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In-depth | DAMAGE STABILITY FEATURE THEME Flood prediction research finalised


Te EU-funded research project FLOODSTAND, the Integrated Flooding Control and Standard for Stability and Crisis Management, was finalised in February, aſter three years of research work, writes Henrik Segercrantz.


7th Framework Programme, focused on cruise ships and ro-ro-passenger vessels. Te ambitious project had two main objectives: to increase the reliability of


T . And to establish a


he €4 million (US$5.2 million) FLOODSTAND project, part of the European Commission’s (EC)


flooding


simulation tools in design and onboard use by establishing modelling principles and uncertainty bounds1


method for instantaneous classification of the severity of ship flooding casualty, with the following key objectives: Two cruise ship designs were of different


sizes, which were also designed according to SOLAS 2009 by STX Finland and Meyer Werft, were developed and used for the damage calculations, simulations and tests. Te ro-ro-passenger vessel design used was that of Estonia. Te effect on the progress of flooding of ‘non watertight’ doors and other constructions were studied. Te results are used in flooding simulations, which are used for establishing reliable damage stability calculations, and also to assess the stability and flooding extent onboard a damaged ship


for decision support. Te work included, for example, assessment of the real flow through the air ventilation pipes from tanks, and tests and computational analysis to assess the water flow through cross-flooding ducts and through refrigeration areas. Te doors and structures were tested in full scale by CTO in Poland. Model tests were done by Aalto University in Finland, SSPA in Sweden, and by MARIN in Te Netherlands (where tests can be made under vacuum, to provide a correct Froude scale effect).


Brief results2 This work resulted in more precise input data for analysing water progression and the time it takes. Rough guidelines for modelling leakage and collapse of various A- and B-class doors, etc, for flooding simulations could be developed. Some improvements in the design of the watertight subdivision of cruise ships can now be made to enhance safety. Although, not providing any dramatic results with a significant influence on the global design of cruise ships, it showed that the explanatory notes of IMO’s SOLAS could be


Full scale testing of the rigidity of fire doors in case of flooding was conducted by CTO in Gdansk, Poland. (Photo: CTO)


improved. It was, for example found that the locking devices in some cases were the first to break, and that A-class fire doors collapse at a water column of some 2.5m, a very likely scenario under the bulkhead deck. Based on this, designers can more freely place these fire boundaries in, for example, the engine room reducing the risk of fire propagation without affecting the subdivision index negatively. On the other hand, it was concluded that adding fire doors in the service corridor above the bulkhead deck is advantageous. It was found that the regression equation on flooding progression through cross-ducts as currently recommended in IMO’s Resolution MSC.245(83) gives about +30% higher values for the discharge coefficient, which may cause a significant under-estimation of the factual cross-flooding time. The flooding phenomena can now be


better modelled in the calculations carried out by the designers. Te guidelines arrived at by the FLOODSTAND project have been made available to IMO to improve the SOLAS convention and its explanatory notes. Te second aim of FLOODSTAND was


to develop a standard for decision making on abandonment during flooding crises situations and a standard approach for a comprehensive measure of damaged ship stability addressing the flooding risk. Te project management described: “the key issue is the availability and reliability of the information needed for making a reasonable decision. A decision criterion, or a decision process must be able to robustly accommodate these problems and inherent uncertainties.” Much work was directed at looking into the


time it takes for a ship to capsize or sink aſter damage through analytical and numerical methods, as well as through flooding model tests. Extensive tests with the studied damaged ro-ro-passenger vessel clearly showed that in many feasible flooding situations the time from damage to capsize is only several minutes, precluding an orderly evacuation. FLOODSTAND provided important data relating to SOLAS regulation II-1/22.4


20 The Naval Architect March 2012


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