k. A lowering rate of 200 feet per minute for the STU was found 

 to produce no yawing. A rate of 300 feet per minute produced 

 yawing of as much as 10 degrees = 



5, The STU sank about 12 inches into the bottom sediments j, upon 

 which it rested for about one-half hour. 



Further operational tests were successfully conducted early in I962 

 during which a rehearsal of the placement of the STU and portions of its 

 mooring and recovery system was conducted in 6OOO feet of water in the 

 Santa Cnaz Basin. 



STU Instrumentation. The first STU was equipped with an electronic 

 instrument to assist in placing it gently on the bottom in a stable 

 upright position. This instrijment is an orientation- sensing device 

 which is designed to sense any departure of the STU from a vertical 

 attitude and to indicate the number of degrees at which its vertical 

 axis is inclined from the true vertical. The signal of the attitude 

 sensor is used to control the ping rate of the pinger attached to the 

 STU. When the axis of the STU is vertical it emits pings at a rate 

 of 100 per minute. With each degree of inclination from the true 

 vertical the sensing mechanism causes the pinging rate to be decreased 

 by one ping per minute. By this means the attitude of the STU was 

 determined to be 6 degrees from the vertical at the time it was placed 

 on the bottom for the 6 months exposure period at 5300 feet. The 

 attitude signal was monitored for about ^4- hours after placement and no 

 change was observed. 



It would be desirable to instrument the STU to periodically sample 

 and record information concerning local temperature^ salinity, oxygen 

 content, pH, and oxidation-reduction potential during its entire period 

 of submergence. At present, reliable, automatic, self-contained 

 instrumentation capable of collecting and storing such information 

 over a 6-month period is not available. For this reason conventional 

 oceanographic methods will be used to collect this kind of information. 

 At such time as suitable automatic instrumentation becomes available 

 at a "reasonable cost," it is expected that It will be added to this 

 program. 



An automatic self-contained recording device to measure the velocity 

 and direction of the currents in the vicinity of the STU during the 6- 

 month submersion period was attached to the STU retrieval system at the 

 time of placement. 



11 



