The semi-Markov model of the process of appearance of sea-going ship propupsion system ability and inability states in application to determining the reliablity of these systems

The article presents possible application of the theory of semi-Markov processes in creating the eight-state model of the process of appearance of the propulsion systems ability and inability states on sea-going vessels performing transportation tasks in a relatively long operating time t (t → ∞). The model has been proved to be able to be successfully used for determining the reliability of the abovementioned systems. The probability of faultless operation in time t was assumed the measure of system reliability. Operating situations of sea-going vessels were characterised, with special attention being paid to the fact that the loads of propulsion system components of these vessels are of random nature. These loads lead to damages which for this reason were also considered random events. It was also assumed that the damages provoke the appearance of states of inability of particular ship propulsion system components which means that these states are random events as well. The states of ability of a given ship propulsion system have been assumed to exist when all components of this system are in the state of ability. In case when at least one component is in the state of inability, the entire system is in the state of inability. Conditions were formulated for the reliability model of an arbitrary system to be able to be worked out in the form of the semi-Markov process. The need for the use of technical diagnostics in reliability examination of sea-going ship propulsion systems was indicated. In conclusions, certain qualities of the article were highlighted which are, in author’s opinion, of highest importance in reliability examination of sea-going ship propulsion systems.