3415 HYDROGRAPHIC MANUAL PaGE 252 



After the regular intervals between soundings and between positions have been 

 ordered by the officer-in-charge, the recorder is the one who sees to it that the soundings 

 and positions are taken at the required intervals, so long as constant intervals are 

 maintained. The recorder repeats aloud, for verification, all important data which 

 are called out to him to be recorded. When a sounding is reported, which, by com- 

 parison with previous soundings, appears to be possibly in error, the recorder must make 

 a special point of having the leadsman or the fathometer attendant verify the depth 

 which he is recording, and must indicate that the recorded depth has been verified by 

 making a checkmark alongside it. The recorder must call to the attention of the 

 officer-in-charge any unusual circumstances, such as a sudden unexpected deepening or 

 shoaling in the soundings. 



It is the duty of the recorder, assisted by the leadsman, to verify the length and 

 markings of the leadline against the standard each day before and after hydrography 

 and to enter the results of the comparison in the Sounding Record (see 4622). It is his 

 duty to see that the data are obtained and recorded which are required for the various 

 standard rubber stamps used at the beginning and end of each day's hydrography (see 

 813 and 816). 



3415. Fathometer Attendant 



When surveying in deep water, using an echo-sounding instrument, the duties of 

 the fathometer attendant and the recorder may frequently be combined, especially 

 where the bottom is comparatively even, the depths are easily obtained, and the interval 

 between the soundings is not too short. Generally, however, the fathometer attendant 

 should have no other duties and should be free to devote his whole attention to the 

 instrument so that the depth of the water is observed at all times and there will be as- 

 surance that no shoals nor least depths go unnoticed. A fathometer attendant with 

 no other duties must be provided at the following times, regardless of whether the echo- 

 sounding instrument is visual or graphic recording: when surveying in shoal and 

 moderate depths, where the submarine relief is irregular, when the instrument requires 

 frequent adjustment for optimum results, when readings are difficult to obtain, and for 

 all echo sounding in launches. 



A regular sounding interval is ordered by the officer-in-charge. This is usually 

 dictated by the scale of the survey and the speed of the vessel and finally by the number 

 of soimdings which can be shown legibly on the smooth sheet or which are required for 

 an adequate representation of the bottom profile. Regardless of the regular interval, 

 however, it is the duty of the fathometer attendant to note the shoalest and the deepest 

 soundings, and in each case these shall be reported to the recorder and recorded if they 

 differ by more than 5 percent of the depth from the general slope of the bottom between 

 soundings at regular intervals (see 343). 



The fathometer attendant must be familiar with the adjustments of the echo- 

 sounding instrument so that the best and most accm'ate results are obtained at all 

 times. In case of operational difficulties with which he is incapable of coping, he should 

 notify the officer-in-charge immediately. 



Where echo sounding is used in a survey it is assumed that a profile has been 

 sounded along each line and that the instrument has operated and the fathometer 

 attendant has observed it continuously between recorded soundings. If for any reason 

 the contrary is true, the fathometer attendant must notify the recorder and the 

 proper entry must be made in the "Remarks" column of the Sounding Record. 



