THE NEL DEPTH REGULATION 

 EQUIPMENT 



Description 



The NEL depth regulation equipment (figs. 2 and 3) 

 is based on a principle previously neglected in attempts to 

 stabilize vertical wire cable movements. Since many of the 

 earlier efforts had been defeated by the effects of friction 

 and weight, it was decided to utilize the increase of water 

 pressure with depth as a means of preventing the unwanted 

 vertical wire motion. 3 



An experimental depth sensor (fig. 4) is used to con- 

 vert the vertical ship motion into pressure changes. It is 

 submerged at a depth equal to one -half of the wavelength of 

 the surface waves (fig. 5). At this depth the orbital action 

 of the surface waves particles is negligible, 3 and the chang- 

 ing wave motion has no effect on the sensor. 



The depth sensor consists of a pressure bellows 

 mechanically linked to a synchro motor. The shaft of the 

 latter rotates in proportion to the vertical depth changes of 

 the sensor which are synchronized with the vertical motions 

 of the platform from which the sensor is suspended. When 

 the platform moves downward, the sensor also moves down, 

 experiences an increase in pressure, and causes a direc- 

 tional synchro movement. When the platform moves up- 

 ward, the directional synchro movement is in the opposite 

 direction. Thus, an increase in pressure on the sensor 

 tends to raise the submerged equipment and a decrease in 

 pressure tends to lower it. 



3. Sverdrup, H. U., Johnson, M. W. and Fleming, R. H. 

 The Oceans, Their Physics, Chemistry, and General Bi - 

 ology, Prentice -Hall, 1942 



