Understanding Latitude and Longitude: Measuring Techniques and Rules

1. Session IV Measuring Latitude and Longitude

2. General Rules • 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

3. LAT/LON Expressions On a Nautical Chart: • 042 deg 56 min45 sec North • 072 deg 45 min25 sec West Typical GPS or LORAN read out: • 042 56.750 N • 072 45.417 W

4. Rules for reading LAT/LON On a Nautical Chart: • Read theDegreesfrom the LAT/LON scales. • Read theMinutesfrom the LAT/LON scales. • Measure theSeconds or Tenth’s of a Minute.

5. Measuring the Seconds of Latitude. 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. Step FOUR- Read the seconds or tenths of latitude.

6. 041 10.7’ N 11.0 min. 10.5 min

7. DISTANCE One Minute of Latitude equals One Nautical Mile

8. DISTANCE Sixty Seconds of Latitude equals One Nautical Mile

9. 6 seconds 1/10 of a Mile SIXTY SECONDS OF LATITUDE ONE NAUTICAL MILE

10. Measuring the Seconds of Longitude Step TWO- Stretch the other point of the dividers back to the nearest meridian of Longitude. Step ONE- Place one divider point on the object or target.. Step THREE- Without disturbing the opening, move the dividers to the Longitude Scale at the top or bottom margin.

12. END OF Session IV