Accuracy verification of the 2D spectral AIS method by the hull monitoring data

Accuracy validation of the 2D spectral AIS method (AIS method using two-dimensional wave spectrum; 2D-AIS method) using hull monitoring data of a large ore carrier is discussed. The AIS method predicts the response of actual ships using AIS-based ship position data, hindcast wave data, and response characteristics data. The conventional AIS method uses representative parameters( H , T , θ ) from wave spectrum modeling. The modeling involves many uncertainties. By using the 2D wave spectrum as it is, the effect of uncertainties associated with wave spectrum modeling is investigated. Compared to the analysis of the monitoring data conducted in this study, it was found that the 2D-AIS method improves the accuracy to about 15 %, while the conventional AIS method shows an error of up to about 35 % compared to the actual measurements in the long-term maximum expected values. This enhancement is attributed to the inability of the modeled wave spectrum to accurately represent the two-peak wave spectrum observed in extreme sea states, leading to a deficiency in reproducing wave frequency components corresponding to peak frequencies of the response. The findings underscore the effectiveness of the 2D-AIS method in refining long-term hull stress estimations, thus offering valuable insights for enhancing the safety and performance of hull structures. • A 2D-AIS method (AIS method using two-dimension wave spectra) for estimating the long-term distribution of hull stress is proposed. • Based on the hull monitoring data of a large ore carrier, a comparative analysis is conducted between the conventional AIS method, which employs modeled wave spectra, and the 2D-AIS method, which directly incorporates 2D wave spectra derived from hindcast data. • Results reveal that while the conventional AIS method exhibits a maximum long-term expected value error of approximately 35 % compared to measured values, the 2D-AIS method significantly improves accuracy to about 15 %. • This enhancement is attributed to the inability of the modeled wave spectrum to accurately represent the two-peak wave spectrum observed in extreme sea states. • The findings underscore the effectiveness of the 2D-AIS method in refining long-term hull stress estimations.