The wave resistance and amplitude spectrum of two geosim-models and their actual ship were directly determined by means of the longitudinal parallel cut of their wave patterns, which has been developed by Newman and Sharma. Through this investigation, the authors discuss the following problems to be solved for the practical application of the newly developed experiments. The effect of the transverse location of the measuring probe on the results of the experiments, was mainly caused by the error due to local disturbance in the vicinity of the model and also due to the truncation of the records of wave pattern. The authors show that the truncation error is far more significant factor than the other and that it is mainly governed by the ratio of Y/M, in which M and Y are the length of records and the distance of the measuring probe from the center line of the towing tank, respectively. If the wave resistances were determined in the same condition for the ratio of Y/M, the scale effect of the wave resistance seems to be minor factor. Some experiences in the experiments on determination of wave resistance of the ship are also briefly explained.