Simple Estimation of Wave Added Resistance from Experiments in Transient and Irregular Water Waves

Abstract

Experiments in transient water waves are well known in getting the transfer functions of ship motions. Here, we introduce a new simple method to estimate added resistance coefficients from these experiments. Using this method, we can obtain the added resistance coefficients in single transient water wave experiment instead of doing many experiments in regular waves.This new estimation method is based on Hsu's assumption, and using the Fourier spectra to separate the added resistance from surge force. Based on NSM (new strip method) and Maruo's theory, we calculated the added resistance coefficients theoretically, and compared them with the estimation results. It is another important point that the data in encounter frequency must be changed into absolute frequency domain.In experiments, three models were used : SR208 (a tanker) , SR108 (a container ship) , and SHSS (a super high speed container ship). Three models have different shapes and examined in different advance velocities. Here, all of their results will be reported.Present method is not only limited in transient water wave experiments. It can also be used in general irregular waves directly. In irregular long crested wave experiments, we obtained relatively good results as in transient water wave experiments.Using present method, we can also analyse the surge force from experimental data and can simulate the total resistance time history numerically by using the results from experiments in transient water waves.