3 Waves 



This chapter presents summaries of the wave data. A discussion of individual major storms is 

 given in Chapter 9 and contains additional wave data for times when wave heights exceeded 2 m at 

 the seaward end of the FRF pier. Appendixes B through E provide more extensive data summaries 

 for each gage, including height and period distributions, wave direction distributions, persistence 

 tables, and spectra during storms. 



Wave directions (similar to wind directions) at the FRF are seasonally distributed. Waves appro- 

 ach most frequently from north of the pier in the fall and winter and south of the pier in the summer, 

 with the exception of storm waves that approach twice as frequently from north of the pier. 

 Annually, waves are ^proximately evenly distributed between north and south (resultant wave 

 direction being almost shore-normal). 



Measurement Instruments 



The wave gages included two wave staff gages (Gages 645 and 625), one buoy gage (Gage 630), 

 and one pressure gage (Gage HI) as shown in Figure 2. Staff gage 645 failed in May 1992 and was 

 replaced by pressure gage 641 at the same location. The gages were located as follows: 



Gage Tvpe/Muifcer 



Continuous wire (645) 

 Pressure Gage (641) 

 Continuous wire (625) 

 Accelerometer buoy (630) 

 Pressure gage (111) 



Distance Offshore 



Water Depth 



Operational 



from Baseline 



m 



Period 



238 m 



3.5 



11/84-05/92 



238 m 



3.5 



11/92-12/92 



567 m 



8 



11/78-12/92 



6 km 



18 



11/78-12/92 



1 km 



9 



09/86-12/92 



Staff gages 



Two Baylor Company (Houston, TX) parallel cable mductance wave gages (Gage 645 at sta 7-f-80 

 and Gage 625 at sta 18+60 (Figiure 2)) were mounted on the FRF pier. Rugged and reliable, these 

 gages require little maintenance except to keep tension on the cables and to remove any material that 

 may cause an electrical short between them. They were calibrated prior to installation by creating an 

 electrical short between the two cables at known distances along the cable and recording the voltage 

 output. Electtonic signal conditioning amplifiers are used to ensure that the ou^ut signals from the 



18 



