Figure C-5. The Nicopress tool and sleeves, wire rope, thimbles, swivels, wire clips, and shackles. 



Examine the winch installation to assure that 

 the wire comes across the top of the drum. Eun 

 the free end of the wire through the towing 

 block at the end of the boom. This block is of 

 a special counterbalanced design for BT use. 

 Make certain that the winch drum and block 

 are properly lubricated. 



Step 2. Connecting BT to Lowering Wire. — 

 Cut off rusted, kinked, or frayed wire and 

 make a new connection using a thimble with 

 three Nicopress sleeves or wire clips. Check the 

 swivel and if the BT does not have a built in 

 swivel include one in the connection. Connect 

 the lowering wire thimble to the BT swivel 

 with a shackle. NOTE: More BT"s are lost by 

 poor connections than from any other cause. 

 Another important precautionary measure is 

 to paint the last 50 feet of the BT wire a bright 

 color. This will signal the operator during 

 retrieval to be on the immediate lookout for the 

 BT, preventing accidental "two-blocking" and 

 loss of the instrument. It is unwise to trust the 

 counter dial on any BT winch. 



Step 3. Inserting Slide in BT. — It is impor- 

 tant that the slide is inserted in the BT 

 properly. 



Slide the BT sleeve forward toward BT nose 

 (fig. C-7). This will uncover the stylus assem- 

 bly and slide holder. 



Hold slide between thumb and index finger 

 with coated side up. 



Insert the slide into the hole on the side of 

 the BT, and push the slide into its bracket. The 

 edge of the slide with the beveled corner goes 

 in first, with bevel towards tlie nose of the BT. 



Push the slide all the way in. Occasionally 



check the grooves of the slide holder to make 

 sure they are clean and free of glass chips. Also, 

 check the spring to assure that the slide is being 

 held firmly in position. 



Move the sleeve back to cover the opening 

 prior to putting the BT over the side. This will 

 bring the stylus assembly in contact with the 

 glass slide. 



Step 4. Putting the BT Over the Side.— 

 Wlien permission has been obtained from the 

 bridge, the BT can be put over the side. 



Hold the BT at the rail; take up the slack 

 wire. 



Lower the BT into the water to such a depth 

 that it rides smoothly just below the surface 

 (fig.G-8). 



Put on the brake and hold the BT at this 

 depth for at least 30 seconds to enable the 

 thermal element to come to the temperature of 

 the surface water. 



Turn on the motor, so that power is available 

 instantly for the rest of the operation. 



Set the counter on the winch to zero. 



Step 5. Taking the Sea Surface Reference 

 Temperature. — While the BT is being towed at 

 the surface, the sea surface reference tempera- 

 ture is taken. Any reliable thermometer can be 

 used. The most common method of obtaining 

 the temperature is to collect a bucket of surface 

 water, immediately immerse the thermometer in 

 the water, stir the thermometer with a circular 

 motion, and read the thermometer with the 

 stem still immersed in the water. Make several 

 readings to assure a valid observation (fig. C-9). 



Record the sea surface reference temperature 

 on the Bathythermograph Log. 



C-3 



