98 



Generation, Growth and Propagation of Waves 



James (1954) checked Neumann's theory by comparing it with ocean 

 wave records and obtained very satisfactory results; the results found by 



G-26 



Fig. 43a. Duration and fetch graph for wind speeds from 22-36 knots as a function of 



duration and fetch respectively. , isolines for duration in hours; , isolines 



for fetch in nautical miles. 



Rattray and Burt (1956), however, who studied the wave heights in a storm 

 weather situation, are not so good, so that it is not possible to form a final 

 judgement. 



The investigations by Darbyshire (1952) are based on direct measurements 

 of the development of wind sea spectra off the British west coasts and in 

 lakes. He found empirical relations between wind and waves for fully arisen 

 sea as well as for the times of generation with different duration and fetch. 

 The basic assumption of the physical relations is the following: there is no 

 energy exchange between the different wave components of the spectrum, 

 so that they progress independent of one another, with the corresponding 



