To obtain a reasonatly smooth cvirve it 'became necessary to consider 

 the average of the tracking data obtained in a thirty minute interval 

 (seven groups of 20). This data is plotted in Fig. 2. Pertinent tide 

 information is also given in the figure. 



The data shows a clear pattern related to the tidal cycle, with 

 the maximxam deviation of the buoy occiirring during the peak ebb tide. 

 In the first two hoxirs after planting the system exhibited an 

 unusually large amount of drift as shown by the irregular track at 

 that time. Twelve hours after planting the computer suddenly dropped 

 out of synchronization with the SCUFU with a resultant error in the 

 track position. The data for the four hours following this event 

 was given a constant correction on each axis to account for the shift 

 in the time base. At that point (approximately O73O local time) a 

 correction was entered into the range computer to correct for the 

 shift and the tracking was continued for 25 more hours. An abrupt 

 shift of h feet in depth at 0200 of the second day indicates that a 

 small shift in the synchronous relation of the SCUPU and the computer 

 may have occurred at that time. 



Continuous tracking was discontinued at O9OO in preparation for 

 the recovery of the buoy. An acoustic release mechanism near the 

 smchor was triggered on command from the surface and. the buoy and 

 smchor line allowed to float freely to the surface. The tracking 

 data obtained during ascent indicates that the terminal velocity 

 during ascent was about 10 ft. /sec. compared to the maximvmi during 

 descent of less than seven. This is reasonable since the net 

 (negative) buoysuicy of all components was 1000 lbs. in descent and 

 1100 lbs. (positive) in ascent with the drag contribution of the 

 anchor removed. 



Data from the 1+2 hours that the buoy was on the bottom 

 indicates that the maximxmi shift of position is about ten feet, 

 occurring primarily along a north- south line at the time of maximum 

 ebb tide. It is apparent that the tidal effect is not uniform in 

 the opposing parts of the cycle. It should be noted that tides in 

 this area are weak, the rise and fall being less than one foot, 

 and that a few current measurements made at mid-depths indicated 

 a maximum tidal velocity of about 0.2 knot. The water deepens to 

 the northward going to over 2000 fathoms. We can only speculate 

 that this influences the currents to produce the observed effect. 



287 



