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Figure 7. (A) The oceanographic research vessel USS MARYSVILLE with thermistc 

 chain deployed. 



EQUIPMENT 



The NEL thermistor- chain ' assembly of drum, hoist, 

 links, and weight weighs 37, 500 pounds. The deck units consist 

 of the hoist, chain, generator, and the drum on which the chain 

 is wound (fig. IB). The chain is composed of flat links 1 foot 

 long, 10 inches wide, and 1 inch thick. A 2,300-pound, 

 torpedo-shaped weight at the end of the chain tends to maintain it 

 in a more vertical position during towing, and represents the 

 maximum depth of observation. One hundred pairs of insulated 

 electrical leads fit through grooves inside the flat links, and the 

 electrical wires (harness) are connected to the temperature 

 sensors at 25-foot intervals (fig. 1C). The upper ends of the 

 electrical leads are connected to a recorder located in the ship's 

 laboratory, where signals from each of the 34 sensors are 

 scanned electronically. 



The scan cycle time is 12 seconds. The order of sensing is 

 from the surface to the deepest sensor, or thermistor bead. The 

 chain, inclined backward at an angle, moves forward with the 

 ship, and the sensing takes place in an approximately vertical 



