Weight in Air 



Weight in Water 



Hydrophone Height Above Base 



Diameter of Base Ring 



C. G. Above Base in Air 



C. G. Above Base in Water 



Yoke Pivot Above Base 



Free Fall Velocity 



502 lb 

 360 1b 

 15ft 

 12 ft 

 32.45 in. 

 30.53 in. 

 34.0 in. 

 2.86 ft/sec 



hydrophone 



mast (aluminum) 



yoke (aluminum 



(in up position) 



The yoke is horizontal 



when the assembly is 



installed in water. 



base ring 

 (pvc) 



BARSTUR has performed 

 satisfactorily to date (Okura, 1969). 

 Difficulties have been experienced 

 with only two hydrophones. One 

 hydrophone has become inoperative 

 and will be replaced. A second hydro- 

 phone is experiencing a shadow effect 

 which may possibly be caused by the 

 proximity of a rock outcropping or 

 ledge. Neither difficulty appears 

 attributable to unsatisfactory foun- 

 dation performance. Tracking is still 

 good in the rest of the range; however, 

 a shift of more than 20 feet would have 

 been required before variations would 

 be noticed. A detailed survey and 

 inspection were planned for the fall 

 of 1969, but have been postponed. 

 Some difficulty has also been expe- 

 rienced with the hydrophone cables 

 at the junction box (Good, 1970). 

 During the winter storms of 1969- 

 1970, several were torn loose from 

 their bottom securing system (dead- 

 weight bags) and became entangled 

 about the junction box (Black, Bruce, 

 and Herrmann, 1970). Remedial steps 

 were taken during the summer of 1970. 



Figure 9. BARSTUR hydrophone 



assembly. (From N POL A, 

 1969.) 



Bermuda Range. An acoustic 

 range was established in 1961 by the 

 Navy near the Island of Eleuthera in 

 the Bahamas (Moothart, 1969). Water 

 depths at the site vary from 3,000 to 1 2,000 feet. Although no sediment records 

 are available, nearshore material was assumed to be coral, and offshore sediments 

 were assumed to be even harder. The bermuda system is composed of numerous 

 acoustic arrays supported by a variety of footings. 



Difficulties with the Deep Ocean Basin Acoustic Cable Source (DOBACS) 

 have been reported. These problems are apparently not the result of unsatisfac- 

 tory foundation performance. The DOBACS, which weighs 35,000 pounds in 

 air and is approximately 25 feet in diameter by 50 feet high, was positioned at 

 a water depth of 3,000 feet on a relatively small, steeply sloped (30 degrees) 

 plateau. The plateau is approximately 200 by 400 yards in area. The struc- 

 ture was leveled by a gimbal system after placement. 



17 



