78. Residual time series plots comparing both tide and wave gages at 

 various scales are contained in Appendix I. Residuals between selected pairs 

 of tide gages over the specified interval are plotted in Plates 1-10. The 

 mean of the residual is included, which would theoretically be equal to zero 

 over a sufficiently long time interval if the assumptions made in selecting 

 the datum are valid. As noted earlier, TG2 experienced a failure near 



20 August, and redundant gages were deployed at a later date, so the intervals 

 of simultaneous operation do not all coincide. 



79. An obvious characteristic of residual TGI - TG2 is that it is al- 

 most always positive, and the mean is in fact near +0.06 ft. To an optimist, 

 this could be evidence of a continuous current from west to east along the 

 outside of the breakwater, but the "current" is also evident in residual TG6 



- TG2 at almost the same average head, this time flowing to the northwest, as 

 well as in the remaining two residuals using TG2 . Additionally, the trend is 

 not verified in residual TGI - TG6 . Though its amplitudes appear reasonable, 

 as indicated by the monthly mean elevations in Table 2, TG2 apparently 

 suffered a timing error that placed it out of phase with the other gages- - 

 perhaps associated with its early failure- -and should not be used for 

 additional analysis. 



80. Other residuals display diurnal and semimonthly harmonics indica- 

 tive of tidal curents oscillaing on and off shore, but with low mean differ- 

 ences. The means of the residuals of over the entire deployment, which range 

 from 0.0001 to 0.0038 ft, indicate an overall accuracy commensurate with the 

 stated specifications of the sensor and well within the experimental 

 requirements . 



Benchmark check 



81. Unlike the primary and backup tide gages, the wave gages were 

 installed nearshore on harbor structures and were accessible (via diving 

 rodmen) to standard leveling. LB4 was surveyed on two occasions to a nearby 

 benchmark (Hicks 1987). Details are contained in Appendix C. The average of 

 the two surveys is 17.60 ft below MLLW. 



82. Two data sets, A and B, cover the period of consideration. A 

 simple average of their two mean water depths gives 



-20.65 y-20.77) = _ 2Q n (3) 



83. Adjusting to MLLW by the constant used in the previous analysis, 



31 



