defined by eq. 10) and another range over which the current must be accounted 

 for (H is given by ( R^) H^ where R^ is defined by eq. 11). Figure 3 and 

 the values of FL and FS, once computed, can be used to determine the 

 smallest wave period beyond which currents can be neglected, TS'. For all 

 wave periods greater than or equal to TS 1 , the current can be neglected when 

 computing H from P. TS 1 is given by 



,'d W 2 



2tt f T,L 



ftS' 



TS' 



for fts' * 



where 



TS' = °° (i.e. , currents are never important) for ftS' 

 ftS' = MlN(ftA, ftB, ftC, ftD) 







(17a) 



(17b) 



(18) 



MIN( ) means take the minimum value of the numbers in parentheses, and the 



factors ftA, ftB, ftC, 

 following definitions: 



ftA = 



the 



value 



of 





(ftA 



= if 



FL 



ftB = 



the 



value 



of 





(SIB 



= if 



FL 



nc = 



the 



value 



of 





(ftC 



= if 



FS 



and ftD are estimated from Figure 3 by using the 



ft which corresponds to Rjj = 0.85 when F = FL 

 is less than or equal to 0) 



ft which corresponds to R„ = 1.15 when F = FL 

 is greater than or equal to 0) 



ft which corresponds to Ry = 0.85 when F = FS 



(19) 



is less than or equal to 0) 



ftD = the value of ft which corrresponds to R„ = 1.15 when F = FS 

 (ftD = if FS is greater than or equal to 0) 



Figure 4 gives a schematic representation of how ftA and ftD are related 

 to FL and FS for the example problem presented in the next section (in the 

 problem, ftB = ftC = 0). 



ft 



2.1 



























1.1 













- 



1.7 





FORBIDDEN 









- 



1.3 





REGION ! 







- 



1.3 

 I.I 



- 



J 







- 



0.1 





1 1 ' 



«h : "5nV/ 



► — V 

 HA rv 



R H = 0.8 V 



- 



0.7 





fj 







' ™ 







FsFM Vsi ^ / A * 



Q0 ] 





■ 



CS 





//\ 







- 



0.3 





// \ 







- 



0.1 





^^ FSI 



!fl 



_, «,_, L_ 



i , i 



- 



->J> -0J -0.6 -0.4 -02 



02 0.4 0.6 04 



Figure 4. Schematic representation of how ilA and SID are related to FL and FS 

 for the example problem in Section IV. For the problem, fiB = QC = 0. 



17 



