Page 775 records and reports 831 



These records should be just as clear, complete, and self-explanatory as the Sound- 

 ing Records and the same precautions are required in the recording (see 81). 



831. Position Records 



When it can be done conveniently it is always desirable to keep the complete record 

 of a hydrographic survey in one book — the Sounding Record. Using certain types of 

 control, however, it is necessary to record the position data in a separate record, and it 

 may occasionally be more convenient to do so even when using three-point fix control. 

 The sextant observers may have to station themselves on the flying bridge, or elsewhere, 

 at some distance from the echo-sounding instrument, where it is inconvenient and con- 

 ducive to error, to record both the position data and soundings in the same recoid book. 

 There is no objection to separate records in such cases but the greatest care must be 

 taken to correlate the two records accurately by time and position numbers. 



In sm-veys controlled by R.A.R., the position data are received at the chrono- 

 graph station, usually in the radio room and frequently some distance from the ship's 

 bridge or the plotting room, and a separate Bomb Record must be used for the data. 



Position data for dead reckoning, and often in connection with R.A.R. surveys, are 

 abstracted on a special form designed for this purpose. 



Astronomic sights also are recorded and computed separately. 



8311. Bomb Record 



In surveys controlled by Radio Acoustic Ranging (R.A.R.) , described in chapter 6, 

 the Bomb Record (Form 670) is the official record of the R.A.R. position data. For 

 plotting positions based solely on R.A.R. distances, the data shall be complete in the 

 Bomb Record, and reference to other records should not be necessary. But the dead 

 reckoning and all supplemental data, such as bearings and sextant angles, shall be 

 recorded in the Sounding Record. R.A.R. position data shall not be repeated in, nor 

 copied into, the Sounding Record. 



R.A.R. distances measured to locate buoy stations (see 2533, 2534, 2573, and 

 2574) shall also be recorded in the Bomb Record. This Record shall be the original 

 source of the data used to determine buoy positions by this method (see 8324). R.A.R 

 distances measured to determine the velocity of sound experimentally shall also be re- 

 corded in the Bomb Record, but the corresponding observations or measurements to 

 determine the horizontal distances are either recorded in the Sounding Record or on 

 special forms designed for taut-wire measurements (see 8323). 



Entries in the Bomb Record are made at the chronograph station, usually by the 

 chronograph attendant (see 6712). The entries must be clear and complete and the 

 general instructions for recording in the Sounding Record must be followed (see 81 and 

 811). 



The Bomb Record and the Sounding Record are identical in shape and size and are 

 very similar in outward appearance. A sample double page of the Bomb Record is 

 shown in figure 184, in which the approved manner of recording R.A.R. data is illus- 

 trated. The Record is designed for the use of shore stations and it is arranged so that 

 the returns from two stations may be recorded in the space to which one position number 

 is assigned. But R.A.R. control is now planned with a view to getting at least three 

 bomb distances at a position, so each double page of the Record shall be used as a 

 continuous horizontal record, the data for one position being carried across both pages, 



