SECTION 7.0 



ERRORS INTRODUCED BY OPERATING TECHNIQUES 



Errors introduced by the operating technique take into consideration two distinct features: 

 (1) Errors produced by the technique itself, and (2) Errors produced by the personnel oper- 

 ating the Bathythermograph. 



7.1. Errors Produced by Handling the Bathythermograph 



The major faults of the Bathythermograph from an operational standpoint 

 may be summarized as follows: 



a. Can be operated with slide not in all the way. 



b. Can be broken by leaving in the sun. 



c. Can destroy the trace in the surface layer when recovered: from the cast. 



While it would be considered advantageous if the instrument could be designed 

 not to operate unless proper seating was first accomplished, it is still the fault 

 of the personnel not to seat the slide properly. 



Again a fault of the personnel, the instrument's pen arm can be seriously 

 bent if left in the sun exposed to too high a temperature. Some manner of dis- 

 engaging the pen arm would eliminate this very common error. 



Destruction of the upper part of the trace is often caused by the skipping and 

 bouncing of the instrument upon recovery. This has been eliminated in newer 

 instruments by a pen lifting device which disengages the pen on the "up" trace 

 of the cast in the last fifty feet approaching the surface. Sometimes, however, this 

 disengaging device, actuated by the protecting sleeve, renders the Bathythermo- 

 graph inoperative unless care is taken to have the sleeve in the proper position, 

 this proper position being left to the attention of the operating personnel. The 

 result has been blank slides. 



7.2. Errors Produced by Supplementary Equipment 



The principal supplementary equipment is the winch used to raise and lower 

 the Bathythermograph. One of the major operational difficulties is bringing the 

 Bathythermograph aboard, especially in rough weather. A one speed winch causes 

 the Bathythermograph to swing violently in an arc as it frees the water, and some- 

 times results in jamming the Bathythermograph against the davit blocks. An ad- 

 justable speed winch would facilitate handling and boarding of the Bathyther- 

 mograph. 



As previously pointed out, there is evidence to support the fact that the speed 

 of raising and lowering the Bathythermograph can effect the trace. A number of 

 Bathythermographs lowered experimentally by hand showed no hysteresis whereas 

 other Bathythermographs lowered under the same conditions, but on the winch, 

 showed considerable response hysteresis. It is quite possible that the speed of raising 

 and lowering the Bathythermograph can introduce a source of error under certain 

 conditions. 



In view of the high degree of damage the Bathythermographs suffer, it seems 

 advisable to study a little more thoroughly the design and operation of the winch and 

 davit system used to lower and raise the Bathythermograph. Extra expense in im- 

 proving the supplementary equipment might be more than compensated for by the 

 savings in the Bathythermographs and improvement in the Bathythermograph data. 



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