oceans. The accuracy required for such a probe is±0.1°C, and the 

 probe should record a temperature range of -2° to 32°C. 



It is recommended that the Hydrographic Office develop the per- 

 formance characteristics of a hull-mounted temperature probe and 

 that action be initiated to have such a system installed as soon as 

 possible on the USS SAN PABLO and USS REHOBOTH for test and 

 evaluation. 



c. Airborne telemetering BT and electronic helicopter BT 



An airborne, expendable BT, now in the prototype stage of 

 development is expected partially to satisfy the requirement for such 

 an instrument when its development is complete. The accuracy which 

 reasonably might be expected in the near future is ± 0.5°C for a 

 temperature range of -2° to 32°C. The expected depth accuracy is 

 ±10 feet with a depth range to 500 feet. 



An electronic helicopter BT, also in the prototype stage, is expected 

 to satisfy the requirement for such an instrument in its final production 

 form. Accuracy requirements are ±0.1 °C for a temperature range of 

 -2° to 32°C and less than two percent depth error over a depth range to 

 500 feet. 



It is recommended that the Hydrographic Office closely follow the 

 development of airborne telemetering BT and the electronic helicopter 

 BT and make every effort to obtain early production models of these 

 instruments for test and evaluation. 



2. Survey Instruments 



a. Electronic BT (single sensor, temperature continuous 

 with depth) 



The need for this instrument is urgent, since the many rela- 

 tionships that remain to be discovered in order to forecast thermal 

 structure reliably depend upon the ability to measure the thermal 

 structure with a high degree of accuracy not possible with present 

 techniques. Such an instrument should have a consistent, reliable 

 accuracy of at least ±0.01°C over a temperature range of -2° to 32°C. 

 The depth error should be less than ±6 feet over a depth range 

 to 1,500 feet. The response of the temperature sensor should allow 

 a descent and ascent rate of 200 feet per minute with a minimum of 

 a 90 percent temperature response within a 10-foot interval. Data 

 should be displayed on a rectilinear x-y recorder. Sampling rates as 



III -8 



