balcony and spread over several decks. They are aimed at ensuring that existing regulations 4.4 (Primary deck coverings), 5.3.1.2 (Ceilings and linings), 5.3.2 (Use of combustible materials) and 6 (Smoke generation potential and toxicity) are also applied to cabin balconies on new passenger ships. In view of the urgency that such amendments
are required, they are expected to enter into force on 1 July 2008. However, it is in the over-arching shift
in the approach to ship design that the true significance of the new guidelines lies. They envisage all interested parties, including the Flag State, owners, operators, designers and classification societies being
in continuous communication from the outset over any specific proposal to use them for alternative design solutions. ‘This approach usually requires significantly more time in calculation and documentation than a typical regulatory prescribed design because of increased engineering rigour,’ according to an IMO circular. Not all proposed amendments to SOLAS
were agreed at MSC. For example, amendments regarding stability were not accepted and were sent back to the Sub- Committee on Stability and Load Lines and on Fishing Vessels Safety for further debate and refinement. However, Capt Ted Thompson, senior vice
president for Cruise Lines International Association, was in no doubt as to the profound nature of the change. ‘Future passenger ships will be built to the newly adopted probabilistic damage stability regulations that were developed over a time frame of about 12 years,’ he said. ‘Additionally, IMO recently adopted regulations requiring new passenger ships to survive and return to port while providing essential life services after a fire that disables an entire main vertical zone (providing for separation, redundancy and protections or vital systems passing through that zone) and to provide similar redundancy, separation and protections of systems to return to port.’ Survivability meant the ability to return
to port under own power while providing essential life services after disabling any one main vertical fire zone or flooding of any one watertight compartment, he said.
THE NAVAL ARCHITECT FEBRUARY 2007
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