The reliability of the main engine must be extremely high in order to ensure the safe navigation of ships. This paper describes the construction of monitoring system capable of grasping the condition of the engine by using vibration signal of a diesel engine. The vibration was measured by sensors on cylinder jaket walls.
The data of vibration were recorded on both normal and abnormal engine conditions. The following two kinds of conditions were used as an abnormal engine condition: running with fuel oil cut and the use of stopped-up fuel injection nozzle. Author executed visual judgment by means of the spectrum of the vibration in three-dimensional mannar and analyzed statistically as one method to estimate the condition of engine by the information from the vibration. It was found that one abnormal cylinder affected on vibration of other normal cylinders. Author succeeded to recognize abnormal engine condition correctly by mean of their information.