accurate calibration of the system for depth was impossible. Rough 

 computations made by considering apparent wire angle at the surface 

 indicated a depth of 366 meters; however, frequency indications on 

 the receiver showed an approximate depth of 212 meters. 



It appears that conditions during this test were rather extrane 

 as far as currents were concerned, and the results show the necessity 

 for laboratory-controlled pressure tests. 



Calibration procedures were extremely simple and only required 

 the connection of a hydraulic pressure line to the pressure poten- 

 tiometers in order to apply a known pressure accurately simulating 

 the desired depth. This hydraulic te3t was subsequently run on a 

 calibrated hydraulic dead-weight tester. The calibration was run 

 from atmospheric pressure to 575 p.s.i.g. in increments of 25 p.s.i.g., 

 and then back down to atmospheric pressure in the same 25 p.s.i.g. 

 steps. In calibration tests, as in field operation, the RBA-6 re- 

 ceiver is tuned to the transmitted signal. The frequency indicated 

 en the dial is then interpreted in feet or fathoms from the plotted 

 curve. A descriptive plotting chart has been prepared, which allows 

 easy and quick reference. 



With this information, it was then possible to compute the 

 actual maximum depth that was obtained during the depth tests aboard 

 the M/V GERDA. This calculation shows the maximum depth to be approxi- 

 mately 263 meters ( +1 percent). 



The testing of pressure seals would require a test chamber. 

 However, well -designed pressure seals generally perform in the expected 

 manner and, if properly handled, very seldcm fail. 



The telemeter functioned properly during the depth test, and 

 inspection of the O-ring seals showed no leakage. The junction box 

 on the rear of the QBG transducer leaked, and sufficient water entered 

 to cause a partial short of exposed terminals. During preparation 

 for this test, pre cauti oris were taken concerning this particular weak 

 point by filling the cavity in the box with glycerine. However, the 

 cable leading through the gland nut contained a hemp filler that 

 absorbed the glycerine and left an air space. The extreme hydrostatic 

 pressure to which this fitting was exposed during the test forced the 

 rubber gland into the empty chamber and allowed water to enter. This 

 condition has been eliminated by use of a different type of cable, 

 containing no filler or air space. 



Tem perature 



No calibration curve has been run on the temperature system; 

 however, it is a simple procedure to perform in the laboratory. The 



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