68 THE NAVY OCEANOGRAPHIC OPERATIONS PROGRAM 



purpose charts. In this category are charts which have been 

 constructed on special projections to facilitate great circle 

 tracking and quick visual determination of azimuth and great 

 circle distances, position plotting sheets for all world areas, 

 maneuvering boards and radar plotting sheets, star charts, time 

 zone charts, world charts, coordinated series of charts for com- 

 mand and control purposes, small boat charts, strategic planning 

 and plotting charts, and charts designed expressly for hydrographic 

 and oceanographic survey plotting. 



The Navy, through its automated cartographic production 

 system, has pioneered in the mass production of most of the 

 aforementioned charts. Computer programs have been developed 

 to permit rapid and precise construction of such charts on any of 

 over thirty different projections, each possessing unique qualities 

 for various needs. Charts on the azimuthal equidistant projection, 

 for example, permit depiction of the entire earth on a single sheet, 

 and are particularly useful in communications studies. Thus, 

 if a chart is constructed with a selected geographic coordinate or 

 city at its center, the great circle or true distances and azimuths 

 from this point, to any other point on the earth's surface, may be 

 rapidly determined by inspection. The Oceanographic Office 

 has produced over twenty such charts, and more are programmed. 



Great circle tracking charts comprise a second important group 

 of special purpose charts. These charts are constructed on the 

 gnomonic projection and permit rapid determination of the great 

 circle track or shortest route between any two points on a given 

 chart. Although originally designed about 1884 to enable navi- 

 gators to plan their routes, the charts have been found invaluable 

 tools in tracking ships and other craft. 



A total of 72 great circle tracking charts are on issue and 

 available to the government and private individuals and insti- 

 tutions. In addition to providing a quick tracking capability, 

 the charts show important reference detail such as coastline, 

 principal islands, cities, navigable rivers, bathymetric curves at 

 1000 fathom intervals, important depths, names of principal 

 bathymetric features, and other specialized information of value 

 to either operations or planning. 



Perhaps the largest group of special purpose charts in number 

 is the precise positioning sheet. Such sheets are specially con- 



