TM NOc 377 



lower cross pipes, Moreover, a wire suspension system could be lowered and 

 raised with ease, providing sampling at many depths over a relatively short 

 time span, Also, with a main suspension guy lead from the west side of the 

 catwalk, instrumentation could be positioned relatively far out from the legs 

 and cross members* This is because of the large overhang of the catwalk. 

 The vertical projection to the water of the west end of the catwalk is about 

 5 meters from the nearest diagonal support pipes and about 12 meters from 

 either of the main west legs. This is a much greater horizontal distance 

 than could have been provided by any feasible rigid support requiring bracing 

 to the horizontal cross pipe. 



In spite of these favorable attributes of a suspended system, there was 

 a degree of uncertainty about how the perturbations of the waves would affect 

 the suspended meter. There is, after all, no substitute for having a current 

 meter fixed rigidly in inertial space. 



As with most new techniques for scientific measurements, the method of 

 wave measurement became more refined as experience was gained. Essentially, 

 three successive modifications of the suspension system were used on the BBELS= 



Figure IV-15 shows the arrangement of the suspending cables and the asso- 

 ciated hardware for support of the wave meters, (The insert in figure IV-15 

 depicts the simple electrical circuitry,) The wave meters— either in the 

 OMDUM configuration (shown in figure 11-15) to measure u and w simultaneously, 

 or the LIMDUM configuration (shown in figure II-17) to measure spatially 

 separated pairs of w's or u , s--are affixed to a vertical rod (shown in the 

 figures),, This rod, in turn, is fastened to the horizontal mounting rod of 

 the suspension system in the manner shown in figure IV-16, Welded to the 

 horizontal rod is a vertical piece of L-stock about 18 cm in length. The 

 vertical instrument rod fits into this L-stock and is held rigid by two 

 stainless steel hose clamps, 



A counterweight was suspended on a ^-meter-long wire pennant from the 

 bottom of the vertical instrument rod, The weight consisted of from three 

 to six 2 kg sash weights lashed together., To each end of the horizontal 

 mounting rod,, which is about 3 meters in length, was attached a stabilizing 

 guy as shown in figure IV-15- These guys led to the handrail stanchions on 

 the northwest and southwest corners of the BBELS (main level ■= exterior 

 walkway). The main support cable was shackled on to the top pad eye in the 

 vertical instrument rod (figure IV~l6), On the same shackle was attached 

 the back guy, which led eastward to the center of the catwalk beneath the 

 platform housing, 



The main support cable, which was used to raise and lower the entire 

 wave meter system, was led through a meter wheel fastened to the handrail 

 at the end of the catwalk, and then to the hand winch fastened to the grating 

 floor of the catwalk (see figure IV-17), The east, west, and back guys were 

 stainless steel wire rope 2>k mm in diameter. The main support cable and the 

 anchored guy (when used) were stainless steel wire rope 6„3 ™n i n diameter. 



