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- 1. Land Navigation Term: Magnetic Declination Website: http://www.ngdc.noaa.gov/ Go to “Geomagnetic Data” Go to “Declination” Go to “Compute your declination” (N38 °, W77°) What is the declination for Warrenton? What was it on this day in 1994? 1974?
- 2. Magnetic Declination <ul><li>The number of degrees that a compass needle is pulled away from True North to point toward Magnetic North </li></ul>
- 3. Declination Diagram
- 4. Magnetic Flux <ul><li>The Earth’s Magnetic Field is NOT stationary </li></ul><ul><li>You need current map or use a declination chart or website </li></ul>
- 5. Warrenton 1994 Diagram <ul><li> - True North – the top of the earth </li></ul><ul><li>GN – Grid North – 1 ° 45’ </li></ul><ul><li>MN – Magnetic North – 10 ° </li></ul> GN MN
- 6. Declination for Warrenton <ul><li>2009= 10 °9’ </li></ul><ul><li>1994= 9°54’ </li></ul><ul><li>1974= 7°47’ </li></ul>
- 7. Why do we need to know all this? <ul><li>So that we can navigate using a map , the ground and compass . </li></ul><ul><li>You cannot follow a GN with a compass; nor can you plot a MN with a protractor. To assist you in making the conversion from MN to GN, and vice versa, a declination diagram is placed on the map margin. </li></ul><ul><li>When using a map - use a protractor to measure GRID Bearings. Do not use the compass magnetic needle. </li></ul><ul><li>When using the ground – use a Compass to Measure MAGNETIC Bearings. </li></ul>
- 8. <ul><li>From ground to map . </li></ul><ul><li>You measure the bearing of a landmark on the ground with a compass. It is 321° MN. </li></ul><ul><li>The G-M ANGLE on the Map is 10° </li></ul><ul><li>So MN to GN ADD 321° + 10° = 331° GN </li></ul><ul><ul><li>Draw this angle on your map </li></ul></ul><ul><li>From map to ground . </li></ul><ul><li>You measure the bearing of a point on the map with a protractor. It is 331° GN. </li></ul><ul><li>The G-M ANGLE on the Map is 10° </li></ul><ul><li>So GN to MN SUBTRACT 331 ° - 10° = 321° MN </li></ul><ul><ul><li>Put this on your compass </li></ul></ul>Map Information – Direction CONVERSION for Western Declination
- 9. Warrenton 1994 Diagram <ul><li> - True North – the top of the earth </li></ul><ul><li>GN – Grid North – 1 ° 45’ </li></ul><ul><li>MN – Magnetic North – 10 ° </li></ul><ul><li>IF you read 90° (east) on your map, what should your compass reading be to walk directly east? </li></ul> GN MN
- 10. Remember which North you are using! <ul><li>On your map decide if you will use: </li></ul><ul><ul><li>The True North (Outside border lines) </li></ul></ul><ul><ul><li>The Grid North (The inside grid lines) </li></ul></ul><ul><li>Use the Magnetic to Grid or Magnetic to True conversion </li></ul>
- 11. How to Orient a Map <ul><li>Find the declination diagram in the map's margin. Note the degree. </li></ul><ul><li>Line up one of the long sides of the compass with one of the map's north-south margins. Make sure the direction of travel arrow on the compass points to north on the map. </li></ul><ul><li>Rotate map and compass until the magnetic needle of the compass points to the number of degrees the magnetic north is to the right or left of map north. </li></ul>
- 12. Types of Compasses <ul><li>Military Lensatic </li></ul><ul><li>Baseplate Compass </li></ul><ul><li>Thumb Compass </li></ul>
- 13. Thumb Loop Lanyard Ring Sighting Slot Lens Luminous Bezel Line Luminous Magnetic Arrow Fixed Index Line Luminous Heading Luminous Sighting Dots Sighting Wire Graduated Straight Edge Floating Dial Bezel LENSATIC COMPASS PARTS and Features of a Lensatic compass PART 1 Basic Land Navigation 1. COVER 2. BASE 3. LENS REAR SITE
- 14. <ul><li>Degrees – common unit of measure is the degree (º). </li></ul><ul><li>360 Degrees to a Circle </li></ul><ul><li>Distance Between Red Marks = 5º </li></ul><ul><li>Distance Between Big Marks = 10º </li></ul><ul><li>Distance Between Red Numbers = 20º </li></ul><ul><li>N = 0º </li></ul><ul><li>E = 90º </li></ul><ul><li>S = 180º </li></ul><ul><li>W = 270º </li></ul>BLACK RING RED RING FLOATING DIAL SCALE <ul><li>Mils - is used mainly in artillery, tank, and mortar gunnery. AND is also used for very accurate azimuth land navigation. </li></ul><ul><li>6400 Mils to a Circle </li></ul><ul><li>Distance Between Small Marks = 20 Mils </li></ul><ul><li>Distance Between Big Marks = 100 Mils </li></ul><ul><li>Distance Between Numbers = 200 Mils </li></ul><ul><li>N = 64 (6400) </li></ul><ul><li>E = 16 (1600) </li></ul><ul><li>S = 32 (3200) </li></ul><ul><li>W = 48 (4800) </li></ul><ul><li>8.89 Mils = ½ Degree </li></ul><ul><li>17.78 Mils = 1 Degree </li></ul>PART 1 Basic Land Navigation
- 15. SIGHTING A LENSATIC COMPASS PART 1 Basic Land Navigation
- 16. SIGHTING A LENSATIC COMPASS PART 1 Basic Land Navigation
- 17. SIGHTING A LENSATIC COMPASS PART 1 Basic Land Navigation
- 18. SIGHTING A LENSATIC COMPASS PART 1 Basic Land Navigation
- 19. 65° AZIMUTH (11.5m = 1,150mils) SIGHTING A LENSATIC COMPASS PART 1 Basic Land Navigation
- 20. What if <ul><li>You wanted to hike from the hill 700 west of the hort building to the tower on View Tree Road. What map azimuth do you measure? </li></ul><ul><li>What would your compass reading be? </li></ul>
- 21. Handout Map Answer in your notebook <ul><li>How far is it on Rt 678 from where Lower Waterloo Rd splits off & remeets 678. </li></ul><ul><li>What is the 6 digit coord. for the Hort Bdg? </li></ul><ul><li>What terrain feature is found at 526 905? </li></ul><ul><li>What terrain feature is found at 553 919? </li></ul><ul><li>What is the elevation at Fauquier High School? </li></ul><ul><li>What is the elevation of Fauquier Hospital? </li></ul>

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