Transcript Compass “Cardinal Points”

NAVIGATION
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Compass Basics
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The Compass
A compass is an extremely valuable piece of equipment used
not only by hikers and campers, but also pilots in airplanes,
captains of ships at sea, and car drivers everywhere. It is such
a simple but powerful item, everyone should know how to use
one.
Wherever you happen to be on Earth, a compass in your hand
will always point North. Whether you are stranded in the ocean,
caught in a blizzard, or lost in a deep, dark forest late at night,
your compass can always be used to help find the way.
Sure, a GPS is pretty cool, but it needs batteries and a satellite
signal. Not the magnetic compass!
Parts of a Compass
There are many types of compasses ranging from tiny thumb compasses to
complex high-tech gadgets. For most hikers and outdoors adventurers, an
orienteering compass works just great and that is what is described below
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How a Compass Works
There is a huge magnetic field around the earth. It is huge, but it is not
very strong. The magnetized needle in a compass is aligned with this
magnetic field. As the image below shows, the composition of the
earth acts as a huge bar magnet sitting upside down in the middle of
the planet. Since its South end is at the north pole and its North end is
at the south pole, the North end of a compass needle is pulled north.
A compass has to have a very light needle sitting on a pivot that has almost no
friction. This is because the earth's magnetic field is weak and would not be able
to turn the needle.
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Compass “Cardinal Points”
Cardinal Points
There are four cardinal points on a compass - North,
South, East, and West.
Intercardinal Points
The direction halfway between North and East is an intercardinal point and is called NorthEast. The other
three intercardinal points are SouthEast,
SouthWest, and NorthWest.
Secondary Intercardinal Points
Finally, there are secondary intercardinal points halfway between each cardinal point and intercardinal
point. These are North-NorthEast, East-NorthEast, East-SouthEast, South-SouthEast, ... and
so on.
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Compass “Cardinal Points”
Cardinal Point
Secondary
Intercardinal Point
Cardinal Point
Secondary
Intercardinal Point
Intercardinal Point
Intercardinal Point
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Compass Reading - Degrees
Around your compass, there are also numbers and tiny lines. These represent the 360
degrees in a circle that surrounds you no matter where you are. These numbers
match up with the cardinal points on the compass in as shown below.
0
45
90
135
180
225
270
315
Degrees
Degrees
Degrees
Degrees
Degrees
Degrees
Degrees
Degrees
=
=
=
=
=
=
=
=
North
NorthEast
East
SouthEast
South
SouthWest
West
NorthWest
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Compass Reading
Bearings, & Headings
Bearings and Headings basically describe the direction that you would like to travel.
For example, to find that secret fishing hot-spot that you heard was about 200 yards into the
woods at a bearing of 250 Degrees South-West from the parking area . . . You would follow the
steps below.
Step 1
1.. Turn with your compass until the
compass needle is pointing to the
“North” or 0-degree marker.
2.. Rotate the baseplate of your
compass until the “Direction of
Travel” arrow matches to the 250degree mark
Step 2
Travel Direction
3.. Follow the “Direction of Travel”
arrow for 200 yards – and have a
great day of fishing
To return to the parking area . . .
Repeat the same process . . . But this
time, your bearing will be 70-degrees
(250 – 180).
>> Match the compass needle to the
“North (0-degree) marker
>> Rotate the baseplate until the
Direction of Travel arrow matches to
the 70-degree mark
>> Follow the Direction of Travel
arrow back to the parking area
Travel Direction to return to parking area . . . 70-degrees
Compass Reading - Declination
Unfortunately – your compass does not work quite as expected !!!
Earlier, it was described that the earth is like a big bar magnet . . . Except . . . the north end of
the magnet is not actually at the earth’s real north pole. The north end of the earth’s natural
magnet is about 1500 miles below and a bit to the west of the actual or geographic north pole.
FOR EXAMPLE: In the Massachusetts area . . . The difference between the earth’s actual north
pole and the magnetic north is about 15-degrees.
North Georgia difference is about 4º.
This difference is called “Declination”.
Magnetic North Pole
Geographic North Pole
About 15-degrees difference
Magnetic North
(0-degree bearing)
True North (In Massachusetts this is about 15-degrees
to the right of Magnetic north)
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Compass Reading – Declination Adjustment
Whenever directions or bearings are taken from a map, they will always be based on “TrueNorth” (geographic north).
If those directions to that secret fishing spot were based on information from a map . . . you will
need to adjust the “Direction of Travel” arrow for the 15-degree declination by subtracting the
15 degrees from the “250-degree” bearing instruction . . . to a “Direction of Travel” setting of
235-degrees.
Before Declination
Adjustment
After Declination
Adjustment
You can see that the adjusted Direction of Travel is quite a bit different.
Many Orienteering-Compasses have adjustment markings and screws that allow the compass
to be “pre-set” for the declination adjustment for the area where you are traveling
Compass Reading – Declination Adjustment
The map below shows how the Declination varies across the United States.
>> The eastern states require “-” adjustments for declination
>> The western states requre “+” adjustments for declination
Know your Pace
Pacing
In orienteering or treasure hunting (or finding that secret fishing spot), it is often valuable to
count your paces in order to estimate the distance you've traveled in a certain direction.
To determine your pace: Accurately measure a distance - using a 100 yard (300 feet) football
field is perfect.
Walk the length of the field, counting each time your right foot steps down. Or, just your left foot
if you prefer.
Divide 300 feet by the number of paces you took and that is your pace length.
It is a good idea to repeat this in the other direction and take an average.
Example . . .
For a 100 yard (300 foot) distance, your right foot came down 68 times.
So . . . To find that secret fishing spot (200 yards from the parking area) . . . Your right foot would need to come down about 136 times
during your hike. (68 x 2)
Of course, during the hike, there may be hills, trees, swamps and other obstructions . . . So the 136 paces is only a general guess.
if you have traveled 500 paces into the woods and you are not yet fishing . . . It is likely that you have missed your target .
But
Compass Lore
Radio conversation between two ships passing in the night . . .
Voice 1: "We can see your lights and you are on a collision course with our vessel.
Please divert your course 15 degrees to the North to avoid a collision."
Voice 2: "I can see your lights too and recommend you divert your course 15 degrees to
the South to avoid a collision."
Voice 1: "This is the captain of a US Navy ship. I say again, divert YOUR course."
Voice 2: "No, I say again, you divert YOUR course."
Voice 1: "I am the U.S.S. Wolverine, the largest battleship on this ocean. I DEMAND that
you change your course one-five degrees North!"
Voice 2: "I am in the Point Amour lighthouse. Your call, sir."
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Compass Lore
Tate Compass Co.
There was once a couple named Nancy & Mike Tate, and it was their life' s dream to have
a compass company. They finally saved enough money and started the Tate's Compass
Company. Luck was with them, for the first contract they acquired was to manufacture
750,000 compasses for the Boy Scouts. Nancy and Mike worked feverishly day and night
to meet their deadline, & finished just before the Boy Scout Jamboree was to begin.
On the day of the Scout Wilderness hike, each boy scout was given a Tate's Compass to
help them find their way. Unfortunately, it was discovered too late that every single
compass was made with the colored point of the needle facing the wrong way,so when
one was facing North, the needle pointed to the South. Needless to say, all of the boy
scouts got lost & it was the biggest fiasco known in Boy Scout history. The Tate's
compass company went out of business, but from this experience came the familiar
adage...
"He who has a Tate's is lost." (Say it out loud).
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Finding Direction with No Compass
There are lots of ways to find directions if you've lost or
forgotten your compass.
They are great exercises to do just to learn them and have
handy just in case or to impress your city-slicker friends.
These methods can be used to map cardinal directions and
better, but remember that they are not nearly as good as a
compass.
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Polaris . . . the North Star
Find the Big Dipper in the sky.
Follow the edge of the ladle 5 times its length up the edge of the ladle.
The brightest star there is Polaris the North Star which is virtually north.
Cassiopeia is a 'W' shaped constellation across the North Star from the Big Dipper. It's 'W' points
right at the north star
Cassiopeia
North Star
Big Dipper
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Watch Method
In the days of digital watches, this one is fading away.
* If daylight time is in effect, first set your wacth back on standard time.
* Place your watch on something flat with the hour hand pointing to the sun.
* True south is mid-way between the hour hand and the Number 12 on the watch.
* True north is directly opposite.
At 5pm . . .
>> Point the “5” toward the sun
>> Imagine a line between the “5” and
the “12”
>> “South” is mid-way between the “5”
and the “12”
Sun Shadow Method
The sun moves across the sky from east to west and its shadow gradually changes in length which is what
makes this direction finding method work.
* Clear a flat area of dirt or sand. Grass will work, but not as well.
* Find a stick about 2 or 3 feet long and stick poke it into the ground so it stands up.
* Get another small stick or pebble and place it exactly on the end of the shadow line.
* Eat a trail bar or relax for a half hour.
* Place another stick or pebble at the end of the new shadow. If you have time, wait another 1/2 hour and
repeat.
* The line between the two pebbles runs east-west direction with the first mark being west and the second
being east.
* If you are in the northern hemisphere, North direction is perpendicular to the east-west line heading away
from the sun. It's South down under.
.
Star Method
If you can't find the Big Dipper because it is behind a mountain, or behind clouds this method can help if you
can see some stars in the sky:
* Find a tall stick about 3 or 4 feet high and stick it in the ground.
* Sit on the ground by the stick.
•Using another stick about 2 feet long, sight the tops of both sticks to a bright star and stick the shorter stick in the ground.
* Come back in a half hour and notice which direction the star has moved. You may want to check this at 15 minute intervals
for an hour.
* If the star has moved to the right, you are facing south.
If the star has moved Left = facing North
If the star has moved Up = facing East
If the star has moved Down = facing West
* The star will most likely have moved up and right or down and right so you will need to estimate the direction, such as
SouthEast or SouthWest.
Starting Position
Ending Position
Moved Right –
you are Facing South
Ending Position
Moved Up–
you are Facing East
Ending Position
Moved Down–
you are Facing West
Map Basics
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Map Basics
Whether a charcoal and parchment treasure map or multi-colored, plastic-coated, trail map,
maps tell a story of the world around us. Maps help us to locate places, measure distances, and
find where we are on the earth.
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Map Basics
Reading maps is not usually difficult because there are some rules that are generally followed
when creating and reading maps:
North, South, East, and West are the four main "cardinal" directions.
On a map, North is at the top, South at the bottom, West to the left, and East to the right.
Every map has a Map Scale which relates distance on the map to the world. For example, one inch equals one mile.
Using the scale of a map, you can tell the actual distance between two points for real.
Maps use Map Symbols to represent real-world things, such as buildings, trails, roads, bridges, and rivers.
Maps use colors to share more information.
Blue often means water
Green means forest
White means bare land.
A map has a Legend which lists the symbols it uses and what they mean.
A grid of imaginary lines wrap around and over the earth. These lines are called Latitude and Longitude and can identify
the exact location of any point on earth.
Keeping those things in mind, you can read pretty much any map and especially learn how to read a topographic or topo
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map for navigation in the back country.
Types of Maps
There are several types of maps. Each show different information. Most maps include a compass rose, which indicates which
way is north, south, east and west. They also include a scale so you can estimate distances. Here's a look at some different
types of maps.
Climate Maps - Give general information about the climate and precipitation (rain and snow) of a region. Cartographers, or
mapmakers, use colors to show different climate or precipitation zones.
Economic or Resource Maps - Feature the type of natural resources or economic activity that dominates an area.
Cartographers use symbols to show the locations of natural resources or economic activities. For example, oranges on a map of
Florida tell you that oranges are grown there.
Physical Maps - Illustrate the physical features of an area, such as the mountains, rivers and lakes. The water is usually shown
in blue. Colors are used to show relief—differences in land elevations. Green is typically used at lower elevations, and orange or
brown indicate higher elevations.
Political Maps - do not show physical features. Instead, they indicate state and national boundaries and capital and major
cities. A capital city is usually marked with a star within a circle.
Road Maps - show major—some minor highways—and roads, airports, railroad tracks, cities and other points of interest in an
area. People use road maps to plan trips and for driving directions.
Topographic Maps - include contour lines to show the shape and elevation of an area. Lines that are close together indicate
steep terrain, and lines that are far apart indicate flat terrain.
Basic Orienteering Map
Map
Symbols
Map Scale
Countour Lines
(The closer the lines,
the steeper the hill)
Meridian Lines
To line up Compass
Map Symbols
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More Map Symbols
Label
Box
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More Map Symbols
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