Page 261 hydrography 345 



For a more detailed description of tlu' duties of each of the various personnel, 

 reference should be made to 671. 



9:59:00 chronograph attendant {or sometimes the bridge) (signals the homher and notifies him 

 the size of homh to use) . 



9:59:02 bomber {signals the chronograph attendant and the bridge simultaneously, acknowledging 

 the signal and notifying them to expect an R.A.R. position on the next even time interval. The bomber 

 prepares the bomb. The radio technician checks the tuning of the radio receiver). 



9:59:45 chronograph attendant {or sometimes the bridge) {signals the bomber to light the bomb. 

 The bomber ignites the bomb, throws it overboard, and as it strikes the water ). 



10:00:00 bomber {signals the bridge and the chronograph station simultaneously that the lighted 

 bomb has been thrown overboard. This is the time of the fixed position. The fathometer attendant reads 

 the depth and silences the oscillator, if sonic. The recorder notes the time and records it in the Sounding 

 Record. The log is read and the log reading recorded in the Sounding Record. The chronograph attendant 

 notes the time and records it in the Bomb Record. The chronograph attendant switches the hydrophone 

 into the chronograph circuit and starts the chronograph). 



10:00:02 fathometer attendant to recorder {announcing the depth on position): ''Thirty-six 

 point five." {The recorder repeats and records this depth 36.5 {fathoms) . Soundings are continued at 

 regular intervals throughout subsequent events.) 



■ 10:00:10 The bomb explodes. The explosion records automat icall.y on the chronograph tape. 

 {The chronograph attendant inarks the tape to identify this registration of the bomb explosion. He has 

 noted the time interval in seconds between the "bomb over ^ signal and the explosion and records this in the 

 Bomb Record. The chronograph attendant sivitches the radio receiver into the chronograph circuit. The 

 chrnnograph continues in operation and ) 



10:00:19 The first radio signal is received from an R.A.R. station and records automatically 

 on the chronograph tape. {This signal is followed by radio returns from the other R.A.R. stations ivhich 

 are within receptive distance. The chronograph attendant marks the tape to identify each radio return. 

 After the last return has been received the chronograph is stopped, and the chronograph attendant takes the 

 times of the returns from the tape and derives the time intervals, recording all data in the Bomb Record, 

 and ) 



10:03:30 chronograph attendant {signals the bridge and r&ports) to the officer-in-charge: 

 "Bomb at ten o'clock flat." 



officer-in-charge replies: "Position twenty-three at ten o'clock flat." {Chronograph 

 attendant records the number of the position in the Bomb Record.) 



chronograph attendant to the officer-in-charge: "Position twenty-three: ESAU eight 

 fiftj'-six; DAGO nineteen thirty-five; and GOBY twenty-seven ninety-seven." {The officer-in-charge 

 records the time intervals in the R.A.R. abstract and repeats them back to the chronograph attendant for verifi- 

 cation. The offi-cer-in-charge plots the position on the boat sheet by means of the R.A.R. distances, and 

 orders a change in course if necessary.) 



10:05:00 officer-in-charge to helmsman.: "Right two degrees." 



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

 {The recorder repeats and records in the Sounding Record the new course 327° and the time it was effective. 

 The officer-in-charge issues any other pertinent orders.) 



345. MiSCELLANEOU.S OPERATIONS 



There are various operations which occur at irregular intervals m running a 

 sounding line that are discussed imder the various subheadings. 



3451. Beginning of Sounding Line 



To start a soimding line the survey vessel is navigated by the most direct navigable 

 route to the beginning of the proposed line, trial positions being taken as this point is 

 approached and the vessel being turned to head approximately on the coin-se of the 

 proposed Ime at or astern of the desired starting point. The helmsman is told what 

 course to steer, the recorder is told when to take the first position and sounding, and 



