APPENDIX A: WAVERIDER BUOY MAINTENANCE 

 AND CALIBRATION INFORMATION 



1. This appendix presents the maintenance and calibration required for 

 the Waverider buoy gages . 



2. Datawell recommends the Waverider buoys be cleaned and new batteries 

 installed at least once every 9 months. The buoys were replaced on a number 

 of occasions during the year, as listed in the gage histories in Appendix B. 

 Considerable biological growth occurs during the summer months when the water 

 temperature is above 10° C. Antifoulant paint and at least one cleaning and 

 painting during the summer reduce the fouling problem. 



3. The buoys were calibrated at the National Oceanic and Atmospheric 

 Administration (NOAA) Engineering Support Office, Ocean Wave Instrument 

 Facility (Ribe 1981).* Ribe presents the following three correction factors 

 for use to increase wave measurement accuracy: (a) the Datawell-predicted 

 decrease in electronic sensitivity as a function of oscillation period, (b) a 

 difference error based on deviations from (a) found during NOAA's calibrations, 

 and (c) a temperature-dependent adjustment of the sensitivity due to an unknown 

 chemical reaction in the conducting fluid surrounding the Waverider accelerom- 

 eter. These three corrections and their applications are discussed below. 



Datawell-predicted Decrease in Sensitivity (DW) 



4. Waverider buoy sensitivity /A/ for the buoy electronics decreases 

 with increasing period T of sinusoidal vertical motion according to Datawell 

 as follows : 



/A/ = r , t ni/2 ^1) 



vm 



where To =30.8 sec is a characteristic period provided by Datawell. This 

 sensitivity decrease results in amplitude errors of less than 3 percent for 

 oscillation (wave) periods less than 15 sec. Figures Al through A4 present 



* References cited in this appendix are included in the References at the end 

 of the main text. 



Al 



