Tg = 8.6 e 



0.421 



1 + 



0.145 X 1 X 14 

 V47.66 



Tg = 8.6(1.52) (1.294) = 16.9 s 



Alternately, by equation (3-64) it is seen that 



computing the values of wave height and period to three significant figures 

 is not intended to imply the degree of accuracy of the method; it is done to 

 reduce the computational error. 



Referring to Figure 3-43, H^^ = 18.5 meters corresponds to the relative 

 significant wave height of 1 .0 at r/R = 1 .0 , the point of maximum winds 

 located, for this example 67 kilometers (36 nautical miles) to the right of 

 the hurricane center. At that point the wave period T is about 16 

 seconds. At r/R =1.0 to the left of the hurricane center, from Figure 3- 

 43 the ratio of relative significant height is about 0.62, when H^ = 0.62 

 (18.5) = 11.5 meters. This wave is moving in a direction opposite to that 

 of the 18.5-met er wave. The significant wave period for the 11.5-meter wave 

 is Tg = 12.1 -^11.5/9.81 =13.1 seconds , say 13 seconds. 



The most probable maximum wave is assumed to depend on the number of waves 

 considered applicable to the significant wave Eq = 18.5 meters. This 

 nvraiber N depends on the length of the section of the hurricane for which 

 near steady state exists and the forward speed of the hurricane. It has 

 been found that maximum wave conditions occur over a distance equal to the 

 radius of maximum wind . The time it takes the radius of maximum wind to 

 pass a particular point is 



t = 



R_ 

 V, 



67000 m 

 14 m/s 



= 4780 s = 1.33 h 



(3-65) 



the number of waves will be 



-|; = ^'^«« 



The most probable maximum waves can be obtained by using 



H^ = 0.707 



«o V 



log 



e n 



(3-66) 



(3-67) 



For this example, the most probable maximum wave is obtained by setting n = 

 1 and using equation (3-67) 



H^ = 0.707 (18.5) yjlogg^= 31.1 m , say 31 



m 



Assuming that the 31-meter wave occurred, then the most probable second 

 highest wave is obtained by setting n = 2 , the third from n = 3 , etc., 

 thusly : 



3-87 



