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HYDROGRAPHIC MANUAL 



which will be of use in evaluating the smooth 

 plotting and in verification of the smooth 

 sheet. Unusual adjustments made in smooth 

 plotting and deficiencies in field data should 

 be noted where not clearly explained in the 

 record books, such as sounding lines rejected, 

 lines not plotted because of unresolved dif- 

 ferences in depth, signals whose positions 

 are questionable, and unresolved discrepan- 

 cies at crossings. 



6-77 Title and number. — Each completed 

 smooth sheet transmitted to the Washington 

 Office shall be accompanied by a copy of Hy- 

 drographic Title Sheet, Form 537, and the 

 original shall be inserted in the descriptive 

 report (see 7-2). The title is inked on the 

 sheet at the office prior to final approval of 

 the survey. 



The field number (see 1-13) and the 

 registry number (see 1-14) of the survey 

 shall be entered in Stamp No. 42. The perma- 

 nent registry number is preceded by the letter 

 "H" denoting a hydrographic survey. 



6-78 Field examinations. — The occasion- 

 al small field investigations for which no 

 specific project instructions are written (see 

 2-3) are registered as Field Examinations 

 such as F.E. No. 6 (1960). Where the boat 

 sheet is clearly legible and soundings have 

 been corrected to show true depths, a smooth 

 plot of the survey is often unnecessary and 

 is not required. The survey sheet is usually 

 cut or folded and filed with the descriptive 

 report after verification and review. 



6-79 Shipment to Washington Office. — 



A complete smooth sheet shall be shipped to 

 the Washington Office only in special plastic 

 containers supplied for this purpose. Card- 

 board or thin metal tubes are not satisfac- 

 tory containers and are often badly damaged 

 in transit. Shipping tubes will be furnished 

 on requision to the Washington Office. 



All records shall be forwarded by regis- 

 tered parcel post or express (see 7-24). Boat 

 sheets should be sent separately and in sep- 

 arate mails. The smooth sheet should never 

 be rolled to a diameter less than four inches. 



Verification of Surveys 



6-80 Office inspection and registration. 



— On receipt in the Washington Office the 

 smooth sheet is inspected by the Chief, Hy- 

 drographic Section, Chart Division and Chief, 

 Hydrography Branch, Coastal Surveys Di- 

 vision. It is registered and diagrammed on 

 the Nautical Chart Standards and Hydro- 

 graphic Survey Index Charts. It may be im- 

 mediately assigned for preliminary applica- 

 tion to charts which are currently being 

 revised or constructed. It is preferably first 

 assigned for preliminary or complete verifi- 

 cation, depending on the controlling factors 

 of priority, time, and the nature of the 

 hydrography. 



6-81 Vertical datum verified. — Before the 

 smooth sheet is verified the sounding records 

 are referred to the Tides and Currents Di- 

 vision for verification of the plane of ref- 

 erence for each tide station used in the re- 

 duction of soundings. If a preliminary 

 datum used in the reduction of soundings 

 differs more than 0.3 foot from the final 

 adopted datum, then values in the sounding 

 records shall be revised. A spot check of the 

 reducers used for each day's soundings is 

 also made. Verification and approval of the 

 plane of reference shall be recorded in a 

 stamp on the inside of the back cover of 

 each volume of the sounding records. 



Form 712, Tide Note for Hydrographic 

 Sheet, shall be completed and forwarded to 

 the Hydrographic Section for insertion in 

 the descriptive report (see 7-13d). 



6-82 Purpose of verification. — The nomi- 

 nal duty of the verifier is to carefully check 

 unverified data penciled on the smooth sheet, 

 correct any errors in the original plotting, 

 and ink the soundings and other hydro- 

 graphic data in conformance with standard 

 cartographic practices. The work of the 

 verifier extends beyond correcting obvious 

 errors and providing a complete permanent 

 record of the survey. He also has the re- 

 sponsibility of detecting and correcting er- 

 rors of a less evident nature in the plotting, 

 reduction or interpretation of the data which 



