HYDROGRAPHY 55 



When there are channel ranges, a line of soundings on the range should be selected. This 

 does not apply to areas in dredged channels where depths are indicated by a note. 



If the application of a recent survey to a chart reveals conditions so changed that satis- 

 factory jimctions cannot be made with the hydrography of former surveys, a blank space is 

 left beyond the limits of the more recent survey and a note is added: "Hydrography to (east- 

 ward) from surveys of 1934." 



On small-scale charts, soundings within a group of rocks or coral heads through which 

 there is no well defined channel should be omitted. 



Sourdmgs should be shown in slips and aroimd piers if space permits. Care must be 

 taken to select soundings far enough off the faces of piers to indicate depths at the bilge and 

 and keel lines of vessels which will probably use such piers. In new docks or sUps where main- 

 tenance of depths is questionable, legends with dates should be used if space permits. 



A shoal soimding on an isolated rock should have the abbreviation "Rk" placed near it. 

 (See 0-5a.) 



SELECTION OF SOUNDINGS WITHIN COMPASS ROSES 



In an area covered by a compass rose, care must be exercised to avoid selecting soimdings 

 or bottom characteristics which may fall on the numerals marking the graduations. Where a 

 shoal sounding falls on one of the num.erals, it usually will be necessary to move the rose. 

 The selection of soimdings or bottom characteristics which fall on a limb of the compass should 

 be avoided. The foregoing apphes to all charts, whether the rose is currently printed in 

 magenta, red, or black. 



UNDERLINED SOUNDINGS (Q-2) 



Soimdings selected from blueprints should be imderlined on the prints as an aid to the 

 reviewer. 



NO-BOTTOM SOUNDINGS (Q-2) 



No-bottom soundings are shown under a bar and smaU dot, thus: 22i» ^^^ their use 

 should be avoided whenever possible. 



STREAM DEPTHS (Q-Qa) 



The shoreline of narrow streams may be broken to show soimdings when necessary. Along 

 narrow streams the controlling depths from Engineers' reports should be shown at the places 

 indicated in the report. Leaders should not be used to show the location of soundings. 



692-834 O - 64 - 5 



