325 HYDROGRAPHIC MANUAL PaGE 210 



have been adequately proved or disproved, and where additional work appears neces- 

 sary. Such a daily examination enables the hydrographer to keep all the necessary 

 development and investigation up to date with the progress of the systematic sounding, 

 and to avoid uneconomic returns to areas supposedly completed. 



When practicable to do so, the Chief of Party should review the work of his 

 subordinates daily by a similar critical and thorough examination of the boat sheet 

 (see 3411). 



325. Details on Completed Boat Sheet 



3251. Positions and Numbers 



The positions and the numbers of the positions should be inked legibly and in the 

 assigned color as the work progresses, or at least before another day's work is begun. 

 Expert lettering is not required. (See 3311 and 3312.) 



3252. Lines Connecting Positions 



The successive positions of the survey vessel along a sounding line should be 

 connected by pencil in accordance with the instructions for the smooth sheet (see 7682). 

 The connecting lines should reflect any appreciable changes in course between positions. 



The end and beginning of adjacent lines shall be connected by a pencil line to 

 indicate the approximate course of the vessel, with an arrow at the midpoint indicating 

 the direction. Sounding around turns between ends of lines is not required and should 

 be omitted except where there would otherwise be no sounding. In this case the 

 vessel's track around the turn should be plotted more accurately and in accordance 

 with the instructions in 7682. On turns in shoal water continued sounding may be 

 needed so that the hydrographer can be kept informed as to the depth of water under 

 the vessel, even if these soundings are not needed for the survey. 



Where a sounding line parallels the sinuosities of a narrow waterway where it is 

 impracticable to maintain straight courses between positions, or where large changes 

 in course are made between positions, the actual track of the vessel shall be shown on 

 the boat sheet with great accuracy because only by reference to this record can the 

 soundings be correctly plotted on the smooth sheet. 



3253. Soundings 



The soundings, reduced to the approximate sounding datum (see 152), shall be 

 inked on the boat sheet in black as the work progresses; each day's work shall be inked 

 daily. 



It is usually practicable to ink the soundings of small-scale ship surveys while 

 the sounding is in progress ; by contrast, it is generally impracticable to do this on large- 

 scale launch surveys because of engine vibration and because the soundings and positions 

 are taken so frequently there is no time for inking. 



When it is practicable to ink the soundings as they are taken, a carbon copy of that 

 part of the Sounding Record which contains the soundings, the clock times, and the 

 position numbers will be foimd of advantage (see 81). 



3254. Depth Curves 



Depth curves are required on a boat sheet for an adequate study of the results of a 

 survey, and to ensure that the area has been effectively sounded and satisfactorily 

 developed (see 353). The intervals between depth curves should follow the rules given 



