In Figure 2 at x = 9.8 x 10^ and interpolated between curves for d/Ho of 

 3 and 5, reading down for H, 



H = -2^ = 0.037 



Ua 



Hs = 1.51 meters 



At a depth of 3 meters, d/Ho = 1.47, providing an H = 0.025 or Hg = 1.02 

 meters. The peak period, T , and the local wavelength would increase over 

 that at a 7-meter depth and currently must be calculated by the tables given 

 in Appendix C of the Shore Protection Manual (U.S. Army, Corps of Engineers, 

 Coastal Engineering Research Center, 1977). 



*************** EXAMPLE PROBLEM 2*************** 



GIVEN: The wind direction is predominantly from the southwest over the deep, 

 irregularly shaped water body shown in Figure 5. The windspeed to be con- 

 sidered is 49.2 feet (15 meters) per second measured on top of an instru- 

 ment shack at 13 feet (4 meters) from the ground. The air temperature when 

 these conditions occur is 50° Fahrenheit (10° Celsius) and the water tempera- 

 ture is 60° Fahrenheit (16° Celsius) . 



Figure 5, 



Scole in Kilometert 



The fetch length for this irregularly shaped water body in the wind 

 direction is determined by drawing nine radials at 3° increments 

 centered on the wind direction and arithmetically averaging the 

 radial lengths as illustrated. The average fetch in this example 

 is approximately 22.2 miles (36 kilometers). 



12 



