Section IX. ANALYSIS OF OCEAN WAVE GAGE RECORDS 



1 . Step-Resistance Wave Gages 



Strip-chart recordings taken at CERC ocean wave recording sta- 

 tions are analyzed for significant wave height, Hs, and significant wave 

 period, Ts . 



The visual method used in analyzing strip-chart recordings (as opposed 

 to automatic magnetic tape analysis) for a significant wave height and wave 

 period follows: 



a) From a chart run (normally 7 minutes), select as nearly as 

 possible the minute with a wave train which contains most of 

 the highest and most uniform waves. 



b) Determine the period of the wave selected in step a) by using 

 the wave-period template according to instructions (Figure 59). 

 When the wave period on the chart falls between two of the 

 periods shown on the template, the analyst may approximate 

 what he considers will be nearest to the exact period. For 

 example, if the period is about halfway between the 5-second 

 template and the 6-second template, then the period is about 

 5.5 seconds. 



c) Use the listing below to determine which wave should be 

 measured to get the approximate significant height of the 

 waves. The wave-height template will aid in determining 

 which wave is to be measured for height. 



Wave period (seconds) Wave to measure 



3 3rd highest 

 3.5 3rd highest 



4 2nd highest 



5 2nd highest 



6 2nd highest 



7 2nd highest 



8 or longer 1st highest 



d) With the proper wave-height template (Figures 60 and 61), 

 determine the height of the wave given by step c) by finding 

 the rectangle on the template whose top line comes nearest to 

 to the crest when the bottom line is on the preceding trough. 

 The wave height, in feet, is indicated by the number on the 

 rectangle. 



e) Records with wave heights less than 1/2 foot are listed on the 

 compilation sheet (Figure 62) as calm - without listing the 

 wave height. However, the significant wave period for such 

 records is determined and is indicated on the compilation 

 sheet . 



Ill 



