12 



^10 - 



.? 8 - 



^ 6 - 



-t: 4 - 



2 - 



x:Measured Cumulative Vlave Height Data, 22 

 Apr. 1948 To 30 Apr. 1949, Long Branch, N.J. 

 (Hall and Herron, 1950) 





Extremes- 

 Height-^ 



Exponential Regression Line 



- 



\ 





\ 'n 



- 



T 



I 



\ 



*y '^\Average | 



1 LJU 



J Cycle Len( 

 I In 10 



-^ Cycle Le 



L .„J 



Jthl \»^'^ 



— ' 0.3a---^W 



Medion^x 

 ngth h«— Height \ 



1 1 1 1 1 1 Ml 



0.1 0.5 1 5 10 50 100 

 Pet of Wave Heights Greoter Than Ordinate 



Figure 2. Graphical definition of statistics of exponential 

 cumulative wave height distribution. 



statistics, the extreme significant wave height exceeded 12 hours per year (0.137 

 percent) is 



so. 137 



H^ + 5.6 a 



(4) 



where Hg is annual average significant wave height, and a is the annual 

 standard deviation of significant wave height. For simplicity, the period as- 

 sociated with this extreme wave condition is taken to be the average significant 

 wave period Tg , with fair justification. The wave statistics Hg , a, and 

 Tg should be defined by one or more full years of daily or more frequent meas- 

 urements. 



Using equations (2), (3), and (4), equation (1) can be rewritten as 



2^^;. 1 sinh^ l^^l tanhf^ 



,2/5 



ir^CHg + 5.6 o)2 

 0.03Y'(gf2/2Tr)^ 



(5) 



and the values of y', Hg, a, and Tg determine a single value of (2TTdj^/L). The 

 value of d£ can be accurately determined using the iterative root-finding cal- 

 culator program presented in the Appendix. Alternatively, for y' = 1-6 (quartz 



