TM No. 377 



The four electrical leads from the wave meters were taped to the vertical 

 instrument rod (see figure IV-l6). The four single-pin male connectors mated 

 with female connectors, which,, in turn, were spliced to the four-conductor, 

 shielded, neoprene- jacketed cable made by the Belden Manufacturing Co,, Chicago, 

 Illinois). The cable above the splice was securely taped to the vertical 

 instrument rod, leaving sufficient slack so that, if a strain were accidently 

 taken on the electrical cable, the connectors could not unplug. The Eelden 

 cable was led upward parallel with the main support cable to the catwalk rail, 

 and then inboard and up to the 722 Sanborn two-channel system in the BBELS 

 laboratory. 



This system was used for the wave measurements listed as BBELS-5, 7> 8., 

 9, 10, 11, 12, and 13. The BBELS-5 measurements were made without the benefit 

 of a back guy. The measurements listed as BBELS -1^, 15, and 16 were made with 

 an additional anchored guy shown in the figure IV-15« This guy led from the 

 rail adjacent to the meter wheel vertically to a l60 kg lead clump set on the 

 bottom. A tension of about 50 kg was drawn on this anchored guy by means of 

 a turnbuckle led from a pipe fastened to the catwalk rail (see figure IWI7). 



The vertical rod supporting the wave meter was fastened to the anchored 

 guy by means of messengers used in tripping Nansen bottles > The two messengers 

 were placed on the anchored guy. Each was fixed to the vertical instrument 

 rod, one aboire and one below the meter, with stainless steel hose clamps. The 

 meter system was then lowered, allowing the two messengers to slide down the 

 anchored guy. (See figure IV-18.) 



In practice, the wave meter was fastened to the main support cable and, 

 with the north, south, and back guys slack, lowered while the Belden elec- 

 trical cable was payed out, When the meter reached the desired depth beneath 

 the wave troughs (registered on the meter wheel), the north and south guys were 

 pulled taut, thus keeping the main support cable vertical, and excess slack was 

 taken out of the electrical cable.. Then the back guy was tightened to bring 

 the horizontal rod firmly positioned at the apex of the inverted pyramid 

 formed by the four guys. Much care was taken to keep equal tension on the 

 south and north guys so as not to tilt the suspended system. 



The method of suspending the LIMDUM I system (used to measure simultaneous 

 vertical velocities at two levels) was much simpler, since complete horizontal 

 stability was not necessary for determinations of the vertical motions. Also, 

 a slight rotation of the system about the vertical rod axis should not affect 

 the w measurements. For LIMDUM I observations of the vertical velocity 

 component w, only the single main support cable was used-. During BBELS -11, 

 a northeast storm occurred, and a series of vertical velocity measurements 

 were made from the east end of the catwalk (which, at the time of measurement, 

 was the windward side of the BBELS ). 



For measurements with LIMDUM I of the horizontal velocity component u, the 

 suspension involving all guys was used, since the (horizontal) meters had to be 

 fixed with respect to the azimuth angle in the direction of the waves (see 

 figures 11-10 and III-4)* 



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