3442 HYDROGRAPHIC MANUAL PaGE 260 



be substituted, as for instance the recorder may use a bell, or a sounding clock with a 

 bell, to indicate to the leadsman when to sound. 



9:59:45 recorder to anglemen: "Stand by!" (The nnglemen pick up their sextants, find the re- 

 spective objects in their sextants, and keep their angles approximately on.) 



9:59:50 recorder to leadsman: "Sound!" (This order may also be given by whistle, bell, or other 

 signal. The recorder issues this order an appropriate number of seconds before the end of the time interval, 

 depending on the depth, speed of the boat, and skill of the leadsman, so that the leadline will he vertical at 

 the desired time. The leadsman swings the lead and heaves it out ahead of the boat. The lead sinks. 

 The launch approaches the lead. The leadsman hauls in the slack leadline. The anglemen prepare to 

 mark the angles.) 



10:00:00 recorder to anglemen: "Mark!" {The leadline is vertical. The anglemen mark the 

 angles. The leadsman reads the depth and ) 



10:00:02 leadsman to recorder: "Nine — eight." (The recorder repeats and records 9.8 (fathoms). 

 The leadsman' s assistant starts hauling in the leadline, and the leadsman coils it preparatory for the next 

 sounding. The anglemen read their angles, and ) 



10:00:04 left angleman to recorder: "Sixty-seven fifteen." (The recorder repeats and records 

 67° 15' . The officer-in-charge sets the left angle on the protractor.) 



10:00:08 right angleman to recorder: "Forty-one oh-eight." (The recorder repeats and records 

 the right angle 41° 08' . The officer-in-charge sets the right angle on the protractor and plots the position. 

 As he plots he announces the names of the stations used in the three-point fix.) 



10:00:20 officer-in-charge to recorder: "The fix is BAT-FIG-OLD." (The recorder repeats and 

 records the names of the stations. After the position has been plotted the position number is frequently 

 verified. A change in course is ordered if necessary.) 



10:00:40 officer-in-charge to coxswain: "Right two degrees." 



coxswain (repeating): "Right two degrees. The course is now three twenty-seven." 

 (The coxswain is now steering a course 2° to the right of the previous course. The recorder repeats and 

 records the new course 327°. For a considerable change in course he also records the effective time.) 



3442. An R.A.R. Fix 



Hydrography is most complicated when the soundings are obtained by the echo 

 method and the control is by R.A.R. The sequence of events that precede and 

 follow one R.A.R. position and the approximate times at which these events occur on 

 the average are given in the following relation. It is to be understood that the clock 

 times preceding and following 10:00:00 are varied depending on the efficiency of the 

 personnel, the distance from the R.A.R. stations, and the amount of difficulty experi- 

 enced in interpreting and plotting the results. The time of the position is 10:00:00 

 and all of the data obtamed are recorded in the Records as of this time; other times 

 given below are merely to illustrate the approximate timing of the various activities 

 in connection with obtaining the fix and sounding at 10:00:00. 



The various operations in connection with obtaining an R.A.R. fix take place in 

 different parts of the vessel; the bomber is located at a station on the quarter-deck; 

 the radio technician and the chronograph attendant are stationed in the radio room or 

 in adjacent rooms where they can communicate orally with one another; the other 

 personnel are usually stationed on the bridge or in the chartroom adjacent thereto. 

 The personnel at each of these stations can communicate with the other stations only 

 by signal or by telephone, voice tube, or loudspeaker communication system. 



As in 3441 the sequence of events is only carried through one complete position, 

 and it is to be understood that continuous soundings are obtaiiied at regular intervals 

 and the sequence of events described herein is repeated at each successive R.A.R. 

 position during hydrography. 



