F. MARINE SEISMIC SYSTEM (cont'd) 



13. Net weight: Transmitter: 250 pounds; Electronics: 1,000 pounds 



14. Relay rack (19 inches wide) panel space: two 72-inch racks 



15. A. C. power consumption: 1,000 watts 



16. Evaluation and recommendations: 



Since this equipment has been in operation for only a few 

 months, its performance has not yet been evaluated. 



17. References: X-21 



G. SONAR THUMPER 



1. Model: ST-8, 400 watt-seconds, designed for surface operation. 



(Models that are expected to have outputs of 1,200 and 5,000 

 watt- seconds are under development.) 



2. Manufacturer: Edgerton, Germeshausen & Grier, Inc., Boston, 



Mass. 



3. Approximate cost new: $3,500 (I960), for Thumper alone 



4. Maximum water depth in which operative: 



Empirically determined: 1,800 feet 

 Estimated: Not known 



5. Maximum penetration of sediment: 



Empirically determined: 300 feet 



Estimated: Not known, but probably greater than that of the 

 Seismic Profiler 



6. Transducers: 



Type: Transmitter: Thumper ( n The actual transducer con- 

 sists of an aluminun disk 16 inches in diameter which 

 rests against the face of a flat coil. When a large capacitor 

 bank is discharged through the coil, the eddy currents 

 induced in the disk force the disk away from the coil so 

 as to produce a large pressure pulse.* Hayward in 

 Reference X-7); Receiver: Barium titanate 



Location: Transmitter: generally towed; Receiver: optimum 

 location not known yet 



D-ll 



