of temperature and depth. The depth range is 

 stamped on the nose of the BT. It is either 200, 

 450, or 900 feet. 



C-3 Equipment Needed to Operate the 

 BT.— In addition to the BT, the following list 

 of equipment is required to operate the instru- 

 ment : 



1. A BT winch. Examples of winches in- 

 clude: The E6/S Winch (fig. C-3) and the 

 ACCO Equipment Division Winch (fig. C-4). 



2. ABTboom. 



3. A BT towing block, counterbalanced. 



4. Wire rope, ^-inch diameter, 7x7 stainless 

 steel, in 3,000-foot length per reel. 



5. A grid mount assembly. 



6. Metallic-coated glass slides. 



7. A slide viewer. 



8. A thermometer for measuring surface 

 water temperature. 



9. Tools (8-inch pliers, medium screwdriver, 

 and a A-inch Nicopress) . 



10. Nicopress sleeves, thimbles, swivels, wire 

 clips, and shackles. 



One other tool, which is not essential but is 

 always handy if the wire should jump the block 

 sheave or backlash, is a cable-grip (come- 

 along) . 



Shown in figure C-5 are the Nicopress tool 

 and sleeves, wire rope, thimbles, swivels, wire 

 clips, and shackles. 



C-4 Recording BT Data.— BT data are re- 

 corded on the National Oceanographic Data 

 Center Bathythermograph Log, NODC-EXP- 

 3167/10 (Rev. 3-66) (fig. C-6). It is designed to 

 provide NODC with information required for 



BT analog and digital processing and to provide 

 a standard message format for radio transmis- 

 sion of synoptic BT data for automatic data 

 processing. Instructions for completing the 

 items on the Bathythermograph Log are 

 printed inside the cover of each pad of log 

 sheets. 



C-5 Taking a BT. — Making a BT lowering is 

 described by the term "Taking a BT.'' It is a 

 relatively simple operation ; nevertheless, a new 

 operator should practice lowerings and recov- 

 eries with a dummy BT before undertaking 

 the lowering with an actual instrument. 



Certain operations are necessary to assure 

 that good data are obtained. Taking a BT 

 includes the following procedures: 



Step 1. Check the operating instruction man- 

 ual for the model winch to be used. The hand 

 lever on the E6/S winch (fig. C-3) serves both 

 as a brake and clutch. It has three positions: 



(1) When it is vertical, the Avinch is in neutral 

 and the drum can be turned in either direction ; 



(2) When it is pushed outboard to the engaged 

 (hoist) position, the motor turns the drum and 

 spools on the wire; (3) When the lever is pulled 

 inboard toward the operator, to the brake po- 

 sition, the drum is locked and cannot be rotated. 

 On other models the operation is different. The 

 operating lever and the brake are separate. 



Figure C-3. E 6/S BT winch operating positions. 



C-2 



Figure C-t,. ACCO Equipment Division BT winch. 



