218 



HYDROGRAPHIC MANUAL 



must be displaced some distance it may be 

 comiected to the position by a dotted line 

 in the same color. A solid line leader shall 

 not be used. It is essential that position 

 numbers cannot be misread as soundings on 

 photographic copy, yet will not be so small 

 as to require the use of a magnifying glass 

 to read them. 



6-52 Record of plotting. — The smooth 

 plotter shall maintain a record of his actions 

 in the sounding volume, using a pencil of 

 identical color for all entries and corrections. 

 A checkmark, in the same color, shall be 

 placed beside the recorded data for each 

 position plotted and accepted. Each recorded 

 change of course and each note in the re- 

 marks column should be checkmarked as the 

 information is applied to the smooth sheet. 

 All revisions, amendments, or new informa- 

 tion shall be entered in the same color and 

 initialed. The original recorded data shall 

 never be erased. Corrections and revisions 

 shall be made by neatly crossing out the 

 recorded data and entering the correct data 

 above the erroneous data. An erroneous 

 entry which cannot be logically revised on 

 the basis of available information shall be 

 rejected and this action indicated by a capi- 

 tal "R" adjacent to the entry. Authority or 

 reason for revision or rejection shall be stated 

 in the volume unless it is clearly obvious. 



When least depths or other critical in- 

 formation are not plotted and not rejected 

 for the reason that they are superseded by 

 data recorded elsewhere in the sounding 

 volumes, a note shall be entered adjacent to 

 the data not plotted stating where the super- 

 seding data are recorded, as "see pos. 22d — 

 Vol. 3— page 48." 



Only those positions which are actually 

 plotted shall be checkmarked. When esti- 

 mated positions or protracted positions are 

 transferred from the boat sheet to the smooth 

 sheet, this fact shall be noted in the sounding 

 volume. 



Stamp No. 38 (Fig. 70) is impressed at 

 the end of each day's work and the smooth 

 plotter shall enter his initials in the appro- 

 priate place to indicate that the positions 

 have been smooth plotted. 



6-53 Soundings. — ^The soundings and re- 

 lated hydrographic detail required for the 

 compilation of nautical charts are the princi- 

 pal products of hydrographic surveying. 



Before proceeding with the plotting of 

 soundings the smooth-plotter shall check the 

 record of processing accomplished on the 

 sounding records. Completion of each phase 

 of processing from check-scanning the fatho- 

 grams through checking the reduced sound- 

 ings should be indicated by the initials of 

 the persons responsible therefore in the ap- 

 propriate spaces of Stamp No. 38. If the 

 initials have not been entered, the smooth 

 plotter should assure himself that the work 

 has been done, or perform the necessary 

 work and have it checked before penciling 

 soundings on the sheet. 



The plotting of soundings on the smooth 

 sheet usually follows the same procedure as 

 plotting positions ; that is, the plotter begins 

 with the first position in Volume 1 and plots 

 the soundings in the order in which they 

 were recorded. This is not mandatory, and 

 it is sometimes preferable to plot soundings 

 on crosslines first or to complete the plotting 

 of an intensively developed area without 

 regard to chronological order. Soundings on 

 crosslines shall be retained in preference to 

 soundings on the regular system of lines ex- 

 cept where the latter are shoaler. When 

 the chronological order is not used there is 

 danger that some essential information may 

 be overlooked, particularly when the plotter 

 is unable to complete the sheet because of 

 transfers of personnel or other reasons. 



The soundings should be accurately and 

 neatly penciled on the smooth sheet in ac- 

 cordance with instructions contained in the 

 following sections. Although the soundings 

 are subject to verification or revision in the 

 office, they may be used for charting prior 

 to verification. If the field work and smooth 

 plotting are accurate and complete only 

 minor revisions of the chart may be neces- 

 sary after final review of the sheet. On the 

 other hand, inaccurate or incomplete work 

 may result in charting false information, 

 thus creating a hazardous situation. 



6-54 Identification of least depths. — 



