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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.
TrueNorth
MagneticNorth
GridNorth
Map Reading III
Types of Azimuth
An 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 III
Measuring an AzimuthCompasses
302010
W
E
E. decl.
W.decl.
mm
BASE PLATE
DIRECTION OFTRAVEL ARROW
BASE LINE
INDEX LINE
ORIENTEERINGARROW
ROTATINGDIAL
FLOATINGMAGNETIC
NEEDLE
ORIENTEERINGLINE
N
S
11
/ 21
/ 2
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 1 2 3 4 5 6 7 8 9 10
8-DIGIT GRID:EG 1 2 3 4 5 6 7 8
1000M 100M 10M 1M 1000M 100M 10M 1M
1000M 100M 10M 1000M 100M 10M
Map Reading III
Reading a GRID
COLUMBUS: 16S FL (or GL) 08 45 74 25
TENINO: 10T EH (or EG) 15 85 82 20
Square Identification
8-DigitGrid
(w/in 10 M)
08 74 (4 digit)084 742 (6 digit)
Map Reading III
Reading a GRID
75
75
27 27
1. Read RIGHT2.
T
hen
UP
76
76
28 281000
METERS
1000 METERS
Map Reading III
Using a Protractor
MAKE SURETHAT YOUUSE THE
CORRECTSCALE 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 or250 M
Map Reading III
Reading a Protractor08
08
08 45 74 25
74 74
09
09
7575
Line-UpVertical Scale of
protractor with 08 Grid
RIGHTU
P
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- EG1350 8009 and • POS 2- EG1610 8055 on the map.
EG 1350 8009
POS 1.50
TENINO Map SheetPoint #1
80.0
9
13
1. Read RIGHT
POS 1
STEP 1. Locate two points:• POS 1- EG13508009 and • POS 2- EG1610 8055 on the map.
POS 2
EG 1610 8055
TENINO Map Sheet; Point #2
80.10
.55
1. Read RIGHT
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 0-180 degree line on the vertical grid line.
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 AZIMUTH 360 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 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 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 ExerciseQuestion #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 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 III
Answer: 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 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.