1. genp:ral requirements 



be continually monitored, and if lanes are 

 gained or lost appropriate corrections ap- 

 plied. The equipment should be reset at a 

 known point as soon as practicable. The 

 maximum usable range of Ray.dist has not 

 been determined, but usable signals have 

 been received at distances in excess of 250 

 miles. 



1-20 Plotting control. — When muslin- 

 mounted boat sheet paper is used, there is 

 always a possibility that the projection will 

 soon be distorted to some extent by changing 

 atmospheric conditions. If electronic control 

 is to be used, the distance arcs should be 

 plotted as soon as possible after the projection 

 has been checked (see 5-11). When the boat- 

 smooth sheet procedure is to be used, it is 

 essential that the amount of distortion be 

 determined and proper corrections applied to 

 measured distances before the arcs are drawn. 

 Three positions on three well-distributed arcs 

 shall be computed and plotted and interme- 

 diate points plotted by mechanical subdivi- 

 sion or by means of a template. The arcs 

 are then drawn in colored ink with a beam 

 compass, or along the edges of plastic arcs 

 of appropriate radius. When aluminum- 

 mounted paper is used, there should be little 

 or no distortion and rapid plotting of arcs is 

 less urgent. Distance units (miles, lanes, or 

 microseconds) shall be numbered in match- 

 ing colors on the arcs, but should be near 

 the ends of the arcs or in areas where no 

 soundings will be plotted. 



The positions of stations to be used for 

 visual control of hydrography shall be plot- 

 ted before the projection is inked. Triangu- 

 lation stations shall be plotted by dms and 

 dps and checked. Stations located in the 

 field on photogrammetric manuscripts shall 

 be pricked through to the boat sheet after 

 correct registration of the projections has 

 been made. If the stations are shown on 

 the blueline prints of the manuscripts, they 

 shall be transferred by burnishing, adjusting 

 the projections as necessary to compen.sate 

 for distortion. Stations located by plane- 

 table surveys are transferred by tracing 

 paper and similar adjustments made. All 



such transfers shall be verified before the 

 station symbols are inked. 



1-21 Station symbols and names. — Each 

 station used for control of the hydrography 

 shall be identified on the boat sheet by its 

 appropriate symbol and name, both inked in 

 the color specified. The actual station point 

 is a fine needle hole, the edges of which are 

 blackened by carefully rotating a sharp, hard 

 pencil point in the hole. The symbols and 

 colors shall be according to the following 

 scheme and Figure 79: 



(a) Triangulation and traverse stations 

 shall be identified by red equilateral tri- 

 angles, 4.5 mm. on a side, symmetrically 

 placed around the station point with the 

 base of the triangle parallel to a line of 

 latitude. 



(b) Topographic stations, whether located 

 by planetable or air photographic surveys, 

 shall be identified by red circles 3 mm. in 

 diameter. 



(c) Hydrographic stations (stations lo- 

 cated by sextant fixes or cuts) shall be identi- 

 fied by blue circles 3 mm. in diameter. 



(d) Supplemental stations which have 

 been spotted by the hydrographic party from 

 details of the photographs or air photo- 

 graphic survey shall be identified by green 

 circles 3 mm. in diameter. 



(e) Electronic control stations shall be 

 identified by the symbol appropriate for the 

 method of location and a circle about 5 mm. 

 in diameter in a color corresponding to the 

 distance circles drawn from it. 



All station names shall be inked on the 

 boat sheet in vertical letters with the over- 

 all height of the upper case letters not to 

 exceed 3 mm. and in the same color as the 

 symbol the name identifies. Names should 

 never be placed in water areas. 



1-22 Transfer of topographic detail. — 



The shoreline and alongshore detail shall 

 be carefully transferred to the boat sheet. 

 After the transfer has been verified, the 

 shoreline shall be inked with a continuous 

 solid black line about 0.4 mm. wide. The 

 rocks, limits of kelp or foul areas, and simi- 

 lar detail lying outside the highwater line 



