Uncertainty analysis for measurement of added resistance in short regular waves: Its application and evaluation

Since added resistance in waves is a key parameter for prediction of ship performance in actual seas, it should be measured with sufficient accuracy. In general, the measurand obtained in a model test contains unavoidable error, which results from the complexity of the measurement procedure of such tests. Therefore, uncertainty which can quantify this error should be clarified for achievement of accurate measurement. The authors conducted repeat tests both for resistance in calm water and for added resistance in short regular waves to assess their uncertainty in three facilities in the National Maritime Research Institute, Japan (NMRI). The tests were conducted according to the procedure published by the International Organization for Standardization. This paper reports the results of the uncertainty analysis for resistance in calm water and added resistance in short regular waves and the comparison among the three facilities, which revealed that the predominant error component is different among the facilities. Furthermore, the authors calculated the decrease in ship speed in actual seas on the basis of the results of the uncertainty analysis for added resistance in waves in order to discuss whether the uncertainty is acceptable. The results of the calculation showed that added resistance in short regular waves can be measured with sufficient accuracy for practical purposes in the three facilities.