# map reading ii map reading iii reading a grid & determining direction grc jrotc col. alexander

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• Map Reading IIIOutlinePurposeNorth (3 types)Types of AzimuthsMeasuring AzimuthsPlotting Azimuths Practical ExerciseSummaryConclusion

• Map Reading IIIPurposeTo 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 IIINorth (x3 types)True North- line through North Pole.

Magnetic North- direction to northern magnetic pole (compass).

Grid North-North as established by map maker.TrueNorthMagneticNorthGridNorth

• Map Reading IIITypes of AzimuthAn azimuth is an angle measuredclockwise 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 IIIMeasuring an Azimuth Protractors

CompassesEWSN360 degrees in a CIRCLE

• Map Reading IIIMeasuring an Azimuth Protractors

• Map Reading IIIMeasuring an AzimuthCompassesMagnetic Lensatic Compass(Military Type)

Silva Polaris Compass(Civilian Orienteering)

• Map Reading III3 Ways to Plot AzimuthsPlotting Azimuths between 2 points on a map.Converting Magnetic Azimuths to Grid Azimuths.Converting Grid Azimuths to Magnetic Azimuths.

• Map Reading IIIReading a GRID10-DIGIT GRID:EG 1 2 3 4 5 6 7 8 9 108-DIGIT GRID:EG 1 2 3 4 5 6 7 81000M 100M 10M 1M 1000M 100M 10M 1M1000M 100M 10M 1000M 100M 10M

• Map Reading IIIReading a GRIDCOLUMBUS: 16SFL (or GL)08 45 74 25

TENINO: 10TEH (or EG)15 85 82 20Square Identification8-DigitGrid(w/in 10 M)08 74 (4 digit)084 742 (6 digit)

METERS1000 METERS

• Map Reading IIIUsing a ProtractorMAKE SURETHAT YOUUSE THECORRECTSCALE for the MAP you have

1:50,000

• Map Reading IIIUsing & Reading a Protractor1 GRID SQUARE = 1000 M x 1000 MEach # (1, 2, 3, etc) = 100 METERS

Each | in between =50 METERS25 or250 M

• Map Reading IIIReading a Protractor080808 45 74 25747409097575Line-UpVertical Scale of protractor with 08 GridRIGHTUPSlide protractor over to the RIGHT - 45Move UP 25 & place a dot or markUse Protractor

• Map Reading IIICAUTION: You cant put your pen/marker thru the plastic edge/overhang !MUST slide protractor to the RIGHT to place markMUST BE PRECISE

• STEP 1. Locate 2 points: POS 1- EG1350 8009 and POS 2- EG1610 8055 on the map..50TENINO Map SheetPoint #180.09131. Read RIGHT

• STEP 1. Locate two points: POS 1- EG13508009 and POS 2- EG1610 8055 on the map.TENINO Map Sheet; Point #280.10.551. Read RIGHT

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

• POS 2STEP 3. Place index of protractor on line at a vertical (North/South) or horizontal (East/West) grid line. Keep the 0-180 degree line on the vertical grid line.

• STEP 4. Read the angle value on the grid scale.POS 280 degrees1420 mils

• Map Reading IIIRULE #1: IF THE AZIMUTH IS MORE THAN 180 DEGREES, THEN SUBTRACT 180 DEGREES.EXAMPLE: AZIMUTH 215 DEGREES-180 DEGREESBACK AZIMUTH 35 DEGREESRULE #2: IF THE AZIMUTH IS 180 DEGREES OR LESS, THEN ADD 180 DEGREES.EXAMPLE: AZIMUTH 180 DEGREES+180 DEGREESBACK AZIMUTH360 DEGREESBACK AZIMUTH

• Map Reading III3 Ways to Plot AzimuthsPlotting Azimuths between 2 points on a map.Converting Magnetic Azimuths to Grid Azimuths.Converting Grid Azimuths to Magnetic Azimuths.

• Map Reading IIIPlotting AzimuthsAzimuths 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 IIIPlotting Azimuths; Declination DiagramsWhat is the GM Angle for Tenino?What is the GM Angle for Columbus?

• Map Reading IIIPractical ExerciseQuestion #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 IIIMAGNETIC AZIMUTH: 275 DEGREESWESTERLY G-M ANGLE: + 21 DEGREESGRID AZIMUTH: 296 DEGREESAnswer: # 1BONUS:GRID AZIMUTH: 296 DEGREESOPPOSITE DIRECTION:- 180 DEGREESBACK AZIMUTH: 116 DEGREES

• Map Reading IIIPractical ExerciseQuestion #2Given 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.

• Map Reading IIIGRID AZIMUTH: 179 DEGREESEASTERLY G-M ANGLE: -21 DEGREESMAGNETIC AZIMUTH:158 DEGREESAnswer: # 2BONUS:MAGNETIC AZIMUTH:158 DEGREESOPPOSITE DIRECTION: +180 DEGREESBACK AZIMUTH: 338 DEGREES

• Map Reading IIIPractical ExerciseQuestion #3 (TENINO Map)What TERRAIN FEATURE is located at EG 06159015?

What TERRAIN FEATURE is located at EG 12859835?

What TERRAIN FEATURE is located at EG 10309650?

What TERRAIN FEATURE is located at EG14508545?

What TERRAIN FEATURE is located at EG 02407981?

What TERRAIN FEATURE is located at EG 15329335?

What TERRAIN FEATURE is located at EH 18700030?

• Map Reading IIIAnswer: PE # 3 What TERRAIN FEATURE is located at EG 06159015? - DEPRESSION

What TERRAIN FEATURE is located at EG 12859835? - SADDLE What TERRAIN FEATURE is located at EG 10309650? RIDGE

What TERRAIN FEATURE is located at EG14508545? CLIFF

What TERRAIN FEATURE is located at EG 02407981? - DRAW

What TERRAIN FEATURE is located at EG 15329335? - SPUR

What TERRAIN FEATURE is located at EH 18700030? - HILL

• Map Reading IIISummaryPurposeNorthTypes of AzimuthsMeasuring AzimuthsPlotting Azimuths Practical Exercise