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Feature 2 | CHEMICAL AND PRODUCT TANKERS


MCA ready to take tanker damage stability evidence to IMO


January’s meeting at the International Maritime Organization (IMO) to discuss chemical and product tanker damage stability is expected to present some tough negotiations, but to resolve the issue with a workable compromise.


Maritime Organization (IMO) is expected to reach its climax. The Maritime and Coastguard Agency (MCA) believe that the battle is essentially environmental concerns over commerce while the owners associations say that it is a question of common sense rather than unnecessary regulation. Ships are designed to withstand a


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certain amount of damage without the danger of the vessel being totally lost. But, accidents do happen and most vessels must be prepared to survive with at least some damage, particularly chemical and product tankers says the MCA. Damage stability physics in chemical


and product tankers is different to most other dry cargo and passenger ships according to the MCA and it is looking to ensure compliance through the IMO. Due to the large number of tanks


and the different chemicals carried that can have differing specific gravity the damage stability of a chemical tanker can vary from voyage to voyage as the centre of gravity shifts with the loading of the vessel. Whereas damage stability in dry cargo or passengers ship will remain more or less predictable from one voyage to the next. Consequently, the loading conditions


verified for damage stability compliance at build for a chemical tanker may not include the worst operational condition that occurs in service. Damage stability for dry cargo and passenger ships is assessed differently, on the worst possible case of damage, which is readily predictable and ensures a


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n January the debate over the enforcement of damage stability regulations at the International


The IMO regulation governing damage stability in ships.


Typical cargo distributions, for a vessel departing from port. The table shows the vessel is not at its marks at SG0.63 or SG0.74.


margin over the minimum statutory criteria as loadings vary from one voyage to the next. In an effort to determine how


widespread the failure to meet damage stability regulations is the MCA is coordinating a survey of vessels calling at some European ports. After inspecting more than 70 ships the MCA found that around 45% of chemical


and product tankers were either not in compliance or were unaware whether the vessel had met the damage stability rules or not before leaving port. Furthermore, many operators


believed that if the vessel was loaded using the loading computers for intact stability, that this would be sufficient for the vessel to meet damage stability rules. The MCA, however, says this is


The Naval Architect November 2009


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