運航障害を生じた事故の分析

概要

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This paper discusses a reliability analysis on the casualties occurred by machinery failures in ship operation. The approach was to conduct a data analysis of failures on marine equipments to evaluate the difficulty of ship operation by the occurrence rate and the logistic delay time due to troubles. The total number of ships to be investigated was 1029 (vessel × year) and the observation period of investigation was twelve years.<BR>The main findings of the study are as follows:<BR>a. Casualties were remarkably increasing in number from in 1970 and showed a peak value in 1972. The occurrence rate of casualty in 1970s was almost twice of that in 1960s. However, the adoption of reduced ship speed operation after oil crisis have made a result in lower failure rate and delay time.<BR>b. The preponderance of the casualties was connected with failures of main propulsive machineries especially main diesel engines. The cause of diesel engine failures was originated from the tendency of high power rate per unit volume of engines.<BR>c. From the statistics at present time, 54% of detection was done by the senses of human being and 46% of detection was done by the mechanical means such as temperature, pressure and level sensor, to find out an abnormal state of a plant that leads to ship stop casualty. And only 11% of decision making was done by mechanical means to judge engine stop operation.