In this report we propose a forecasting method of the waves generated on currents. This method is based on the concept of the equivalent fetch length which was already reported in the 2nd report. In this method two major hypotheses were used to get over the difficulties that the group velocity of the initial waves become
negative at the windward end.
　These hypotheses are as follows:
(1) The wave of which group velocity is slightly greater than zero will occur at the windward end.
(2) The wave length of the generated wave grows in accordance with the non-dimensional fetch relation in the case of no current.
　In order to examine these hypotheses, the experiment was conducted in a wind-wave channel with a water circulation pump system.
　The wave heights were measured by using resistance-type wave gauges and wave lengths and celerities were read from the photos taken with a motor-drive camera.
　Current velocities and wind speeds were measured as functions of time.
　The hypothesis (1) was confirmed from the observed wave-lengths and current profiles.
　The hypothesis (2) was also found to be acceptable judging from the fact that the development of the calculated wave-lengths were in good agreement with the observed wave-lengths.