NOVA SCOTIAGROUND SEARCH
AND RESCUE ASSOCIATION
SEARCHER – Module one
SEARCHER
MODULE 1
MAP READING AND COMPASS
NOTICE
Map skills are not optional for searchers.
ALL SEARCHERS MUST be able to use maps
easily and effectively
TOPOGRAPHIC MAPS
A MAP is a pictorial representation of a portion
of the earth’s surface
Many types of maps exist but for our purpose,
they can be divided into two main categories:
TOPOGRAPHIC MAPS
Those that, record to scale, natural and manmade features
Those that record and display other types of
information and features
TOPOGRAPHIC MAPS
Maps that record to scale and features are:
Atlas Maps- very small scale maps showing whole
countries,continents,or regions
Topographic Maps-used primarily for map reading. They show as
much detail as their scale allows. Their purpose is to present a
complete and accurate picture of the ground as it exist,
Plans- very large scale maps drawn in great detail. A plan covers
so small an area, they are used basically for special operations
TOPOGRAPHIC MAPS
Maps that display other types of information are:
Relief Maps- solid maps built as a model,using any
scale
Road Maps-intended only for use in road connections
Photo Maps- produced by making a mosaic of vertical
airphotos so as to completely cover an area to be
mapped
TOPOGRAPHIC MAPS
The most useful and commonly used map by the
searcher is the TOPOGRAPHIC MAP, which can
be defined as:
A two dimensional representation of a three
dimensional configuration of a land surface
TOPOGRAHIC MAPS
Advantages of a Topographic Map
Represent physical features of the earth’s
surface without distortion
Made to scale,which means there is a ratio of
the distance on the map to the actual distance
on the ground
TOPOGRAPHIC MAPS
Topographic maps…cont’d;
Provide a base of all SAR activities
Have grids which allow the searcher to describe a point
on the map with accuracy
Provide a wealth of information about a particular
location
TOPOGRAPHIC MAPS
Disadvantages of a Topographic Map
Most common scale 1:50,000, meaning 2cmon
the map equal 1km on the ground
Difficult to chart maneuvers
Updated only every 10 years or so, and may be
incomplete
MAP CONVENTIONS
Topographic maps have a wide variety of
applications
Maps are made with north at the top
A black margin frames the ground area
represented
MAP CONVENTION
The title, Scale, Contour Lines,Reference
System,Legends and other information are
shown outside, and displayed in the margins
Topographic map symbols are usually displayed
on the back of the map
MAP CONVENTION
Instructors note
Insert a copy of your local map, to help familiarize your student to
the area
MAP CONVENTIONS
TITLE
In Canada, there is a National Topographic
System (NTS) of indexing maps
Each topographic map is named after some
prominent community or place within the area.
The title of our map is__________
MAP CONVENTIONS
TITLE…cont’d
The map number is usually displayed in the
upper right corner of the map. The number of our
map is ____________
The map number and index number to adjoining
maps are usually displayed in the lower right
corner
MAP CONVENTION
SCALE
The scale of a map is a ration between a unit of
length on the map and the actual distance
represented on the ground and can be stated in
three ways
MAP CONVENTION
VERBAL-scale in the form of an equation
example, one cm to one km, meaning one cm
on the map represents one km on the ground
MAP CONVENTION
SCALE …cont’d
Ratio or Fractional –for example
1:50,000 or 1/50,000, meaning that one unit
(centimeter,inches,etc) on the map is equivalent to
50,000 like units on the ground
Map Distance/Ground Distance1cm/50,000cm = 1cm/500m = 1cm/0.5km
MAP CONVENTION
SCALE…cont’d
Graphic Scale- a bar scale marked off to show
distance in Kilometers, miles, or any unit.
Check your local map to view the scale bar
MAP CONVENTION
SCALE …cont’d
The scale 1/50,000 map is the most commonly used by SAR
personnel. The scale simply states :
1 cm on the map equals 0.5 km on the ground
MAP CONVENTION
SCALE EXERCISE
Convert Fractional Scales to Verbal
Fractional Scales
Verbal Scales
1/20,000
1cm represents____km
1/50,000
1cm represents____km
1/250,000
1cm represents____km
1/1,000,000
1cm represents____km
MAP CONVENTION
SCALE EXERCISE…cont’d
Convert Verbal Scales to Fractional Scales
Verbal
Fractional
1 cm equals ten feet
__________________
1 cm equals ten km
__________________
1 inch equals one mile
__________________
1 cm equals 200 km
__________________
MAP CONVENTION
MEASURING DISTANCE
There are several methods for measuring
distance between two points on a map.
The simplest uses the graphic scale at the
bottom of the map. Simply measure between the
two points with a ruler then measure the same
distance from the scale
MAP CONVENTION
MEASURING …cont’d
If you don’t have a ruler, the two points may simply be marked on the edge of
a piece of paper then laid along the scale. You will need to measure the
distance in sections if it is longer than the graphic scale
Another method is to measure the two points with a piece of string and lay that
along the scale
Use a Romer that is designed for the scale of the map being measured
MAP CONVENTION
MEASURING…cont’d
Distance may also be measured with a map wheel,
were it is rolled along the map and the display will be
either be on a dial or LED screen
Finally, distance can be measured on a map, by using
the scale and simple mathematics, this distance can be
converted to actual ground distance
MAP CONVENTION
Instructor note
Using your local map have students find and measure
between two points. And then convert the distance to
miles and km
MAP CONVENTION
GRID REFERENCE SYSTEM
Topographic maps have two types of grid
reference systems:
Geographic (latitude and longitude)
Universal Transverse Mercator (UTM)
MAP CONVENTION
Geographic Grid Reference System
Locations on a map are given by Latitude and
Longitude Coordinates
Latitude is measured by degrees, from 0-90 north and
south of the equator
Latitude is parallel to the equator and are called
Parallels
MAP CONVENTION
Grid system…cont’d
Longitude is an angular distance measured east and
west from the prime meridian which runs through
Greenwich,England. It ranges from 0-180 degrees east
or west. Lines of longitude are termed meridians and
encircle the earth in a direction perpendicular to the
equator
MAP CONVENTION
Grid System…cont’d
Latitude and Longitude coordinates are expressed in
units of Degrees, minutes, and seconds.
Each degree is subdivided into 60 minutes(‘) and each
minute is subdivide into 60 seconds(“)
MAP CONVENTION
MAP CONVENTION
Grid System …cont’d
By convention, Latitude is stated first, followed
by Longitude.
Also include the direction you are referring, such
as North,or south latitude
East or west Longitude
MAP CONVENTION
Grid System …cont’d
To read Latitude and Longitude of a map, start at
the lower right corner and remember the
following:
FIRST GO UP AND THEN GO LEFT
MAP CONVENTION
Grid system…cont’d
It is critical that all ground searchers understand the use
of the geographic grid since they may have to
communicate their position to an aircraft/helicopter or
vessel, and virtually all their navigational equipment is
designed to use the geographic grid system only.
MAP CONVENTION
Instructor note
Using your local map, have students practice 4 or 5
points and identify by using lat/long.
MAP CONVENTION
Universal Transverse Mercator (UTM) Grid
Reference System
The UTM grid is more “user friendly”
The grid consists of a system of blue lines
forming 2cm squares over the entire map
Each square represents 1 square kilometre
MAP CONVENTION
UTM …cont’d
The entire UTM grid is comprised of
100x100kilometre blocks. The grid lines are
numbered every kilometre, 0-99 eastward and
northward within each block. These numbers are
printed along the borders of the map and at
intervals on the map area
MAP CONVEBTION
UTM..cont’d
Using this system, any point can be designated
to an increment of 1 meter
The UTM system is commonly called the Military
Grid Reference System
MAP CONVENTION
UTM…cont’d
A grid map reference is given in six figures and
is unique to a particular map
A six figure grid reference will locate any point
within 100 meters, and is usually accurate
enough for SAR purposes
MAP CONVENTION
UTM…cont’d
Since grid numbers are repeated every 100
kilometres, the map name and number must be
stated along with the grid map reference
The method used to determine a six figure grid
reference is illustrated in the diagram
UTM EXERCISE
MAP CONVENTION
Instructor note
using the same points as in lat/long. Exercise, have students now
find the points using UTM reference system
MAP CONVENTION
DATUMS
Map grids are based on a series of accurately
surveyed points called Datums
Two Datums currently in use are the North
American Datum 1927,(NAD 27) and North
American Datum 1983(NAD 83)
MAP CONVENTION
Datums…cont’d
These two Datums are several hundred metres
apart in grid spacing thus,
It is very important if you are using GPS, to
check to ensure you are using the correct datum
Map datums are located on the bottom margin of
the map
MAP CONVENTION
MAP SYMBOLS
Symbols are used to represent features on the ground.
The key for these symbols is either on the reverse side
of the map or in the margin
All map symbols on Canadian topographic maps
conform to the following colour code:
MAP CONVENTION
Canadian colour code
black
human-made features
blue
water
green
forest or vegetation
brown
elevation (contours)
white
open areas,field,or snowfields
red
highways
orange
secondary or dirt roads
pink
high population density areas
purple
updated data
MAP CONVENTION
Instructors note
show students the location of the symbols on the local chart you are using.
MAP CONVENTION
TOPOGRAPHIC CONTOURS
A map is prepared on a flat (2-D) paper but the surface
it represents has three dimensions. On topographic
maps the third dimension or elevation can be indicated
with Contour Lines
Map convention
Contours…cont’d
A CONTOUR LINE on a map is a line that connects
points of equal elevation above sea level.
The vertical distance between two contour lines is the
Contour Interval
MAP CONVENTION
Contour..cont’d
The contour interval is located on the bottom margin of
the map
The contour interval for our working map is ___
Contour lines are drawn with reference to a datum
plane or zero contour,usually mean sea level
MAP CONVENTION
Contour…cont’d
There are three kinds of contour lines
elevation contours
brown lines
depression contours
hachured brown lines
water depth contours
blue lines
On most topographic maps, every fifth contour line is printed
darker, and is usually labeled with its elevation.This is called the
Index Contour
MAP CONVENTION
1.
2.
The following 10 rules apply to all contour lines
All points on the same line are at the same
elevation
All contour lines close somewhere, although it
may be outside the map at hand
MAP CONVENTION
Rules …cont’d
3. Contour lines never cross, except when they are representing an
overhanging cliff in which case those lines beneath the overhang
are dotted. On a vertical cliff several contour lines may become
superimposed
4. Contour lines never divide
5. Contour are far apart on a gentle slope
MAP CONVENTION
Rules…cont’d
6. Contours are close together on a steep slope
7. Contours bend upstream in valleys and cross streams
at right angles
8. On level ground there are no contours
9. An isolated closed contour has the same elevation as
the next adjacent contour
10. All points inside a depression contour are lower than
the line
MAP CARE
In the field, maps can be subject to a considerable
amount of abuse. Maps are fragile,expensive and often
in short supply. HANDLE WITH CARE
Avoid opening a map full out in the open air especially if
there is a slight breeze. The wind will cause small tears
to start and quickly spread
Avoid refolding the map any more than you must.
Refolding causes the paper to weaken and results in
tears or loss of detail
MAP CARE
A map should be folded using the following procedure:
Fold the map in half down its longest length with the
map showing outwards
Next fold the map three times the other way in an
accordion fashion
The idea is to fold the map to a suitable carrying size
while ensuring that there is a reasonable size area to
study when the two folds are open
MAP CARE
Try to keep maps dry at all times. This can be
accomplished by placing it in clear,sealable plastic bag
or map case
If a map becomes wet, open them as soon as possible
and allow them to dry. Wet maps will tear and stain
easily
Laminating maps or covering them with clear adhesive
plastic film will increase their durability, but will make
them cumbersome to carry in the field
MAP ORIENTATION
A map is “ORIENTATED” when it is turned by the map
reader to correspond with the ground it represents
The next four slides will describe ways to “orientate” a
map
MAP ORIENTATION
Orientation 1
Compass
Set compass to north
Place orientating lines on the compass parallel to north
on the map
Rotate map until “ red goes to bed”
MAP ORIENTATION
Orientation 2
Distant Objects
Find two objects/natural landmarks that are also distinct
on the map
Stand between the two objects
Orientate the map to line up with the objects
MAP ORIENTATION
Orientation 3
Watch and Sun
Orientate your watch by pointing the hour hand directly
at the sun
Bisect the angle between the hour hand and 12 o’clock
You will have an imaginary line running north and
south
The direction reverses from morning to evening
MAP ORIENTATION
Orientation 4
Stars
Locate the pole star
Face it and you are facing north
You can locate the pole star by using the big dipper
DIRECTIONS and TRENDS
Directions are angular measurements with respect to
the position of the observer,north, and the position of
the distant object or intended destination course
Directions may be expressed in terms of-points of the
compass-Bearings-Azimuths
Features that lack a particular direction are said to
“trend”(a lake may have a sw-ne trend)
DIRECTIONS and TRENDS
CARDINAL and INTERCARDINAL Points of a
COMPASS
A compass rose may be broken down into a series of
16 Cardinal and Intercardnial points
All 16 Cardinal and Intercardinal points are separated
by 22.5 degrees
DIRECTIONS and TRENDS
Instructors note
Using your local map determine the trends of
lakes,runways,ridgelines etc.
DIRECTIONS and TRENDS
BEARINGS
Bearings are always measured within the four
quadrants of the directional circle
Bearings are always measured as the angle from the
North or South Pole towards either the East or West
Bearings cannot exceed 90 degrees
DIRECTIONS and TRENDS
Instructors note
Using BLM No. 9 determine the bearings for the
following 8 courses
A,B,C,D,E,F,G,H
DIRECTIONS and TRENDS
AZIMUTHS
Azimuths are directions expressed as angles,measured
clockwise from North through the full range of the
directional circle.
Azimuths range from 0-360 degrees
The following diagram illustrates how Southwest would
be expressed as 225 degrees
DIRECTIONS AND TRENDS
AZIMUTH EXERCISE
Using BLM 10, plot the following bearings as azimuths
a. S20E
B. N75W
C. S35W
D N45E
E. N10W
MAGNETIC DECLINATION
Direction can be defined as the position of one point in
relation to another
On a map there are three primary references that are
used to measure direction:
True North
Magnetic North
Grid North
MAGNETIC DECLINATION
Declination…cont’d
True North (TN)- The direction of the earth’s North geographic
pole. All lines of Longitude meet there
Magnetic North(MN)- The direction to the earth’s North magnetic
pole. This is were all compass needles point.
Grid North(GN)- The direction indicated by the N-S lines on the
grid which overlay the map.Grid north is slightly different than
true north, for GSAR purposes, grid north and true north are the
same
MAGNETIC DECLINATION
The angular difference between True North and
Magnetic North is called Magnetic Declination
All topographic maps display a declination diagram
either on the right hand margin or to the left on the
bottom margin (only on newer topo maps)
MAGNETIC DECLINATION
DECLINATION…cont’d
Depending on your location,declination will be either
east or west. In Nova Scotia all declinations are
westerly
A line passing through both magnetic and true north
poles has no declination. It is referred to as the
AGONIC LINE
The agonic line in Canada passes through Saskatchewan
MAGNETIC DECLINATION
Calculating current declination
ALL searchers responsible for navigation should check
the map each time they use it, and calculate the current
declination if required
The sample calculation is based on BLM No. 12
The diagram indicates the declination was 23
degrees17’ in 1976 and was decreasing 5.4’annually
MAGNETIC DECLINATION
Calculating current declination…cont’d
Calculate the number of years since the declination was
established,
present year(A)-1976= ( B)years
Multiply the annual change by the number of years, to
obtain the total declination change,
B X 5.4= TOTAL CHANGE in minutes
remember,1 degree equals 60 minutes
MAGNETIC DECLINATION
…CONT’D
Since declination is decreasing the angle between grid
north and magnetic north is decreasing. Therefore the
total amount of change is subtracted from the original
figure.
It is virtually impossible to measure fractions of degrees
with a hand-held compass, so round off to the nearest
degree
MAGNETIC DECLINATION
Declination…cont’d
Note on which side of the grid north arrow the magnetic
north arrow is located. If it is right the declination is east.
Conversely if it is left, the declination is west.
Each year make a pencil note of the new declination
beside the declination diagram on the map
MAGNETIC DECLINATION
Instructors note
Using your local map have the students determine the current magnetic
declination
CONVERTING BEARINGS and AZIMUTHS
Whether the declination is east or west is critical, when
it comes to map and compass work
Whenever you take a grid direction from a map and
want to follow it with a compass, you must take into
account the magnetic declination.
Conversely, the same holds true when you want to plot
field data taken from your compass,onto a map
MAGNETIC DECLINATION
All searchers responsible for navigation should
remember the following rhyme:
Declination West-Magnetic Best
Declination East-Magnetic Least
MAGNETIC DECLINATION
Cont’d
The rhyme can be broken down into the following rules
to go from grid bearing to magnetic bearing
ADD DECLINATION
to go from magnetic bearing to a grid bearing
SUBTRACT DECLINATION
MAGNETIC DECLINATION
Cont’d
With a Easterly Declination
To go from a grid bearing to a magnetic bearing
Subtract declination
To go from a magnetic bearing to a grid bearing
Add declination
MAGNETIC DECLINATION
Converting Bearing Exercise
Complete the following
mag.dec.17E
Mag. Dec. 24 W
Azimuth (mag) 264
Azimuth (true) 167
Azimuth (true)_____
Azimuth (mag)________
mag.dec. 16W
Azimuth (mag) 094
Azimuth (true)______
MAG.DEC.17E
Bearing (true) 17 E
Bearing (mag) ________
REFERENCES
Merry,Wayne,1999, Basic Ground Search and Rescue in
Canada: A Home Study Guide, Context North.
Smith,Richard:LaValla,Richard: Hood,Rick,Lawson, Norman and
Kerr,Guy 2003,Field Operating Guide to Search and Rescue
(FOG SAR)-SAR Skills Handbook, ERI Canada, Alberta, Canada
Newfoundland and Labrador Search and Rescue
Association,2002, Provincial Training Standards Manual