Session IV Measuring Latitude and Longitude
General Rules Set your GPS to read DEGREES – MINTUES - SECONDS On a chart, LAT/LON is read in: Degrees Minutes Seconds or Tenth’s of a Minute Set your GPS to read DEGREES – MINTUES - SECONDS
Rules for reading LAT/LON On a Nautical Chart: Read the Degrees from the LAT/LON scales. Read the Minutes from the LAT/LON scales. Measure the Seconds or Tenth’s of a Minute.
Measuring the Seconds of Latitude. Step ONE – Place one point of the dividers on the object or target. Step TWO - Stretch the other point of the dividers to nearest Parallel of Latitude. Step THREE - Without disturbing the opening, move the dividers to the Latitude scale in the left or right margins. 2 Spread dividers and put one point on object The nearest line is 41° 20’N You want to insure it is just touching the line Read off the longitude at the bottom Answer 3 Step FOUR - Read the seconds or tenths of latitude. 4 1
The LATITUDE SCALE on a Small Scale Chart usually depicts decimal minutes. Seconds or Tenths 041 10.7’ N 041 10’ 42” N 10.5 min Degrees 10.0 min. Minutes
One Minute of Latitude equals One Nautical Mile DISTANCE One Minute of Latitude equals One Nautical Mile
6 seconds 1/10 of a Mile ONE NAUTICAL MILE The Second Scale on a Small Scale Chart 6 seconds 1/10 of a Mile SIXTY SECONDS OF LATITUDE ONE NAUTICAL MILE
Measuring the Seconds of Longitude Step ONE - Place one divider point on the object or target.. Step TWO - Stretch the other point of the dividers back to the nearest meridian of Longitude. 2 Step THREE - Without disturbing the opening, move the dividers to the Longitude Scale at the top or bottom margin. Spread dividers and put one point on object The nearest line is 071° 20’W You want to insure it is just touching the line Read off the longitude at the bottom Answer 1 3 Step FOUR - Read the seconds or tenths of Longitude. 4
The vertical line from the Bell. The Longitude Scale The vertical line from the Bell. Seconds or Tenths Degrees Minutes 071 01.4’ W or 071 01’ 24” W
END OF Session IV