Page 857 miscellaneous 9345 



(6) Where the position of what is presumably the same rock differs on the new and the prior 

 survey, the new position should be accepted as correct. 



(c) Where an adequate examination, made by the new hydrographic or topographic survey in the 

 vicinity of a rock or rocks, fails to disclose the existence as shown on the prior survey, the recom- 

 mendation made by the hydrographer regarding its disposition, should be followed (see 842L). 



General statements in a Descriptive Report, particularly of a topographic survey, that certain rocks 

 on old surveys could not be found should be accepted only as proof that such rocks are not bare rocks. 

 They should be transferred either as rocks awash or as sunken rocks, depending on the circumstances 

 in each particular case. 



(d) Rocks originating with a prior topographic survey and not disproved, that are to be carried 

 forward should be shown in color on both the new topographic and the new hydrographic survey. 

 Rocks that are to be carried forward from a prior hydrographic survey should be shown on the new 

 hydrographic survey only. 



(e) Bare rocks on a prior topographic or hydrographic survey, that are not shown or disproved 

 on the new hydrographic or topographic survey should be carried forward as rocks awash. 



(/) Rocks aivash on a prior survey that are shown as sunken rocks on the new survey should be 

 considered as rocks awash unless there is information on the new survey to show that the rock was 

 not visible at low tide. In such cases the rock awash symbol should be shown in black ink on the 

 new hydrographic survey and a note made in the Sounding Record. 



ig) Sunken rocks on prior surveys, if not disproved by the new survey, should be carried forward 

 as such. 



(h) In general, the delineation inside the low-ivater line should be accepted as correct on the new 

 survey, except that isolated rocks awash shown on a prior topographic survey, that are not located or 

 disproved on the new survey, should be carried forward in color, 



9345. Comparison With the Chart 



A comparison should be made with the largest-scale chart of the area, using one 

 with the most recent print date (1127), for matters not already considered. 



a. Hydrography.— Most of the charted data will already have been considered in 

 the comparison with prior surveys. Attention need be given only to those data trace- 

 able to chart letters, field examinations, U. S. Coast Guard and U. S. Hydrographic 

 Office Notices to Mariners, U. S. Corps of Engineers blueprints, or other sources. In 

 general, comparison with surveys of other organizations should be restricted to charted 

 information only. Only in exceptional cases is information from such sources actually 

 carried forward on the new survey. 



b. Controlling depths. — The controlling depth notes, which are charted in channels 

 in which no soundings are charted, should be compared with the new survey. These 

 notes appear in the form "24 feet June 1941". The notes are usually based on data 

 furnished by the United States Corps of Engineers. It should be bonie in mind that 

 the notes are frequently based on data subsequent to the date of the survey and there- 

 fore supersede the survey information. 



c. Aids to navigation. — The aids on the new survey should be compared with those 

 on the latest aid proof, to see whether the positions and characteristics are substantially 

 the same. They should be examined to see whether they satisfactorily mark the 

 features or serve the purpose for which they are intended. 



9346. Descriptive Report 



As the review progresses, each statement in the Descriptive Report and in the 

 verifier's report should be considered and each paragraph should be checkmarked in 

 red ink when disposed of. Where additional evidence has altered positive statements in 

 the Descriptive Report, a marginal notation citing the disposition and authority 

 should be lettered in red ink. Notations made in the Descriptive Report or the written 



465382—44 56 



