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HYDROGRAPHIC MANUAL 



7-4 Descriptive report text. — The text of 

 the descriptive report shall be typewritten 

 on letter-size paper with a left-hand margin 

 of 114 inches for binding. Only one copy 

 shall be forwarded with the records unless 

 the sheet is to be plotted at a processing 

 office, in which case the report shall be for- 

 warded in duplicate. 



Each text shall be titled "Descriptive Re- 

 port to Accompany Hydrographic Survey 



H (Field No. ) " (insert registry and 



field numbers). The scale and year of the 

 survey, the names of the survey vessel or 

 party and the chief of party shall be shown. 



The text should be written clearly and con- 

 cisely. No information required for com- 

 plete understanding of the records shall be 

 omitted but verbose explanation of details 

 shall be avoided. When reference is made to 

 a hydrographic feature on the smooth sheet, 

 the latitude and longitude of the feature 

 shall be given. In order to provide uniform- 

 ity of reports, the text shall be arranged 

 under the following lettered headings and in 

 the order appearing here. 



A. Project. — Include the project number 

 and date of original instructions, and the 

 dates of any supplemental instructions and 

 letters which are pertinent. 



B. Area surveyed. — Briefly describe the 

 area covered by the survey and the adjacent 

 coast. State the general locality, approxi- 

 mate limits, and inclusive dates of the sur- 

 vey. If the survey makes a junction with 

 prior surveys, mention these by registry 

 numbers, scales, and dates ; and list by regis- 

 try or field numbers all contemporary sur- 

 veys with which junction is made. 



C. Sounding vessel. — List all ships and/or 

 launches used to obtain the soundings and 

 the colors used to identify the work of each 

 unit, except when all hydrography is accom- 

 plished by the ship named in the title. 



D. Sounding equipment. — Identify by 

 types and serial numbers all echo-sounding 

 instruments used, state the type of other 

 sounding equipment used, and the general 

 area or depths in which each was used. 

 Briefly describe method used for determining 



' echo sounder corrections. Discuss any faults 



in equipment which affected the accuracy of 

 the soundings. 



E. Smooth sheet. — State how and where 

 the smooth sheet projection was made. When 

 the boat-smooth sheet method of plotting is 

 used, state the maximum probable error of 

 positioning resulting from final computation 

 of calibration data. If the smooth sheet is 

 plotted by use of film positive copies of the 

 boat sheet, state the percentage of positions 

 protracted directly on the smooth sheet. Dis- 

 cuss the extent of adjustments required in 

 transferring positions. 



F. Control. — State the method or methods 

 of horizontal control used and define the 

 areas in which each was used. Explain in 

 detail any unusual or substandard methods. 

 List the shore stations used for electronic 

 systems of control and state how each sta- 

 tion was located. List graphic control or 

 other planetable sheets by field or registry 

 number. List the photogrammetric compila- 

 tions used for transfer of signals. Identify 

 compilations which are advance manuscripts 

 and give the print date if knowm. 



G. Shoreline. — Give the source of shore- 

 line details listing all topographic sheets or 

 photogrammetric compilations used unless 

 they are listed in F. State whether the 

 transfer of shoreline and topographic details 

 has been verified. 



If any of the shoreline or topographic de- 

 tails were found to be inaccurate or to have 

 changed since the date of the original sur- 

 vey and were revised by the hydrographer, 

 identify the parts revised and state the 

 methods used. Any discrepancies between 

 photogrammetric and hydrographic locations 

 of offshore details must be explained in 

 detail. 



If the low-water line is not defined by the 

 soundings, describe the conditions which 

 prevented this. 



H. Crosslines. — State the percentage of 

 crosslines run and discuss any discrepancies 

 at crossings. Explain methods used to recon- 

 cile differences at crossings. 



I. Junctions. — Discuss the agreement or 

 disagreement in depths at junctions with sur- 

 veys listed in B. If an adjustment is re- 



