Formal safety assessment of fishing vessels: risk and maintenance modelling

Comparisons of the safety record of the fishing industry with other industrial sectors indicate that it continues to be the most dangerous occupation by a significant margin. Satety data from fishing vessels are scarce and often accompanied with a high degree of uncertainty. For this reason the use of conventional probabilistic risk assessment may not be well suited. This paper proposes two novel approaches for risk and maintenance modelling of fishing vessels. An approach using fuzzy set theory (FST) is developed to model the occurrence likelihood and consequences for the identified hazards on a fishing vessel. As the time between maintenance opportunities of a fishing vessel can vary considerably, it allows for failures on the machinery to propagate and lead to a catastrophic breakdown. A model using delay time analysis (DTA) is proposed to ascertain the optimal inspection period for fishing vessel equipment depending on the criteria selected. The two criteria modelled are down time and cost. As both these criteria may not be satisfied simultaneously, a best compromise is proposed. Test data from an ocean going trawler are used to demonstrate the two proposed approaches and the results obtained are discussed in detail.