Map Reading II Map Reading III Reading a Grid & Determining Direction GRC JROTC COL. ALEXANDER

Map Reading III Outline Purpose North (3 types) Types of Azimuths Measuring Azimuths Plotting Azimuths Practical Exercise Summary Conclusion

Map Reading III Purpose To lay the groundwork for successful map reading and land navigation by exposing the cadet to determining grid and magnetic azimuths using a protractor and compass.

Map Reading III North (x3 types) True North- line through North Pole. Magnetic North- direction to northern magnetic pole (compass). Grid North-North as established by map maker. True North Magnetic North Grid North

Map Reading III Types of Azimuth An azimuth is an angle measured clockwise from a base line direction (north). Grid- angle between grid north and a straight line plotted between two points on a map. Magnetic- angle determined by using a compass. Back- opposite direction of an azimuth.

Map Reading III Measuring an Azimuth Protractors Compasses E W S N 360 degrees in a CIRCLE

Map Reading III Measuring an Azimuth Protractors

Map Reading III Measuring an Azimuth Compasses Magnetic Lensatic Compass (Military Type) Silva Polaris Compass (Civilian Orienteering)

Map Reading III 3 Ways to Plot Azimuths 1. Plotting Azimuths between 2 points on a map. 2. Converting Magnetic Azimuths to Grid Azimuths. 3. Converting Grid Azimuths to Magnetic Azimuths.

Map Reading III Reading a GRID 10-DIGIT GRID: EG DIGIT GRID: EG M 100M 10M 1M 1000M 100M 10M

Grid Zone Map Reading III Reading a GRID COLUMBUS: 16SFL (or GL) TENINO: 10TEH (or EG) Square Identification 8-Digit Grid (w/in 10 M) (4 digit) (6 digit)

Map Reading III Reading a GRID Read RIGHT 2. Then UP METERS1000METERS 1000 METERS

Map Reading III Using a Protractor MAKE SURE THAT YOU USE THE CORRECT SCALE for the MAP you have 1:50,000

Map Reading III Using & Reading a Protractor 1 “GRID SQUARE” = 1000 M x 1000 M Each # (1, 2, 3, etc) = 100 METERS Each | in between = 50 METERS 25 or 250 M

Map Reading III Reading a Protractor Line-Up Vertical Scale of protractor with 08 Grid RIGHT UP Slide protractor over to the RIGHT - 45 Move UP 25 & place a dot or mark Use Protractor

Map Reading III CAUTION: You can’t put your pen/marker thru the plastic edge/overhang ! MUST slide protractor to the RIGHT to place mark MUST BE PRECISE

STEP 1. Locate 2 points: POS 1- EG and POS 2- EG on the map. EG POS 1.50 TENINO Map Sheet Point # Read RIGHT 2. Then UP

POS 1 STEP 1. Locate two points: POS 1- EG and POS 2- EG on the map. POS 2 EG TENINO Map Sheet; Point # Read RIGHT 2. Then UP

STEP 2. Connect the points with a straight edge. Draw a line extending beyond the points. POS 2 POS 1 Use a STRAIGHT EDGE

POS 2 POS 1 STEP 3. Place index of protractor on line at a vertical (North/South) or horizontal (East/West) grid line. Keep the degree line on the vertical grid line.

STEP 4. Read the angle value on the grid scale. POS 2 POS 1 80 degrees 1420 mils

Map Reading III RULE #1: IF THE AZIMUTH IS MORE THAN 180 DEGREES, THEN SUBTRACT 180 DEGREES. EXAMPLE: AZIMUTH 215 DEGREES -180 DEGREES BACK AZIMUTH 35 DEGREES RULE #2: IF THE AZIMUTH IS 180 DEGREES OR LESS, THEN ADD 180 DEGREES. EXAMPLE: AZIMUTH 180 DEGREES +180 DEGREES BACK AZIMUTH360 DEGREES BACK AZIMUTH

Map Reading III 3 Ways to Plot Azimuths 1. Plotting Azimuths between 2 points on a map. 2. Converting Magnetic Azimuths to Grid Azimuths. 3. Converting Grid Azimuths to Magnetic Azimuths.

Map Reading III Plotting Azimuths Azimuths must be converted to the environment they will be used in. Grid to Magnetic (map-to-compass) Magnetic to Grid (compass-to-map). Use the Declination Diagram to find the conversion angle (GM Angle). For Grid to Magnetic Conversion Remember: Right-Add-Left-Subtract (RALS): GM to the Right Add GM. GM to the Left Subtract the GM.

Map Reading III Plotting Azimuths; Declination Diagrams What is the GM Angle for Tenino?What is the GM Angle for Columbus?

Map Reading III Practical Exercise Question #1: Given a Tenino Map (hint: find Declination Diagram). From your location you see a radio tower on magnetic azimuth of 275 degrees. What azimuth will you use to locate the radio tower on your map? Bonus: What would be the GRID azimuth from the tower to your position?

Map Reading III MAGNETIC AZIMUTH: 275 DEGREES WESTERLY G-M ANGLE: + 21 DEGREES GRID AZIMUTH: 296 DEGREES Answer: # 1 BONUS: GRID AZIMUTH: 296 DEGREES OPPOSITE DIRECTION:- 180 DEGREES BACK AZIMUTH: 116 DEGREES

Map Reading III Practical Exercise Question #2 Given a Tenino Map (hint: find Declination Diagram). After determining the map location for your rendezvous with the B Company platoon leader, you plotted the grid azimuth at 179 degrees. There are mine fields on both sides of your route so you want to make sure you travel in the right direction. What azimuth will you tell your compass man to follow? Bonus: You got half way to the rendezvous and were directed to dispatch a squad back to your original location. What azimuth should your squad leader follow?

Map Reading III GRID AZIMUTH: 179 DEGREES EASTERLY G-M ANGLE: -21 DEGREES MAGNETIC AZIMUTH:158 DEGREES Answer: # 2 BONUS: MAGNETIC AZIMUTH:158 DEGREES OPPOSITE DIRECTION: +180 DEGREES BACK AZIMUTH: 338 DEGREES

Map Reading III Practical Exercise Question #3 (TENINO Map) What TERRAIN FEATURE is located at EG ? What TERRAIN FEATURE is located at EG ? What TERRAIN FEATURE is located at EG ? What TERRAIN FEATURE is located at EG ? What TERRAIN FEATURE is located at EG ? What TERRAIN FEATURE is located at EG ? What TERRAIN FEATURE is located at EH ?

Map Reading III Answer: PE # 3 What TERRAIN FEATURE is located at EG ? - DEPRESSION What TERRAIN FEATURE is located at EG ? - SADDLE What TERRAIN FEATURE is located at EG ? – RIDGE What TERRAIN FEATURE is located at EG ? – CLIFF What TERRAIN FEATURE is located at EG ? - DRAW What TERRAIN FEATURE is located at EG ? - SPUR What TERRAIN FEATURE is located at EH ? - HILL

Map Reading III Summary Purpose North Types of Azimuths Measuring Azimuths Plotting Azimuths Practical Exercise

Map Reading III Conclusion Successful land navigations starts with map reading skills. Your ability to swap information between grid a magnetic environments is essential to helping you fight, survive, and win on the battlefield.

Map Reading II Map Reading III Reading a Grid & Determining Direction GRC JROTC COL. ALEXANDER