300 400 500 



FETCH, F, IN NAUT. MILES 



600 



Figure 8. < Wave height and wave period as func- 

 tions of distance from coast line at 5^ to 35^ after 

 a v;lnd of 30 knots started to blovv' over an undisturbed 

 water surface. 



for every fifth hour after the wind started. First, small waves 

 are formed, probably by eddies striking the sea surface. At the 

 coast the waves remain low, but off the coast they travel with 

 the wind and grow as they receive energy by push and pull. When 

 the wind has blown for 5 hours one finds that with increasing 

 distance from the coast the waves increase rapidly in height and 

 period out to a distance of 35 miles. There the waves are 8.4 

 feet high with a period of /+.? seconds. Beyond 35 miles similar 

 waves are present but there exists a striking difference between 

 conditions inside and beyond the 35-mlle point. Inside of 35 miles 



22 



