843 HYDROGRAPHIC MANUAL PaGE 790 



Describe all useful ranges, bearings, and other marks for clearing dangers or ))assing close by or 

 over them and the best courses across bars in accordance with 356. 



Describe the prevailing weather in the area for the period of the survey if it is a little-known area; 

 otherwise, describe only weather conditions differing from normal. 



Describe the currents encountered in the area (the average and maximum experienced) and give 

 their directions, and state the basis of the information if current observations were not made. 



Mention any wrecks or obstructions which are dangerous to navigation (see 365). 



P. Aids to navigation. — The positions of fixed aids to navigation shall be reported on Form 567 in 

 accordance with 8532. A reference to this report shall be made. 



List all floating aids to navigation located, using the exact nomenclature given in the Light List, 

 and give the latitude and longitude of each, the depth of water at each, the position number or numbers 

 of the location data, and the date of location. (See 784 and 8531.) 



Mention specifically any aids to navigation whose positions or characteristics differ materially 

 from those on the charts or in the most recent edition of the Light List (see 784). 



A reference shall be included to any report made during the field season directed to the United 

 States Coast Guard relative to aids to navigation. (See 3832 and 853.) 



List the azimuths of all ranges maintained for navigation that were determined in connection with 

 the survey. (See 3833.) 



List all unofficial aids to navigation stating their purpose, whether maintained and by whom, 

 and whether such maintenance is seasonal or not, if this is known. Give the position and a description 

 of each aid, and the date of establishment if known. (See 3834.) 



List the overhead clearances of all bridges and telephone or telegraph lines over waterways (see 

 3836). State whether each was measured, estimated, or obtained from the "List of Bridges over the 

 Navigable Waters of the United States" published by the United States Corps of Engineers. Discuss 

 any discrepancies between the field data and that found in the above publication. 



Mention any submarine cables and ferry routes within the area and give the positions of their 

 termini (see 7847 and 7867). 



Q. Landmarks for charts. — Data relative to landmarks for charts shall be submitted on Form 567 

 on an area basis. (See 155.) A reference to this report shall be made here, with a list of the recom- 

 mended landmarks within the limit of the survey, but no other data are necessary. (See 8534.) 



R. Geographic names.- — ^A special report on geographic names is required (see 163 and 856) to 

 which reference shall be made under this heading. The reports required on this subject are fully 

 described in section 16. If a special report has been recently submitted or will be submitted it should 

 not be duplicated here, but it should be supplemented by (1) any additional information which has 

 been discovered, and (2) recommendations for naming important previously unnamed features. 

 (See 164.) 



If the one survey constitutes the entire season's work, all of the information required on geographic 

 names may be included here rather than in a special report. (See also 8433.) 



Any geographic names which are found to apply to areas of indefinite extent should be discussed 

 under this heading and not shown on the smooth sheet. 



S. Silted areas. — Where silted areas are detected by the use of an echo-sounding instrument, a full 

 discussion shall be included as to the frequency and size of the areas and their apparent thickness. 

 (See 7831.) 



T. By-product information. — Give any information of scientific or practical value resulting from 

 the survey or from special investigation or observations made. If special reports of this nature have 

 been submitted they sh6uld be referred to under this heading by title and author. (See 1134 and 

 8585.) 



U.~Y. Miscellaneous. — Include under these letters other information which should be included in 

 the Descriptive Report in special cases. (See for example 8434.) 



Z. Tabulation of applicable data. — Include a complete list of data connected with the hydrographic 

 survey, including all forms, records, and special reports which are not made a part of the Descriptive 

 Report and excluding, of course. Sounding Records and Bomb Records. Give the date each was for- 

 warded to the Washington Office. (See sections 83 and 85.) 



843. Separates Following Text 



Various tabulations and kinds of information are required on separate sheets of 

 paper inserted in the Descriptive Report. Each of these that is apphcable shall be 

 furnished, inserted in the order in which it is described in the following items. 



