recorder case. Plug in the power-supply cable. 

 Adjust the dial on the front of the recorder 

 case to read about 52. This is done with the 

 large knob in the center of the case. Stand 

 clear of the step-resistance gage of the wave 

 staff. Turn the main power supply switch to 

 ON position. Next, adjust the manual lever 

 on the side of the Brush recorder so that the 

 pen trace is on the bottom line (nearest the 

 front of the case) of the chart paper. After 

 this is done, turn the main power switch to 

 Oi^F position. 



3. After making sure that the main power 

 switch is off, attach the 25-foot-long-wire leads 

 to the uppermost and lowermost contact 

 points, and lower the leads over the side into 

 the water. Have about a foot of exposed wire 

 at the overboard ends, with small weights 

 attached to steady them in the water. 



4. When both leads are in the water, about 

 12 feet apart and away from the ship, stand 

 clear of the gage and turn the main power 

 supply switch to ON position. With the 

 large variac knob in the center of the case adjust 

 the voltage so the recorder pen is on the top line 

 (nearest the back of the case) of the chart 

 paper. Turn OFF the main power switch. 



5. After making sure that the main power 

 switch is off, detach one of the leads from the 

 contact points. With the voltage setting ob- 

 tained in 4 above check the zero trace again by 

 turning ON the main power switch and adjust- 

 ing the manual lever on the side of the pen 

 motor so the trace is on the bottom line of the 

 chart paper. 



6. Turn the main power switch to OFF posi- 

 tion, attach overside lead and repeat step 4. 



7. Repeat steps 4 and 5 as often as necessary 

 to achieve the specified results. 



8. Label the calibration run on the chart 

 paper and record the voltage setting. Retain 

 the calibration run with the record of each wave 

 staff observation. 



10-20 Lowering and Operating the Electric 

 Wave Staff. — The procedure for lowering the 

 wave staff over the side and obtaining the ob- 

 servation is carried out as follows: 



1. Make sure that the main power supply 

 switch is in the OFF position. Lift the staff 

 and damping disk over the side. With the two 

 handling lines and the retrieving line on the 

 damping disk, lower the assembly into the 

 water. 



2. When the staff is waterborne, cast off the 

 handling lines, keeping them clear of the contact 

 points, and continue to lower the damping disk. 

 Allow slack in the electrical cable and retrieving 

 line. 



3. Turn the main power supply switch to ON 

 position, and mark the point on the chart paper 

 when the staff becomes upright in the water and 

 settles to its normal depth. About 6 feet should 

 be projecting in calm water. 



4. Pay out the cable, with the floats attached, 

 and the damping-disk retrieving line. Allow 

 slack at all times. If either line becomes taut, 

 the staff will list and record incorrectly. Pay 

 out both line and cable, of which there is about 

 1,000 feet, until a record of at least 7 minutes 

 has been obtained from the time the staff be- 

 came upright. A 20-minute record should be 

 obtained whenever possible. If the cable should 

 run out and become taut during the observation, 

 shut off the recorder and make note of this point 

 on the chart, then haul the staff an appropriate 

 distance toward the ship by means of the damp- 

 ing-disk retrieving line. Some of the cable 

 should be hauled in at the same time to prevent 

 excessive slack and possible fouling of the damp- 

 ing disk. Slack the retrieving line and cable. 

 When the staff again becomes upright, turn ON 

 the main power switch and complete the ob- 

 servation. 



10-21 Retrieving and Securing the Electric 

 Wave Staff. — The procedure for retrieving and 

 securing the wave staff is carried out as follows: 



1. After the run is completed, turn OFF the 

 main power and haul in the retrieving line and 

 cable, keeping the strain on the line and not 

 on the cable. 



2. When the staff is alongside, retrieve the 

 handling lines with a boathook or grapnel. 

 With the two handling lines and the damping- 

 disk retrieving line, hoist the staff and damping 

 disk aboard. 



3. Lay the staff on deck, keeping the contact 

 points clear of the deck or any metal objects. 

 Stand clear of the gage and turn the main power 

 switch to ON position. Check to see that the 

 zero trace has returned to the lowest line of the 

 chart paper, the one nearest the front of the 

 case. If the zero trace is off by more than 5 

 lines, the step-resistance gage must be cleaned 

 with fresh water, dried, and waxed, and the 

 entire run repeated. 



4. If the zero trace has returned properly to 

 the lower line, turn OFF the main power switch 

 and disassemble the wave staff. Wipe dry the 

 step-resistance gage and clean and grease the 

 coupling joints. It may be necessary to wash 

 down the gage section with fresh water once in 

 a while to prevent formation of a salt coating 

 which would tend to hold a film of water on the 

 gage. This film would produce erroneous re- 

 cordings. 



106 



H. O. 607 



