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HYDROGRAPHIC MANUAL 



shall be maintained except in areas where 

 slight distortions are advisable to prevent 

 misinterpretation as zero soundings. 



When a section of the shoreline is revised 

 during hydrographic operations and super- 

 sedes a prior survey for reasons of natural 

 change or error, that section shall be inked 

 in red (see 4-16 and 5-67). This does not 

 apply to shoreline revisions to be incor- 

 porated in a contemporary photogrammetric 

 survey. The revisions are usually trans- 

 ferred from the boat sheet or auxiliary 

 planetable sheet which does not warrant 

 registry as a topographic survey. The re- 

 vised shoreline shall be a continuous line 0.4 

 mm wide if it was surveyed in accordance 

 with topographic standards; otherwise it 

 shall be shown by a dashed line. 



The shoreline shall generally be omitted 

 beyond the limits of the survey. Although 

 extended or flanking shorelines are some- 

 times desirable for reference, excessive work 

 on a large amount of unrelated shoreline is 

 unwarranted. 



6-28 Low-water line. — The low-water line 



is the curve of zero depth and is best de- 

 lineated by soundings in its vicinity (see 

 5-17). The low-water line shall always be 

 left in pencil on the smooth sheet until the 

 survey has been verified in the Washington 

 Office. 



After verification the low-water line as 

 represented by zero soundings is inked with 

 a continuous orange line. Where it is posi- 

 tioned by estimated distances from a launch, 

 it is shown by a dashed orange line. In the 

 absence of hydrographic information, the 

 low-water line transferred in pencil from the 

 photogrammetric survey is inked as a black 

 dotted line. 



6-29 Limit lines. — Dashed lines on pho- 

 togrammetric manuscripts used to delineate 

 approximate limits of channels, shoals, kelp, 

 or foul areas shall not be transferred to the 

 smooth sheet. These lines are intended to 

 serve as guides to the hydrographer and are 

 usually superseded by hydrographic informa- 

 tion (see 5-14). After the hydrography is 

 smooth plotted, the limit lines not super- 

 seded by hydrographic information shall be 



Avoid displacement or generalization 

 of shoreline when transferred from the 

 topographic survey- 



Shoreline shown on smooth sheet without 

 obscuring positions of control stations. 



Figure 80. — Correct and incorrect shoreline delineations on a smooth sheet. 



