area of interest which has a mean slope of 8. 7 percent and whose direction of maxi- 

 mum slope is along true bearing 287° . The mean expected error for sonar azimuths 

 at right angles would then be approximately 348 yards. 



CONCLUSIONS 



One of the purposes of a tactical range is the evaluation of weapons systems ac- 

 cording to their performance. An attempt must be made to sort out the shortcomings 

 of the system from those related to the medium and its boundaries. 



We have demonstrated in this paper that the environmental effects may be signifi - 

 cant in this area. Suppose, for example, fire control effectiveness evaluations in- 

 volving bottom bounce sonars are conducted in the tactical range west of Kauai. If 

 these tests produce observed fire control errors of 300-500 yards, the expected errors 

 due to bottom slope which we have mentioned become extremely important. The ob- 

 served fire control errors may not be the fault of the system at all, but may be almost 

 entirely due to the effects of the medium. 



ACKNOWLEDGMENTS 



MPL participants in the Kauai work in addition to the authors were M. S. McGehee, 

 senior engineer; D. E. Boegeman, senior electronics technician, and H. J. McQuern,, 

 laboratory mechanician. Liaison with APL, University of Washington, was provided 

 by Dr. G. R. Garrison of APL. His help in the survey work and in acquiring the navi- 

 gational assistance of the FPS-16 Radar Facility were sincerely appreciated. Dx. 

 C. D. Lowenstein of MPL provided considerable assistance in the data analysis and 

 his comments on the manuscript were both pein:inent and helpful. 



In addition the continued assistance of the officers and crew of the R/V OCONO - 

 STOTA under Captain Terry Hansen is gratefully acknowledged. 



REFERENCES 



Garrison, G. R. 1965 Oceanographic evaluation of a Fleet Range Site ofif the west 

 coast of Kauai, Hawaii. APL-UW 6513, Applied Physics Laboratory, Uni- 

 versity of Washington, Seattle, p. 35. 7 January 1965. 



McGehee, Maurice S. 1964 A high resolution differentieil pressure gage for deep sea 

 use. Marine Physical Laboratory, University of California, San Diego 

 Technical Memorandum 145. 27 February 1964. 



Loughridge, Michael S. 1964 A deeply-towed narrow-beam echo sounder. Proceed- 

 ings of First U. S. Navy Symposium on Military Oceanography, Washington, 

 D. C. 17-19 June 1964. 



Spiess, F. N., H. W. Menard and D. C. Krause. 1959 Some sources of sonar bear- 

 ing errors. U. S. Navy Journal of Underwater Acoustics, v. 9, no. 2, pn 

 259-268. April 1959. 



220 



