| Abstract | In September 1994 the RO-RO Ferry Estonia sank of the coast of Finland, with the tragic loss of over 900 passengers and crew. The preliminary results of the official inquiry showed that the ferry sank because the bow visor was knocked loose by the force of the waves. This allowed the car deck to flood, resulting in the capsize and sinking of the ship. During the course of a project to modernize an existing ferry, the Institute for Marine Dynamics and Marine Atlantic carried out a series of model experiments to determine the wave induced loads on the bow visor. The model was rested for a range of speeds, significant wave heights and directions, to determine the maximum load likely to occur in operating conditions. Measured loads were correlated with measure motions and these relationships together with strip theory calculations were used to determine if the data set could be expanded beyond the region where physical experiments were carried out. This paper presents the results of the model experiments, giving measured values for ship motions and bow visor loads, together with the predictions from strip theory. It also compares the measure loads with those predicted from the International Association of Classification Societies (IACS). The results show that the IACS predictions compare well with the measured data for vertical and longitudinal loads in waves up to 6 metres significant height. They also show the the IACS formula over-predicts lateral loads for the wave conditions and ship speeds tested. |
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