figures, the numerals near the dots indicate the actual distance from the sailing line. The measured results are in good agreement with the calculated ones of cal-2 under the condition at lower ship speed and with them of cal-1 under the condition at higher ship speed. Both calculated wave periods indicated almost the same values and the both qualitative tendencies are similar to the measured ones.
Fig.5 shows the comparison of calculated wave profile by cal. -2 and measured one. The both of bow divergent waves are in good agreement with each other. Therefore, we cansuggest that the estimation method by cal.-2 presents the satisfactory and reasonable wave profiles of ship waves.
Fig.5 Time series of calculated and measured ship waves by displacement vessel.
(2) HIGH SPEED VESSEL
In the first cases, the effects of waves by varying the distance from the sailing line at the constant ship speed (16k｡?) were investigated. The measured and estimated maximum wave heights and wave periods of ship waves are shown in Fig. 6. The measured maximum wave height are higher than the calculated ones of cal-2 but less than ones of cal-1. The both calculated results are in close agreement with the measured ones relatively In the lower figure of Fig.6, the measured wave period decreases increasing the distance. Generally the measured maximum wave periods are less than both calculated ones.
In the second case, the effects of waves by varying the ship speed in the constant distance from the sailing line (20m, 70m and 100m) were investigated. The measured and calculated maximum wave heights and wave periods of ship waves at the distance of 100m are shown in Fig.7. The measured wave heights are in good agreement with the calculated ones of cal-2 under the condition at lower ship speed and with them of cal- 1 under the condition at higher ship speed. These qualitative tendencies are similar to the ones in the case of displacement type. Both calculated results of wave periods indicated the almost same values except for the range of higher speed However, the discrepancy between the calculated wave periods and the measured ones in the case of higher speeds are shown. This seems to suggest that the measured ship waves do not always propagate to the wave direction obtained from the linear wave theory in the case of higher ship speed. Fig.8 shows the comparison between the calculated and the measured wave profiles of ship waves by high speed vessel. These results show closer agreement, though the calculated stem divergent waves are larger than the measured ones. This is due to the reduction of measured waves by effects of the propeller and confused stern flows.
Fig.6
Measured and calculated ship waves heights and periods of the high speed vessel versus distance from the sailing line at the constant ship speed.
