short between them. It was calibrated prior to installation by creating an 

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

 recording the voltage output. Electronic signal conditioning amplifiers are 

 used to ensure that the output signals from the gauge are within a 0- to 5-V 

 range. Manufacturer-stated gauge accuracy is about 1 .0 percent, with a 0. 1- 

 percent full-scale resolution; full scale is 14 m for Gauge 625. This gauge is 

 susceptible to lightning damage, but protective measures have been taken to 

 minimize such occurrences. A more complete description of the gauges' 

 operational characteristics is given by Grogg (1986). 



Buoy gauge 



One Datawell Laboratory for Instrumentation (Haarlem, The Netherlands), 

 Waverider buoy gauge (Gauge 630) measures the vertical acceleration pro- 

 duced by the passage of a wave. The acceleration signal is double-integrated 

 to produce a displacement signal transmitted by radio to an onshore receiver. 

 The manufacturer stated that wave amplitudes are correct to within 3 percent 

 of their actual value for wave frequencies between 0.065 and 0.500 Hz (corre- 

 sponding to 15- to 2-sec wave periods). The manufacturer also specified that 

 the error gradually increased to 10 percent for wave periods in excess of 

 20 sec. The results in this report were not corrected for the manufacturer's 

 specified amplitude errors. However, the buoy was calibrated semiannually to 

 ensure that it was within the manufacturer's specification. 



Pressure gauges 



One Senso-Metrics, Incorporated (Simi Valley, CA), pressure transduction 

 gauge (Gauge 111) installed near the ocean bottom measures the pressure 

 changes produced by the passage of waves creating an output signal that is 

 linear and proportional to pressure when operated within its design limits. 

 Predeployment and postdeployment calibrations are performed at the FRF 

 using a static deadweight tester. The sensor's range is to 25 psi (equivalent 

 to to 17 m of seawater) above atmospheric pressure with a manufacturer- 

 stated accuracy of +.0.25 percent. Copper scouring pads are installed at the 

 sensor's diaphragm to reduce biological fouling, and the system is periodically 

 cleaned by divers. 



One Paroscientific, Incorporated (Redmond, WA), pressure transduction 

 gauge (Gauge 641) was installed near the ocean bottom on an instrument pile 

 under the pier at station 7 + 80. Calibration is similar to that performed on 

 Gauge 111. The sensor's range is to 45 psia (equivalent to to 30 m of 

 seawater) with a manufacturer-stated accuracy of +0.01 percent. A perforat- 

 ed copper/nickel plate protects the sensor's diaphragm from biological fouling, 

 and the system is periodically cleaned by divers. 



20 



Chapter 3 Waves 



