7841 HYDROGRAPHIC MANUAL PaGE 740 



The smootli-sheet plotter shall compare the plotted information with that shown 

 on the charts and with that given in the most recent edition of the Light List published 

 by the United States Coast Guard, and any material disagreement as to position or 

 characteristics shall be noted in the Descriptive Report (see 842P). The positions of 

 all fixed aids shall also be reported on Form 507. (See also 383.) 



Hydrographic survey parties are required to obtain the depths at all aids to naviga- 

 tion located in the water area, and these shall be shown in pencil similar to other 

 soundings. 



Where items 7841 to 7847 inclusive specify that certain data are to be left in pencil 

 by the plotter, they shall be inked in black after verification at the Washington Office. 



7841. Fixed Aids to Navigation 



Fixed aids fall into two classes, lighted and unlighted, and their correct respective 

 designations are "lights" and "beacons." 



In the case of lights, the light sector shall be shown graphically and the limit of 

 visibility in miles given, in pencil, if these have been determined during the hydro- 

 graphic survey. The characteristics of the lights need not be shown on the smooth 

 sheet. 



All fixed aids that have been rebuilt since the date of a previous determination of 

 position, whether or not they are reported to have been rebuilt in the same position, 

 are relocated by the survey party, but must not be referred to as recovered stations. 

 The earlier determinations are lost stations and no reference to them shall be made on 

 the smooth sheet. (See also 3831.) 



Where an abandoned light structure is still prominent, its position shall be deter- 

 mined. If it is not located by triangulation, nor used as a control station, it shall be 

 shown on the smooth sheet as a landmark (see 7844). 



7842. Floating Aids to Navigation 



Floating aids to navigation are divided into two classes, buoys and lightships. 

 Their positions are usually determined by the hydrographic party, either by three-point 

 fixes or by cuts (see 3832). Standard symbols are used to represent them on the smooth 

 sheet (see 784). The small dot at the lower end of the buoy symbol or the small circle 

 at the bottom of the lightship symbol indicates the position of the aid. The type of 

 buoy should be indicated by the correct symbol, and the number of masts on a light- 

 ship should also be indicated by the symbol used. 



The symbol for a buoy is an elongated diamond shape with its longer axis 2.7 mm 

 in length and its shorter axis 1.2 mm. The dot is 0.8 mm distant from the shape on 

 line with the long axis. 



Buoy symbols are best made by means of a celluloid template cut to a slightly 

 larger size than the above dimensions so that when the pencil outline is drawn on the 

 sheet, it will be of the required size. (See fig. 153.) 



7843. Names of Aids to Navigation 



Care must be taken that the aids to navigation are identified by their correct names, 

 which in all cases shall be assumed to be those given in the latest edition of the Light 

 List. (See fig. 169.) 



(a) The Light List names of all aids to navigation must be shown on the smooth 

 sheet. If the aid has a station name which is identical with that given in the Light 



