Making a Map (Advanced Compass Work)
By Mike Freeman
Objective: Draw a map of the surrounding area.
Bonus Questions!
1. Does the needle on a compass point to True North?
2. Do you know what makes a compass work?
3. Do you know why Maps have to be constantly updated?
Before we start, we need to get set up.
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Look at the X on your map. This will be your starting position. Have you ever seen a map where it
says, “You are here”? Well, for this exercise, we will assume this is where you are standing when
you begin.
Before we decide if this is a good place for our exercise, turn around in a circle and try to spot at
least 3 landmarks close by. This exercise requires that one of these Landmarks must be behind
you, one must be somewhere to your left and the other must be somewhere to your right. In other
words, you cannot use 3 landmarks in the same direction.
Once you are satisfied you have chosen a good spot, place your flag behind your feet. This marks
your spot.
Sighting in an object, the Right Way!
Our first objective is to sight in our landmarks and get the bearing readings from them. You do this just
like you’ve always done before, but before we do, remember; you are trying to earn a Camper patch, so
now we must improve our skills and learn a new advanced way of using a compass. To find a true
bearing reading we will need to know where True North is. Magnetic North is where our compasses
needle points to, but that was only the first step. It is what we learned as a beginner. Now, as
Campers, we are ready to take it to the next level.
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Look at the bottom of you map. You will see something at the bottom that says, “Magnetic
Declination.” The lines above it, tell us the angle difference in degrees, between True North and
Magnetic North. Find the degree reading. What does it say?
Once we know what the “Magnetic Declination” for our area is, we will have to adjust our compass
by that many degrees after we sight in our object the old way. You will always use the old way; you
will just do it a little differently. We will now get our bearings in three steps instead of one.
a. Find an object
b. Sight it in the old way
c. Now adjust your compass the number of degrees to allow for “Magnetic Declination.” Can
you guess which way to turn your housing? Do you adjust right or adjust left? See if you
can guess. (HINT: If the declination is to the left of True North, you add to your number.
If it is to the Right, you subtract) For example, since North is technically 360 degrees, and
our declination is left of True North by 6 degrees, then our True North bearing should
actually be, 366 degrees.
d. Ask you counselor to see if you are right.
Once we understand how many degrees to adjust our compass, we must remember that this
adjustment will apply to all of our bearing readings, whether we’re sighting in an object or just
getting a bearing reading.
Now on your notepad, make a note of your first object with the new adjustment included.
Repeat this process for the next 2 objects.
Stepping out by the numbers.
So you know how to get there, but do you know how long it will take? Most maps include a little ruler at
the bottom called a, “Scale”. The scale means how far a specific measure of distance is. For example,
if it says 1 mile on top of the ruler, and it says one inch on the bottom of the ruler… you guessed it, it
means every inch represents a mile. In our example, we will be scaling it down a bit since we don’t you
wandering off too far. Instead of Miles, we will be using feet.
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7.
Find the “Scale” at the bottom of your map. What does it say?
Now that you know how many feet represent an inch, you need to figure out just how many feet are
between your “X” and your first object. Then you will need to translate that into inches on your
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map. Starting at your flag (Your “X”), take about a three-foot step. Do you know what
measurement three feet is? That’s right, it’s a yard. So unless we want to shuffle our steps one
foot at a time, let’s walk normal and step like our legs are actually longer than a wiener dogs.
How many yards did it take to reach your object? Probably a few yards and a little bit, right? Well
we need to figure out how many feet we walked, so let’s divide the number of yards by 3. Let’s not
forget the “Little bit” extra we had. We need to add that to our number. Don’t you love math?!
Write that down on your notepad right beside the bearing reading you should have already marked
earlier for your object’s bearing. So here’s kind of what your notepad should look like by now..
My Objects
Flag Pole
Picnic Table
Big Oak Tree
Bearing
285
80
190
Distance
45 feet
30 feet
40 feet
Now don’t use my numbers, because I made them up!!
10. Now we come to the last few steps. We need to take our map and do two things
a. We need to orient our map and compass
b. We need to “Plot” our first bearing, in my case the “Flag Pole”.
c. Then we will “Plot” the distance on our map where our object is in terms of distance.
11. Get your map, notepad, and your compass and go to a table to write all of this down.
12. Orient the Map to the Compass. Using the housing of the compass, dial up 360 degrees (North).
Don’t forget to include the “Magnetic Declination”!
13. Orient the Map and compass
a. Lay the compass down on the map and line the edge up with the “True North” arrow.
b. Now turn the map and compass together on the table until “Magnetic needle” lines up with
the “Orienting arrow”. Notice that since we included our “Magnetic declination” into our
bearing reading before we placed it on our map, all we had to do at that point was find
“Magnetic North” by letting the “Magnetic Needle line up with the “Orienting Arrow”
14. Plot the First Bearing
a. Now hold your map in place so that it doesn’t move. If it does, you could throw it off
course and we would have to start over at step 13 again.
b. Using the housing of the compass, dial up the first bearing reading. Don’t forget to include
the “Magnetic Declination”!
c. Hold your map carefully so that it doesn’t move, and place the left corner of your compass
on your “X”,
d. Now, holding the edge of the compass on the “X”, pivot the compass around in a circular
motion to the right or left until the “Magnetic Needle” lines up with the “Orienting Arrow”
e. If you’ve done this right, your Edge of your compass should be pointing at your target,
your bearing reading should still be what you set it on, and your Magnetic Needle, your
Orienting Arrow, and your map’s “True North” mark should all be pointing the same
direction! If not, call a counselor and return to step 13. Otherwise proceed.
15. Plot the Distance
a. Using the ruler located on the edge of your compass, count up the number of inches that
represents the distance of your object in terms of where your “X” is located. In my
example, my first object was 45 feet away. Since our map says that 10 feet represent 1
inch, I need to plot 4.5 inches on my map. I also noticed that my compass doesn’t have
enough inches to reach that far. As a matter of fact, my compass only goes up to 3
inches. So I will make a tiny mark on the map at the end of my compass, pick up my
compass, then place the bottom left corner of my compass back down on my new mark,
then line up my compass with the correct bearing to make sure I am still in line.
b. From there I continue to count from my mark until I have reached 45 feet.
16. There is one last thing. We have to place a symbol there so that we can use it in our Map Legend.
So I am going to draw a little flagpole right where my first object (A Flagpole) is.
17. In order for someone to understand what my symbol means, since I may not be able to draw very
good, I am going to draw that same symbol in the legend of my map with the word, “Flagpole”
beside it.
18. Do the same with your object
19. Repeat that step for your other objects
20. When you are through, turn your paper in.
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Leaders Answers to Bonus Questions:
These are really discussion questions with some very long answers. You can let the boys
break it down into something simpler, but there is some great info here.
1. Does the needle on a compass point to True North?
No. The needle always points to Magnetic North. True North varies depending on what part
of the planet you are standing on. The difference between True North and Magnetic North is
called “Declination”
2. Do you know what makes a compass work?
Do you really want to know?? Here goes…
The Basics
A compass is an extremely simple device. A magnetic compass (as opposed to a gyroscopic
compass) consists of a small, lightweight magnet balanced on a nearly frictionless pivot point.
The magnet is generally called a needle. One end of the needle is often marked "N," for north, or
colored in some way to indicate that it points toward north. On the surface, that's all there is to a
compass.
The reason why a compass works is more interesting. It turns
out that you can think of the Earth as having a gigantic bar
magnet buried inside. In order for the north end of the
compass to point toward the North Pole, you have to assume
that the buried bar magnet has its south end at the North Pole,
as shown in the diagram at the right. If you think of the world
this way, then you can see that the normal "opposites attract"
rule of magnets would cause the north end of the compass
needle to point toward the south end of the buried bar magnet.
So the compass points toward the North Pole.
To be completely accurate, the bar magnet does not run
exactly along the Earth's rotational axis. It is skewed slightly
off center. This skew is called the declination, and most good
maps indicate what the declination is in different areas (since
it changes a little depending on where you are on the planet).
The magnetic field of the Earth is fairly weak on the surface. After all, the planet Earth is almost
8,000 miles in diameter, so the magnetic field has to travel a long way to affect your compass.
That is why a compass needs to have a lightweight magnet and a frictionless bearing.
Otherwise, there just isn't enough strength in the Earth's magnetic field to turn the needle.
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The "big bar magnet buried in the core" analogy works to explain why the Earth has a magnetic
field, but obviously that is not what is really happening. So what is really happening?
No one knows for sure, but there is a working theory currently making the rounds. As seen on the
above, the Earth's core is thought to consist largely of molten iron (red). But at the very core, the
pressure is so great that this super hot iron crystallizes into a solid. Convection caused by heat
radiating from the core, along with the rotation of the Earth, causes the liquid iron to move in a
rotational pattern. It is believed that these rotational forces in the liquid iron layer lead to weak
magnetic forces around the axis of spin.
3. Do you know why Maps have to be constantly updated?
I bet you said yes because of the obvious answer such as the landscape changes due to
progress, weather erosion, earthquakes, volcanoes, parking lots, global warming and kids.
Yeah that was my answer too. But that’s the easy answer. There is still one more reason
our maps have to be changed.
You remember that Red Hot Molten stuff we talked about earlier? Well it moves. Of course
you or I will not notice it too much in our life time, but every 50 years or so, that gooey stuff
does this shape-shifting thing and whamo! the declination shifts a degree or two (give or take
a few hundred miles). What does this mean? It means Job Security at the BLM (Bureau of
Land Management) Yep, we’ve got government guys that spend your hard-earned tax
dollars remapping the all of the changes in the landscape as well as penciling in that new
very important magnetic number called “Declination” (The difference between True North and
Magnetic North).
Declination is an important part of map reading. In the southern states, close to the
Mississippi river, you’re looking at about a 4 or 6 degree declination, depending on what
decade you finally decided to read this document. 4 degrees might not sound like much, but
if you plot a course without considering the proper declination, you’ll soon start adding feet,
yards or even miles to your error, depending how far you travel. If you did this by boat or
airplane, it could be really bad. Suddenly your flight from Memphis to St. Louis Missouri ends
up in Louisville Kentucky (home of the Wildcats); and who wants to go there? Of course,
leading your RA rug-rats past their campsite by only a few hundred feet can be bad too. Now
you will immediately start adding feet, yards or miles, depending on how stubborn you are,
away from your destination in the opposite direction. Let’s see you correct that boo-boo
when you finally decide to turn around…. All I can say is, don’t use bread crumbs, bring
plenty of trail mix and don’t forget your manual on “What to do when lost”.
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