Page 745 the smooth sheet 7869 



sunken, the former applying where any portion of the hull is above the sounding datum, 

 wliile the latter applies to those vdth less than 10 fathoms over them or where the masts 

 only are visible. The topographer, presumably, will have located all stranded wrecks, 

 and these will be transferred from the topographic sheet to the smooth sheet along with 

 the other topographic information. Sunken wrecks are located by the hydrographic 

 party and their positions must be plotted from the data in the Sounding Records. It 

 should be noted that the symbol for a stranded wreck differs from that for a sunken 

 wreck, and that where masts are visible in the latter case, the notation "masts" must 

 be appended to the symbol. 



A special symbol is provided for use in showing the depth by which a wreck or 

 other obstruction has been cleared by the wire drag. 



Where there are a number of wrecks, or an amount of wreckage, so extensive that 

 the individual items were not located, the outer limit of the dangerous area shall be 

 indicated by a dotted line within which the word "wreckage" is shown. 



7869. Obstructions 



A variety of obstructions which may be dangerous to navigation is encountered in 

 hydrographic surveys, all of which must be shown on the smooth sheet. If the obstruc- 

 tion has not been cleared by the wire drag, it is indicated by the least depth obtained by 

 other methods, surrounded by a dotted circle, and accompanied by the word "obstruc- 

 tion" or its abbreviation. If the obstruction has been cleared by the wire drag, a spe- 

 cial symbol is provided which shall be used to indicate the safe depth of water over the 

 obstruction (see part "O", Symbols and Abbreviations chart, fig. 189, part IX). 



787. Geographic Names 

 7871. Authority of the Smooth Sheet 



The hydrographic survey and, therefore, the smooth sheet shall be the authority for 

 all geographic names of hydrographic features, such as channels, sloughs, rivers, inlets, 

 reefs, rocks, shoals, and of topographic features offshore from the high-water line, such 

 as small rocks and islets. Even if the topographer does obtain and verify a portion of 

 these names, the hydrographer is responsible for their correctness and their correct 

 placement on the smooth sheet. In addition to the above names, the names of some of 

 the more prominent topographic features should be added to assist in correlating the 

 hydrographic survey to the land features. (See also section 16.) 



Although not all geographic names may be charted, it is desirable that all features 

 for which there are local names be named on the smooth sheet. These should be distinct 

 names applicable to definite places or areas. Where names are indefinitely applied, it 

 is best not to show them on the smooth sheet, but they should be mentioned in the 

 Descriptive Report. It is incumbent on the smooth-sheet plotter to take extreme care 

 that the names are spelled correctly and that they are applied to the correct features. 



7872. Placement of Names 



Geographic names should not be added to the smooth sheet until after the posi- 

 tions and soundings have been plotted. They should be placed so as to indicate 

 clearly and without ambiguity the features designated. Where it is impracticable to 

 place the names closely adjacent to the features, they may be placed some little distance 

 away and connected to the respective features by leaders or arrows. 



