3.0 PILOT PROJECT DESIGN 



The internal waves to be observed are expected to have a 

 minimum period of 15 minutes and a minimum half amplitude 

 of 10 meters. Of primary importance is the accurate, continu- 

 ous measurement of water temperature. 



The pilot project has the dual objective of obtaining internal 

 wave and engineering data which are both of immediate value and 

 essential for successful design of a future larger scale experiment. 

 A long-lived system providing both spectral and synoptic data for 

 not less than two years and hopefully for five years is our ultimate 

 goal. 



The balance of this section is divided according to the three 

 distinct aspects of the telescope design: Structure, Sensors, and 

 Data Acquisition. A general arrangement drawing is given in 

 Figure 3-1. 



3.1 Telescope Structure 



The structure illustrated in Figures 1-1 and 3-1 is designed to 

 hold the sensors on a horizontal line with the great stability required 

 for proper data interpretation, which is 3 meters displacement in 

 the vertical and sensor line directions and 12 meters in the cross- 

 sensor line direction. Examination of available current data has led 

 us to believe that the magnitude of the current at 700 meters and 

 deeper is usually less than 0. 3 knots, and this value was therefore 

 used in sizing the structure to meet the stability requirement. The 

 major parameters determining stability are excess buoyancy, which 

 pre-stresses the array, and cable drag. The current data and local 

 legend also indicated that the structure should be strong enough to 

 withstand a 1. 5 knot current. The effect of a strong current is both 

 a large scale deflection and greatly increased cable tensions. These 

 factors are of primary importance in the design of moorings, chafing 

 gear, float depth rating and cable strength. Finally, the failure mode 

 resulting from an extreme current condition should be cable parting 

 rather than float implosion, in order to permit recovery and examination 

 of the array. 



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