nova scotia ground search and rescue association

NOVA SCOTIAGROUND SEARCH AND RESCUE ASSOCIATION

SEARCHER – Module one

SEARCHER

MODULE 1MAP 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 man-made 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 regionsTopographic 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 scaleRoad Maps-intended only for use in road connectionsPhoto 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 distortionMade 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 activitiesHave grids which allow the searcher to describe a point on the map with accuracyProvide 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 groundDifficult to chart maneuversUpdated only every 10 years or so, and may be incomplete

MAP CONVENTIONS

Topographic maps have a wide variety of applicationsMaps are made with north at the topA 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 marginsTopographic 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

TITLEIn Canada, there is a National Topographic System (NTS) of indexing mapsEach 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

SCALEThe 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 groundMap Distance/Ground Distance-

1cm/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 SYSTEMTopographic maps have two types of grid reference systems:

Geographic (latitude and longitude)

Universal Transverse Mercator (UTM)

MAP CONVENTION

Geographic Grid Reference SystemLocations on a map are given by Latitude and Longitude CoordinatesLatitude is measured by degrees, from 0-90 north and south of the equatorLatitude 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 latitudeEast 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 mapEach square represents 1 square kilometre

MAP CONVENTION

UTM …cont’dThe 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 meterThe UTM system is commonly called the Military Grid Reference System

MAP CONVENTION

UTM…cont’dA grid map reference is given in six figures and is unique to a particular mapA 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 referenceThe 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

DATUMSMap grids are based on a series of accurately surveyed points called DatumsTwo Datums currently in use are the North American Datum 1927,(NAD 27) and North American Datum 1983(NAD 83)

MAP CONVENTION

Datums…cont’dThese 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 datumMap datums are located on the bottom margin of the map

MAP CONVENTION

MAP SYMBOLSSymbols 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 marginAll 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’dA 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 mapThe 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’dThere 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

The following 10 rules apply to all contour lines1. All points on the same line are at the same

elevation2. 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 divide5. Contour are far apart on a gentle slope

MAP CONVENTION

Rules…cont’d

6. Contours are close together on a steep slope7. Contours bend upstream in valleys and cross streams at

right angles8. On level ground there are no contours9. An isolated closed contour has the same elevation as

the next adjacent contour10. 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 CAREAvoid 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 spreadAvoid 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 outwardsNext fold the map three times the other way in an accordion fashionThe 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 caseIf a map becomes wet, open them as soon as possible and allow them to dry. Wet maps will tear and stain easilyLaminating 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 1Compass

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 2Distant 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 3Watch 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 4Stars

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 courseDirections may be expressed in terms of-points of the compass-Bearings-AzimuthsFeatures 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 COMPASSA 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

BEARINGSBearings are always measured within the four quadrants of the directional circleBearings are always measured as the angle from the North or South Pole towards either the East or WestBearings cannot exceed 90 degrees

DIRECTIONS and TRENDS

Instructors note Using BLM No. 9 determine the bearings for the

following 8 coursesA,B,C,D,E,F,G,H

DIRECTIONS and TRENDS

AZIMUTHSAzimuths are directions expressed as angles,measured clockwise from North through the full range of the directional circle.Azimuths range from 0-360 degreesThe 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 anotherOn a map there are three primary references that are used to measure direction:True NorthMagnetic NorthGrid North

MAGNETIC DECLINATION

Declination…cont’dTrue North (TN)- The direction of the earth’s North geographic pole. All lines of Longitude meet thereMagnetic 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 westerlyA 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 declinationALL searchers responsible for navigation should check the map each time they use it, and calculate the current declination if requiredThe sample calculation is based on BLM No. 12The diagram indicates the declination was 23 degrees17’ in 1976 and was decreasing 5.4’annually

MAGNETIC DECLINATION

Calculating current declination…cont’dCalculate 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’DSince 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’dNote 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 workWhenever 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’dThe 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’dWith 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 MAG.DEC.17E Azimuth (mag) 094 Bearing (true) 17 E Azimuth (true)______ 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