orientation of the hammer, strength of the hammer blow, placement of the 

 hydrophone or accelerometer along the pile length, and any movement of 

 the hydrophone or accelerometer during testing. Deciphering and elim- 

 inating the individual causes for discrepancies in the received signals 

 is extremely difficult and highly unlikely. Therefore, it is recom- 

 mended that further pursuit of the impact testing technique be discon- 

 tinued. 



5. An economic cost/benefit analysis of each of the technically fea- 

 sible timber inspection techniques is planned in this fiscal year. 

 Subsequently, one of the timber inspection systems should be selected 

 for prototype development based upon measurement accuracy and economic 

 cost/benefit. 



REFERENCES 



1. R.L. Brackett, W.J. Nordell, and R.D. Rail. Inspection requirements 

 analysis and nondestructive testing technique assessment for underwater 

 inspection of waterfront facilities, Civil Engineering Laboratory, Tech- 

 nical Note N-1624. Port Hueneme, Calif., Mar 1982. 



2. J.S. Muraoka. "Effects of marine organisms," Machine Design, 1968. 



3. Thomas B. O'Neill. 1982 inspection of experimental marine piling at 

 Pearl Harbor, Hawaii, Civil Engineering Laboratory, Technical Note N-1672. 

 Port Hueneme, Calif., Jul 1983. 



4. J. Agi. "Nondestructive testing of marine piling," in Fourth Pro- 

 ceedings of Nondestructive Testing of Wood Symposium, Vancouver, Wash., 

 Aug 1978. 



5. E.C. Haderlie. Sounds produced by wood boring marine animals and 

 attempts to detect these animals in waterfront structures using passive 

 sonic techniques, Naval Postgraduate School. Monterey, Calif., 1979. 



6. R.L. Brackett. Underwater inspection and nondestructive testing of 

 waterfront structures: A state-of-the-art assessment report, Civil Engi- 

 neering Laboratory. Port Hueneme, Calif., Jun 1978. 



7. C.A. Keeney. Ultrasonic inspection of wooden waterfront structures, 

 Civil Engineering Laboratory, Technical Memorandum 43-81-08. Port Hueneme, 

 Calif. , May 1981. 



8. A. Singh and W.D. Jolly. Nondestructive inspection techniques for 

 timber waterfront structures, Southwest Research Institute, Contract 

 Final Report Task 1. San Antonio, Tex., Sep 1982. 



(Contract N62474-82-C-8282) . 



9. NCEL underwater computerized tomography inspection study, Contract 

 Report, Phase I Report. Santa Barbara, Calif., Ametek, Jun 1982. 



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