2019 Volume 141 Pages 1-8
In this study, it is focused on an evaluation of speed loss from the viewpoint of the operation of appropriate main engine. Our final goal is that to be classification of the nominal speed loss due to added resistance caused by wind and waves and the deliberate speed loss by the captain order. As the first step, a time varying autoregressive modeling procedure is applied in order to analyze a time series of main engine rotational speed. As to an evaluation an instantaneous spectrum was used. The time series data measured in cargo carrier was used for the analysis. As a result, it is confirmed that against the change of ship speed, the instantaneous spectrum of the main engine rotational speed is changed clearly. Therefore, it may be possible that the cause of the speed loss can be classified by the instantaneous spectrum.