Nautical charts can pinpoint your location using lines of latitude and longitude. The latitude scale runs vertically along both sides of the chart indicating North and South with the equator as the zero point; the longitude scale runs horizontally on the top and bottom of the chart, and indicates East and West with the Prime Meridian as the zero point.
The chart number is the number assigned to the chart located in the lower right hand corner (11415). Use this to locate charts online and to make purchases. The edition number is located in the lower left hand corner and indicates when the chart was last updated (not shown). Corrections published in the Notice to Mariners that occur after the publish date will need to be entered by hand.
