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Sinking of Estonia, an industry failure? In-depth | DAMAGE STABILITY


Have the lessons of the Estonia disaster, 16 years ago this month, been learnt? Controversial naval architect Anders Björkman believes that the industry has shirked its responsibility by failing to recognise some obvious clues, and therefore remedies, to the causes of the disaster.


lives, the lessons that should be derived from this catastrophe are still contested by many in the industry who feel that the official version of events does not go far enough in explaining how the ship was lost. Essentially the accident involving


S


Estonia occurred at between midnight and 2am on the morning of the 28 September 1994 as the ship was making the crossing from Tallinn to Stockholm. A storm was blowing, around 7-8 on the


Beaufort scale with wave height at around 3-4m which was described in some reports as a normal autumn storm for the region. Official reports suggest that a failure of the bow visor caused the flooding of the car decks and the free surface effect capsized and sank the vessel within a very short period of time, less than one hour. Many challenges to the official version


have been made and some views are seen as unlikely while many others are open to interpretation. Anders Björkman’s view as a naval architect gives an insight into what could be the causes of the continued and persistent speculation around the loss of Estonia. In Mr Björkman’s view the vessel was


unseaworthy before it set sail because it contravened a number of regulations that should have seen the vessel prevented from operating. However, the initial cause of the


accident and the reason for the first sudden listing, more than 30deg at 01.02hrs according to a majority of the survivors, must have been a heavy leak below the waterline with a failure by the crew to take proper action, “except starting the bilge pumps”. Te leakage had apparently started at 00.50-00.55hrs, according to Mr Björkman’s findings. Leaking sea water through its hull the


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ixteen years aſter the capsize and sinking of Estonia in the Baltic in heavy weather, with the loss of 852


Figure. 1 Passenger Carl Övberg on deck 2 sees water flooding up from compartment on deck 1 below. The red paths show alternative escape routes of crew member Henrik Sillaste who did repairs in the sewage room below Carl Övberg’s cabin at time of heeling/ accident.


water was allowed to spread through open watertight doors on the tank top, so that the initial stability, GoM, was reduced to nil due to the free water surfaces inside the ship hull at 01.02 hrs (three or four compartments filled with about 600 tonnes of water). Alternatively - if the leak was a fracture


in the shell plate just above the bilge strake, the fracture could have developed forward and aſt so that the leak and water inflow spread into several dry compartments, including the starboard heeling tank. Ten - at 01.02 hrs - the ship heeled


suddenly, more than 30 degrees, but stabilised at 15 degrees heel as expected (the new equilibrium due to the water on the tank top) during many minutes, when several hundreds of crew and passengers


were evacuated to open decks 7 and 8. Te ship, then rolling severely with a


list of around 15 degrees due to reduced GoM, enabled passengers to get out as it was possible to walk on the decks when the ship rolled to port and the angle of list was close to 0 degrees. When it rolled to starboard the list was more than 30-40 degrees and you could not get out until the ship rolled back to port. As the ship rolled more water came in


below the waterline, the ship listed more, but it did not capsize (it was stable, but with a list) and then it sank on the stern hitting bottom at 01.33 hrs. The clock on the bridge stopped at 01.35 hrs, thus aſter that time the ship could not move further. Estonia was plotted on radar and seen


The Naval Architect September 2010


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