113 



The cable leads were interfaced with FRF power and 

 data-logging equipment and regular data recording commenced that 

 evening. 



B. Instrument Orientation 



The orientation of the instrument with respect to magnetic 

 north was determined using a submersible digital compass and 

 conventional diving compasses. The digital compass was mounted at 

 the end of a five-foot length of aluminum angle. One diver recorded 

 the value indicated by the compass while another diver held two feet 

 of the free end of the angle onto the top of each PVC arm of the 

 instrument. In this way, the digital compass was at least six feet 

 from the steel cradle. Compass headings were recorded for each arm 

 twice — once by each of the two divers — and then averaged. The 

 orientation of each arm was also measured by securing a diver's 

 compass around the end of an arm using the compass wrist strap. 

 Measurements were taken three times for each arm using two different 

 compasses and then averaged. All of the values recorded for each 

 technique along each arm agreed reasonably well within a technique. 

 The wrist compass, strapped around an arm, indicated the heading 

 perpendicular to the arm. Accordingly, ninety degrees was subtracted 

 from each wrist compass reading to give the heading of the arm. 



