- 120 - 



In each data set analyzed, the number of points beyond the 

 three standard deviation limit was satisfactorily small — less than 

 one percent of the record, as expected. The mean of channels dP2, 

 dP3, and the absolute agreed well between data sets, (possibly 

 indicating minimal instrument tilt over time due to settling — see 

 Section IV. D. 4). The means of dPl and dPA often varied between sets, 

 however. It was expected that the mean of dPA might vary given the 

 signal drift observed during bench calibration. Similarly, it was 

 not surprising to encounter difficulty with dPl after considering its 

 irregularities on the bench. 



The mean values of the absolute records predicted tide levels 

 reasonably well as is shown in Table 6-2. DPG tidal calculation is 

 compared with that determined by a stilling well located near the 

 middle of the pier. Differences might be attributed to temperature 

 effects upon the absolute sensor, (see Section V.C.6) . Atmospheric 

 pressure fluctuations were accounted for. 



The mean values of dP2 and dP3 differ significantly from 

 these two channels' tare values recorded on land. In-situ mean 

 values are 2.31 V and 2.56 V for dP2 and dP3 respectively, and 0.60 V 

 and 0.71 V on land. Both subaerial . and subaqueous checks were made 

 with the same 1100 foot long cable. The subaerial tare values were 

 checked on a hot afternoon and the ocean was some 8°C cooler. But 

 it was not likely that this rise in mean voltage was due to 

 temperature changes since one expects a voltage drop with a decrease 



