FRF. For most engineering applications, a 5 percent error may be acceptable, 

 but a correction procedure described in Appendix A will reduce such errors to 

 4 percent or less. 



Tide Gages 



23. Water level data were obtained from a National Oceanic and Atmos- 

 pheric Administration (NOAA)/NOS control station (No. 865-1370) located at the 

 seaward end of the research pier, using a digital tide gage manufactured by 

 Leupold and Stevens, Inc., Beaverton, Oreg. The Leupold-Stevens analog-to- 

 digital recorder, a float-activated, negator-spring, counterpoised instrument, 

 mechanically converted the vertical motion of a float into a coded, punched 

 paper tape record. The below-deck installation at pier sta 19+60 (Figure 2) 

 consisted of a 30.5-cm-diam stilling well with a 2.5-cm orifice and a 21.6-cm- 

 diam float. 



24. This tide gage was checked daily for proper operation of the punch 

 mechanism and accuracy of the time and water level information. The accuracy 

 was determined by comparing the gage level reading to a level read from a 

 reference electric tape gage. Once a week, a heavy metal rod was lowered down 

 the stilling well and through the orifice to ensure free flow of water into 

 the well. During the summer months, when biological growth was most severe, 

 divers inspected and cleaned the orifice opening as required. 



25. Quarterly, a NOAA/NOS tide "party," which consisted of NOS per- 

 sonnel familiar with the installation and equipment, performed a tide station 

 inspection and review. The tide gage was surveyed in from existing NOS con- 

 trol positions, and the equipment was checked and adjusted as needed. NOS and 

 FRF personnel reviewed procedures for tending the gage and handling the data. 

 Any specific comments on the previous months of data were discussed to ensure 

 data accuracy. 



Meteorological Instruments 



Anemometer 



26. Winds were measured using a Weather Service Model F420C anemometer 

 consisting of a cup rotor and spread-tail wind vane located on the top of the 

 laboratory building at an elevation of 19.1 m (Figure 2). The accuracy of the 



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