TM No. 377 



channel strip chart recorder (manufactured by Esterline Angus Corp., 

 Indianapolis, Indiana), giving a continuous record of the tide level. This 

 strip record was hand-read, providing digitized amplitude values (cm) ob- 

 tained at equi-time spaced intervals of 1.8 ksec (30 minutes). These values 

 are tabulated in appendix Co 



The first period of current observation (series i) extended from 29 April 

 through 8 May. The instrument sampling interval was set for 19 minutes with 

 a 1 -minute film advance time, giving an effective sampling time of ^ T ~ 20 

 minutes (1.20 ksec). The cylindrical current meter was suspended about 5 meters 

 beneath the sea surface by a 1.9 cm diameter nylon line, which was fastened 

 to the west end of the catwalk under the main BBELS housing (see figure IV-3)« 

 The meter was counter-weighted at it base by a 10 kgm weight to provide added 

 stability and damping from the horizontal accelerations of the longer period 

 waves a 



The record actually extended through 11 May (1000 hours); however, on the 

 afternoon or evening of 10 May, during a period of high winds and rough seas, 

 the instrument was lifted over one of the north diagonal pipe supports of the 

 tower. In this position, the instrument was quite close (within 2 meters) to 

 the northeast leg and within 1 meter of the surface at low water. Hence, the 

 meter would have experienced violent wave motions and produced data quite 

 incommensurate with the data at the original depth of 5 meters. The period 

 of reliable data was therefore considered to extend from 29 April (1300 hours) 

 through 8 May (.1240 hours). A summary of the results is given in table IV-1. 



Table IV-1. Long Term Current Measurements from BBELS: Series I (1964) 



Dates and Time 29 April (1300 hours) through 



8 May (12^0 hours) 



Mean Depth of Meter (m) 5 



Sampling Period T (ksec) 765.6 ( 2 12 hours htf* 1 ^^) 



Sampling Interval T (ksec) 1„2 (20ninutes) 



Total Data Points N 6kQ 



Mean Speed (cm sec -1 ) lif.l 



Variance of Speed (cm 2 sec™ 2 ) 29 . 5 



Mean Azimuth (°T) 290 



Speed of Net Displacement 6.0 



Vector (cm sec" 1 ) 



Range of Speeds (cm sec" 1 ) if„9 - 36.6 



The mean speed over the sampling period of 212.66 hours (76.5°6 ksec) was 

 lif.l cm sec" 1 , with a standard deviation of 5.39 c *n sec" 1 and a range of values, 

 from if .9 to 36.6 cm sec" 1 . The speed of net displacement vector had a magnitude 



79 



