38 HYDROGRAPHIC MANUAL PaGE 296 



38. CONTEMPORARY OPERATIONS 



In conjunction with each hydrographic survey certain contemporary operations 

 must be performed and certain data obtained and noted which are not strictly related 

 to sounding. Those which are the responsibility of the Chief of Party and the survey 

 party generally, but which may not necessarily be performed by the hydrographic 

 party, have been described in chapter 1 — but those which should be performed by each 

 hydrographic party are described in this section. 



381. Shoreline by Hydrographer 



In conjunction with a survey of the inshore waters adjacent to the shoreline it is 

 incumbent on the hydrographer to see that the necessary shoreline information to 

 accompany the hydrographic survey is available. The high- water line and the topog- 

 raphy offshore from it are the most important parts of the topographic information 

 obtained during a hydrographic survey. 



The hydrographic party shall verify the correctness of the topographic detail 

 falling within the limits of the hydrographic survey. Wlien both the topographic and 

 the hydrographic survey are made in the same season imder the direction of the same 

 Chief of Party, it shall be his duty to see that any discrepancies between the two 

 surveys are investigated in the field and that information common to both is 

 identical. 



\^Tiere the contemporary topographic survey has been made in a previous season 

 or under a different Chief of Party, the hydrographic party will be responsible for the 

 revision of the topography if any changes have occurred or if any discrepancies are 

 found therein. 



Complete notes relative to topographic information obtained by the hydrographic 

 party and all three-point fixes, sextant cuts, and measured or estimated distances shall 

 be recorded in the Sounding Record. The Descriptive Report for the hydrographic 

 survey shall explain in considerable detail the revision of any shoreline, the methods 

 used by the hydrographer to locate it, and the apparent reason necessitating the change. 

 (See also 3244.) 



3811. Shoreline Revision 



Where there has been a contemporary topographic survey either by planetable or 

 from air photographs, the results of which are available prior to the hydrographic 

 survey, the shoreline and all topographic details offshore therefrom shall be transferred 

 accurately to the boat sheet in order that the hydrographer may verify the complete- 

 ness and accuracy of these data during his sounding operations. Any shoreline data 

 which are found to be inaccurate, or where appreciable accretion or erosion has taken 

 place, shall be corrected and shown on the boat sheet by a broken or solid red line, de- 

 pending on the accuracy of location (see 753), accompanied by appropriate notations 

 of the general method used to determine the position of the revised shoreline. 



3812. Sketched Shoreline 



Wliere no topographic survey of the area is available and a contemporary one is not 

 contemplated or where the only information available is from an entirely inadequate 

 reconnaissance survey, the hydrographer should locate by carefully estimated or 

 measured distances all the important features of the shoreline in connection with his 

 hydrography. This may be done from a series of three-point fixes taken close to the 



