12 NAUTICAL CHART MANUAL 



SCALES (Figs. 6, 7, 8) 



A chart constructed at a scale of 1 : 80,000 or larger should have on it two sets of graphic 

 scales. Each set consists of a scale of nautical miles and a scale of yards. One of the sets 

 should be at the top of the chart and the other at the bottom, and on opposite sides if possible. 

 On Intracoastal Waterway Charts a graphic scale of statute miles is added between these for 

 nautical miles and yards. 



A complete border scale should be placed on all conventional charts at the scale of 1 : 50,000 

 and smaller. 



The type of projection, scale of chart, and the latitude at which the scale was computed, 

 shall be given in the title of all charts. The scale at the middle latitude of the series shall be 

 given when the projection was computed on a latitude falling off the chart. 



BORDERS 



The border of a chart is either a neatline or a border scale defining the limits of the area 

 charted. Outside the neathnes, and separated by a space in which the projection numbers 

 are placed, are two parallel lines, one fine and one heavy, drawn close together. See Figure 4 

 in the Appendix. 



On an average chart, the degree numbers shall appear at least twice for latitude and twice 

 for longitude. The border subdivisions on charts whose scale is larger than 1 : 50,000 shall be 

 shown at the border by lines 2 mm. long outside the neatlines. Additional subdivisions of 

 latitude and longitude are to be added in accordance with Figure 4 in the Appendix. 



When the projection is skewed (Fig. 4A), one minute of latitude and of longitude shall 

 be subdivided into seconds in at least one place within each chart panel, preferably on land 

 area clear of pertinent detail. The numerals and ticks may be placed on either side of the 

 projection lines. Subdivision intervals shall be in accordance with those shown in Figure 4. 



DIMENSIONS OF THE EARTH (CLARKE'S SPHEROID OF 1866) 

 AND UNITS OF LENGTH 



The following values are used by the Coast and Geodetic Survey in its computations. 

 They were taken from Special Pubhcation No. 138. (See also Figures 29-34, 37) 



Equatorial radius 6 378 206.4 meters 



Polar semi-axis 6 356 583.8 meters 



1 kilometer 0.621 370 statute mile 



0.539 593 nautical mile 

 1 meter 0.000 621 370 statute mile 



0.000 539 593 nautical mile 



39.37 inches 



3.280 833 3 feet 

 1 statute mile 1 609.35 meters 



1.609 35 kilometers 



0.868 393 nautical mile 



5 280 feet 

 1 foot 0.304 800 61 meter 



NAUTICAL MILE (INTERNATIONAL) (Figs. 33, 34) 



To conform to international usage in computing distances and speeds, the value of 1 852.0 

 meters or 6 076.115 49 feet (approximately) shall be used for a nautical mile. 



