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HYDROGRAPHIC MANUAL 



triangulation stations plotted by geographic 

 positions or photo-hydro signals located on 

 adjacent advance or final manuscripts. See 

 Photogrammetry Instruction 45, Revision 1, 

 15 March 1954. 



Shoreline and offshore detail shall be trans- 

 ferred to the boat sheet and inked, but a 

 preliminary manuscript shall not be used to 

 transfer any information to a s-mooth sheet 

 (see 6-26). 



A preliminary manuscript must be recom- 

 piled after control has been identified. Ob- 

 viously this is inefficient and Chiefs of Party 

 should establish and identify control far 

 enough in advance of hydrographic work to 

 avoid the necessity of using preliminary 

 manuscripts. 



4-14 Use of incomplete manuscripts. — 



An incomplete manuscript is a final photo- 

 grammetric plot based on field identified 

 control but with insufficient field inspection 

 of topographic detail particularly along the 

 shore. The location of photo-hydro signals 

 on this class of manuscript is final and such 

 signals may be transferred directly to the 

 smooth sheet. Since the shoreline and along- 

 shore detail or sections thereof are compiled 

 largely from office interpretation of the photo- 

 graphs, it is expected that some errors will 

 occur. These errors will be corrected in the 

 office on the basis of the field inspection 

 reports submitted by the hydrographic 

 party (see 4-16 and 4-17). 



4-15 Use of advance manuscripts. — No 



additional office work will be done on these 

 manuscripts unless errors are found during 

 the hydrographic surveys. The locations of 

 photo-hydro signals on this class of manu- 

 script are final. The shoreline and offshore 

 detail shall be verified or corrected as speci- 

 fied in 4-16 and 4-17. 



4-16 Shoreline inspection. — Where pre- 

 liminary and incomplete manuscripts have 

 been compiled from an office interpretation of 

 the photographs and no errors are found in 

 the shorline and alongshore detail during the 

 hydrographic survey, no field inspection notes 

 are required. Where they are incorrect, 

 sufficient notes shall be made on the field 



photographs and paper prints of the manu- 

 scripts to enable the compiler to map the 

 shoreline correctly. When changes are nu- 

 merous, the manuscript will be corrected and 

 a new blueline copy will be furnished for 

 application of shoreline to the smooth sheet 

 (see 6-26). 



Instructions for field inspection of shore- 

 line are contained in Photogrammetric In- 

 struction 49 dated 18 March 1944. In Alaska 

 the foul line symbol is frequently used to 

 outline shoal and rocky areas in which detail 

 is not clearly visible on the photographs. 

 Where additional detail is required in any 

 such area, the information shall be shown 

 as above or on the boat sheet. In Alaska it 

 is not intended that all shoreline be inspected 

 in detail, but rather that short stretches of 

 typical shoreline be field inspected at con- 

 venient and practicable landing places. 



Where appreciable accretion or erosion 

 has taken place since the date of the photo- 

 graphs or field inspection, the photogram- 

 metric manuscript may be corrected by 

 various methods. When planetable methods 

 are being used to locate supplemental control, 

 the shoreline shall be corrected on the 

 graphic control sheet. In other cases the 

 paper print of the manuscript may be used 

 if excessive distortion is not a factor. A sec- 

 tion of shoreline may be transferred to an 

 aluminum-mounted sheet without projection 

 and the new shoreline corrected. The black- 

 line impression may also be used as a topo- 

 graphic sheet and corrections surveyed di- 

 rectly thereon. A photograph may be used 

 in the same way, however, this method is 

 complicated for use except by experienced 

 photogrammetrists. 



The shoreline corrections can be deter- 

 mined by sextant fixes when planetable 

 methods are impracticable. As a last choice, 

 the corrections can be made by sketching the 

 shoreline by estimated distances from fixed 

 positions along the shore as hydrography 

 progresses. 



Where the shoreline has been revised by 

 standard topographic methods, or methods 

 of equal accuracy, the revised shoreline shall 



