.hold the float at a fixed location on the cable 



.permit rotation of the float around the cable 



.protect the cable jacket from implosion shrapnel 



.avoid point loading and cable jacket wear 



.be capable of rapid attachment 



.permit spooling the cable under tension 



. cost under $2. 00 per float 



.be available in very short lead time 



The solution is shown in the photographs in Figure 3-14, It 

 is in two parts. The float sleeve is attached to the cable before 

 spooling on the barge. A short piece of polyethylene tubing, 

 sawed helically, is spread and slipped over the cable jacket. Two 

 PVC threaded couplings (standard pipe-fitting hardware) are then 

 threaded over the ends of the tubing, one from each end. The 

 couplings cut their own thread in the soft tubing and clamp it and 

 themselves firmly in place. A molded urethane float clamp is 

 later folded over the float sleeve and clamped to the float handle. 

 This technique has worked very well, is nearly indestructable, 

 and meets all requirements admirably. It has two disadvantages: 

 The PVC nuts must be slipped over the cable before the termina- 

 tions are applied and later translated to their proper positions 

 (one can imagine the activity required to locate the nuts on 16 foot 

 centers on the three signal cable shots! ). The other disadvantage 

 is that a cable so encumbered with float attachments cannot be 

 spooled under tension without some damage to the cable jacket. 

 These difficulties were worked around satisfactorily, however, 

 as described later. We have a design concept for a combination 

 sleeve /float clamp which can be clamped in place in one rapid 

 operation and avoid the above mentioned disadvantages, but further 

 work on this improved device is not justified at the present time. 



3.2 Sensors 



The task of determining the presence of internal waves is accom- 

 plished by monitoring the temperature of the water at fixed points. 

 As the internal wave passes the measuring stations, the surrounding 

 water is displaced by water at a different temperature; hence, the 

 time history of the internal wave. 



As indicated earlier, the measuring stations are restricted in 

 their motion by the taut array. However, since the stations cannot 

 be held absolutely rigid in one position, the vertical motion of Sta- 

 tions 2 and 4 are measured by pressure transducers in order to moni- 

 tor deflection and permit application of a correction factor in the data 

 reduction. 



210 



