DEEP RECTILINEAR TOWING WITH PARALLEL TUBES^;^t 



by 



Norman W. Lord 



Hudson Laboratories of Columbia University 



Dobbs Ferry, New York 



ORIGINS 



Our need for a device which ■would tow an object in a straight line while 

 suspended at great depths arose out of sound velocimeter studies we started 

 about four years ago. 



In deep water we had encountered unexpected variations in sound velocity 

 recorded on a meter that ^vas merely suspended from an anchored ship as 

 shown in Figure 1. The so-called patch represents a small region the 

 water -space, where the sound velocity is either greater or smaller than in 

 the surrounding region. This is not a general representation for we can 

 also have spatial distributions of sound velocity whose topology would not 

 admit such a region. This would be the case of internal waves as opposed 

 to the picture here which would commonly arise from turbulent mixing. 

 However, considering the time -scale of recorded variations on the meter, 

 it is highly unlikely that they arise by anything other than some kind of 

 spatial distribution sweeping past it rather than by an internally generated 

 time variation. Swinging on such a suspended cable the meter easily 

 acquires undetermined velocities of a meter per second and this is super- 

 posed upon unkno'wn deep water currents tha.t are generally below half a 

 meter per second. Obviously we have little hope of finding the basic 

 spatial variation from the record of the meter w^hich would normally be 

 taken with respect to time. On these experiments we could made a decent 

 guess as to the statistics of the variation but the uncertainty almost equals 

 the magnitude of the parameter, not a rare state of affairs in marine 

 experiments . 



Hudson Laboratories of Columbia University Contribution No. 2Z4. 



This work was supported by the Office of Naval Research under 

 Contract Nonr -Z66(84). 



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