212 



HYDROGRAPHIC MANUAL 



cables shall be shown by black dashed lines 

 with appropriate notes. 



6—38 Fixed aids to navigation. — All fixed 

 aids to navigation within the area of the 

 survey shall be shown on the smooth sheet. 

 Most fixed aids, lights and daybeacons, are 

 located by triangulation or on topographic 

 surveys and are used as control stations for 

 hydrographic surveys (see 1-50). Positions 

 of some aids are established during the sur- 

 vey and may include aids rebuilt subsequent 

 to the topographic survey. A separate re- 

 port on fixed aids is required on Form 567 

 (see 7-22). 



Where the fixed aids are used to control 

 hydrography, symbols appropriate to the 

 method of location shall be used, otherwise 

 nautical chart symbols shall be used (Fig. 

 79), except that all fixed aids located by 

 triangulation shall be shown by the triangu- 

 lation symbol. The name or designation of 

 each shall be shown as illustrated. 



A permanent type aid which has been 

 established by an individual or firm, whether 

 or not it is maintained, shall be shown by 

 the landmark symbol, if not used as a con- 

 trol signal, and shall be described as a 

 "marker." 



Private semi-permanent aids such as 

 stakes, with or without baskets or kegs, 

 along a shallow channel shall be a 1 mm 

 circle and described as "stake." 



If an abandoned light structure is still 

 prominent and is not used as a control sta- 

 tion it shall be shown as a landmark. 



6-39 Visible obstructions. — Visible ob- 

 structions in the water area, such as wrecks, 

 piles, breakwaters, groins, fences, duck 

 blinds, and fish houses, are located on topo- 

 graphic surveys and transferred to the 

 smooth sheet in pencil and are subject to 

 confirmation by the hydrographic survey. 

 They are shown by distinctive symbols (Fig. 

 79) or by 1 mm circles or dashed lines ac- 

 companied by a description. This informa- 

 tion is shown in pencil by the smooth plotter 

 and is inked after office verification. 



6-40 Marine vegetation. — The limits of 

 kelp beds or other types of marine vegeta- 



tion transferred to the smooth sheet from 

 photogrammetric surveys are subject to re- 

 vision by the hydrographic survey and 

 should not be inked on the smooth sheet. 

 Extensive areas of marine vegetation shall 

 be delineated by dashed pencil lines which 

 shall be inked black after office verification, 

 unless a line overlaps plotted hydrography. 

 In this instance the line shall be omitted and 

 the appropriate symbol used to the inshore 

 end of the sounding lines where a legend can 

 be used. Detached small areas of kelp shall 

 be shown by symbol (Fig. 79). Grassy 

 areas shall be shown by the note "grass" or 

 its abbreviation "Grs." 



Masses of free unattached kelp or other 

 floating vegetation noted by the hydrog- 

 rapher shall not be shown on the smooth 

 sheet. Marine growth recorded on the fatho- 

 gram shall not be shown by symbol or legend 

 unless it is reported by the hydrographer to 

 surface or be visible at the sounding datum. 



6-41 Descriptive notes. — A variety of 

 descriptive notes is required on the survey 

 sheet for purposes of identification, refer- 

 ence, and completeness of the survey data 

 (Fig. 82). They shall be in parentheses 

 when preceded by a name or primary desig- 

 nation. The notes shall be short, sometimes 

 abbreviated, but always clear as to required 

 information. The lettering should usually be 

 freehand (see 6-13) and not larger than 1.8 

 mm for most notes, except at landmarks 

 where the primary description shall be in 

 capital letters 2.2 mm high. Other notes 

 should be in lower-case letters. Differentia- 

 tion for elevated or submerged features and 

 the placement of lettering are discussed in 

 Sections 6-14, 6-15. It is important that 

 each control station which could be readily 

 recovered or identified for use on future sur- 

 veys, shall be described in a penciled note on 

 the smooth sheet. When Form No. 524 is 

 submitted for an unmarked station, the ab- 

 breviated notation for "described," "(d)," 

 shall be placed by the station name. It is 

 very important that stations in the water 

 shall be described (see 5-10). To avoid any 

 possible misinterpretation as bare rocks, dots 



