The paper discusses a methodological approach applicable during the final stage of new ships" design to foresee their in service availability or during operation to improve maintenance policies and fleet management. The method applies Monte Carlo simulation to a reliability model of the ship or her subsystems, based on reliability block diagrams and maintenance plans. A case study showing the applicability of the approach to fast ships is presented and the results obtained are discussed.
Current market and passengers" demands are calling for higher performance standards for Fast Ferries than in the past years [Capizzi et al. 1997]. It follows that special attention should be paid to ship availability, warranted by an optimised combination of maintenance activities and systems" reliability. Maintenance activities, which are usually accomplished out of service, need an efficient organisation and schedule, in order to maintain the ship at high operative levels. Moreover, good quality items contribute positively to achieve high ship reliability during operation. In order to be sure of providing a good service, especially for the routes where competitor companies operate, the ship operators need to know, since the beginning of the service of a new High Speed Craft, the probability of mission success with a good passengers" comfort. This means that ship operators should receive high benefices from the outcomes of provisional studies of ship availability. These studies support them to the optimisation of the maintenance and ship operability. Moreover, they provide them with a quantitative assessment of ship availability, i.e. the probability that the vessel accomplish its mission with respect to the total time it is asked to operate. A method for the provisional assessment of ship availability, addressed both to ship builders and ship operators [Vivalda et al. 1998] is presented.
