How To Use A Compass To Draw A Circle

Google Maps and GPS are amazing. But do you know how to utilise a map and compass to navigate if you lot suddenly couldn't use (or trust) whatsoever electronics? Fifty-fifty with modern applied science, people go lost and die all the time — rescue workers even have a name for it: death by GPS.

Maps and compasses are deceptively powerful tools. Simply they aren't equally confusing or complicated as you might think, and using this simple guide to acquire the basics might salvage your life in a wide range of survival scenarios.

More: Review of the all-time compasses

This 1 folio guide covers the basics you would larn in a weekend navigation course. Nosotros'll focus on the techniques of using a map and compass in four examples: how to orient a map to Truthful North, how to plot a class, how to walk that course ("shoot a bearing"), and how to figure out where yous are on the map ("angulation").

In this guide:

• Why y'all should larn how to use a map and compass
• Compass basics
• Map basics
• First skill: Orient a map using a compass
• 2nd skill: Plot a course
• Third skill: Travel by post-obit a compass bearing
• Fourth skill: Effigy out your location on a map

Why you should trust us

In 1991, I began my preparation as a Usa Air Forcefulness South.East.R.Due east. Specialist (Survival, Evasion, Resistance, Escape). After becoming an teacher, I taught air crews how to survive if they became trapped backside enemy lines. That often involved navigating in unknown terrain with limited resources or assistance.

I'1000 now the caput teacher at a survival grooming school and accept taught countless beginners how to navigate in survival situations. On the side, I'm also a consultant for survival Television set shows like Science Aqueduct'southward Hacking the Wild.

• Website

Jessie Krebs. U.S. Air Force SERE Specialist and Instructor (Survival, Evasion, Resistance, Escape). Runs survival training school. Consultant to TV shows like Hacking the Wild and Kicking & Screaming.

• Twitter

Founder of The Prepared. Prepping for 16 years and didactics others for 12. Background mostly in Silicon Valley and regime. Advised White House and DOD on emergency technology (eg. I co-founded the Defense Innovation Unit) and related issues like economic decline. Have worked in 30+ countries on everything from climatic change to social unrest.

Why yous should learn how to use a map and compass

The filigree goes down, your batteries dice, your machine gets stuck, and at present you're stuck in the wilderness. In my work as a survival instructor in the military and civilian world, I've heard lots of stories of people getting lost and dying — and sometimes their bodies are plant pretty close to a trail.

Sometimes GPS can lead you downward a path that is technically correct but a very bad idea — rescue workers call this "death by GPS", and it's the cause of a growing number of emergencies.

For example, in the summer of 2009 a nurse and her six year erstwhile son were driving through Death Valley National Park. Their GPS took them downward a little used dirt route. The rangers found them a week later, but unfortunately the child died.

Or the family unit that went down the wrong road and was stuck in the snow for two days in Bryce Canyon National Park. Or the couple driving from Canada to Las Vegas who took a GPS shortcut in the dark, yet subsequently a iii week rescue effort were declared dead.

Fifty-fifty if armed with only a compass, a lot tin can exist achieved if yous keep a cool head. Nigh people can figure out the bones NSEW directions in the daytime, and if you're lost in a more often than not familiar surface area like your favorite park, having and using your compass can make a real departure in how well (or if) you survive.

Compass nuts

• Magnetic N seeking arrow. This is the chief arrow you're all familiar with. Information technology spins effectually to discover Magnetic North. The tip is ordinarily red, which we use afterward with the "red in the shed" method.
• Direction of travel arrow / lines. This is a stock-still line or arrow that sits outside the spinning compass compartment. It points in the same direction the concrete front of the compass is pointing.
• Stationary index line. This is a thin line that points in the same direction equally the management of travel line. Information technology doesn't spin, but it is in or virtually the spinning compartment.
• Rotating bezel ring. The rotating ring effectually the Magnetic North seeking pointer that has the caste numbers from 0 to 360.
• Orienting arrow / lines. Built into the face of the compass so that information technology points to 360 degrees on the rotating bezel ring. The orienting arrow and lines will point wherever you spin the bezel. The space inside the arrow is the "shed".
• Base plate and straight edge. Whether it folds or not, a practiced compass can lay flat and has a long directly edge so you can create lines and have measurements on your map.

Magnetic North vs. True North and how the difference affects navigation

You lot may already know that a compass doesn't point to True North (the Northward Pole) and instead points to the Magnetic North Pole. Just does this matter for elementary survival?

What really matters for navigation is the bending of difference between the two poles from where you're physically continuing.

If y'all drew two lines from your position to both poles, the degree of difference between those two lines is called the magnetic variation, a.chiliad.a. magnetic declination.

For about of America the difference is around 5 degrees. On the west coast and in Alaska, the difference tin can exist 12-xv degrees. If you travel but a few miles, even small-scale differences of a few degrees between True and Magnetic can take you way off course.

Considering the Earth is a big magnet with a complex magnetic field, these forces are moving all the time. The two poles are about 800 km (~500 miles) apart. The magnetic pole has moved nearly 1,000 kilometers (621 miles) n in the terminal 150 years, and it's accelerating.

via NOAA

This animation shows the difference in degrees at various parts around the earth and how they've changed over time:

Because of those variations, maps are drawn to Truthful North, not Magnetic North. Then you lot accept to reconcile for this difference when using a compass and map together, depending on where yous are.

You should await upwardly your declination on NOAA's website. Some example results effectually the Us:

Los Angeles, Kansas City, and Tampa – discover how information technology changes west to east.

Another way to visualize this: imagine you're looking direct at the Due north Pole from where you're standing. From that betoken of view, the Magnetic Pole is going to be on either the westward or e side of your line of sight to True North.

The declination reading is more than only a number — for case, the NOAA reading for Los Angeles says "12 degrees east" and Tampa says "v degrees west."

That means that when y'all're in LA, Magnetic Northward is 12 degrees to the eastward (or correct) of True North. For Tampa, it's v degrees to the west (or left).

You lot'll need to add or subtract the declination number from 0/360 degrees (same matter) on your compass. If your declination is e, you decrease the number. If w, add together.

A simple trick we used in the war machine to remember whether to add or decrease was the maxim, "East is To the lowest degree and West is All-time." If you need to look e to see the magnetic pole yous subtract the number. If y'all look w, add the number.

Imagine you want to walk from Los Angeles to the True North Pole. The compass would be trying to take yous 12 degrees in the wrong direction to the eastward/correct. So you would actually want to follow 348 degrees on your compass.

We know this can be a little catchy to read, so visualize it a few times. It'll sink in.

Map basics

Nosotros have an astonishing gift in modern maps. There is a huge wealth of information broiled into them, and then let'southward learn the basics.

Scale

Maps obviously come up in different shapes and sizes. Two different maps on the same sized canvas of newspaper might but cover your town or the whole state. Imagine you're in a hot air airship looking down — the college you go, the more you lot can see merely the less detailed things get.

The scale is 1 of the beginning things I look at when I pick upwards a map. The scale tells yous 2 very important things with one gear up of numbers: about how much area does the map prove, and how much particular of that area will it show?

The numbers are gear up like a ratio. 1:50,000 is considered a "large" scale because things await large, every bit if your hot air balloon was only a few hundred anxiety to a higher place the footing. A ratio of 1:200,000 is "small-scale" because things on the ground would wait small, equally if yous're looking down from an airplane.

Map scale is important in survival scenarios. If you're traveling quickly in a machine, you don't intendance much nigh the details of the little creeks you drive over. But if you're on foot or you take to leave the primary roads in an emergency, those larger scale maps come in very handy.

You lot'll accept to use personal judgement when buying the map(s) that make sense for you. If yous want to err on the side of circumspection, get multiple big scale (i.east. detailed) maps that cumulatively cover where y'all're most probable to become.

Legend

Every decent map should accept some kind of fable. The fable explains everything you need to know virtually how the map was built, similar what the different symbols, colors, and textures hateful.

Legends as well notation the map's scale, which explains how much country area is covered in the map.

If the map has grid lines or topographic contour lines, the measurements will be explained in the legend. For example, it might specify that 1 of the grid blocks overlaid on the map is equal to i mile and that the elevation contour lines are for every 100 feet.

If yous're buying a map, look at how detailed the legend is. Does it requite yous the right information, like map scale, symbol charts, and magnetic declination? Was information technology published in 1984 and likely inaccurate today?

Topographic maps

via Wikipedia

Topographic maps are typically more useful than plain route maps because they show the lay of the country and other geographical features in addition to the normal manmade features and roads.

They practice this by turning a two dimensional map into a three dimensional 1, typically by using contour lines to show terrain features. A contour line is a line of equal elevation, meaning everywhere a single contour line touches is the same elevation. The fiddling numbers in the lines, like the 800, 900, and 1000 shown shown above, are the elevation at that line.

Imagine sitting in a bathtub and slowly bringing your closed fist up out of the water, knuckles upward. Let'south say when the topmost knuckle is a quarter inch higher up the waterline, yous use a pen to draw a circle around your knuckle wherever the air and water come across. And then you lift your fist some other quarter inch and make another line right wherever water and air see. Practise this several times until your fist is out of the water. Your fist now has multiple parallel lines each a quarter inch from the other.

Now open your mitt and lay it flat, palm down. You've simply taken something 3-D (your fist) and made it 2-D (the apartment image on the back of your hand).

A map with contour lines will have a "contour interval" listed somewhere in the map legend. On very large scale maps (1:30,000) that show a lot of detail, this interval may be anywhere from 20 to lxxx anxiety. On small calibration maps (1:150,000) that give a high bird's eye view, it may be fourscore to 200 feet.

Every fifth contour line is chosen an "index line" that is a petty thicker than the others. It acts the aforementioned as any other profile line, but gives you a way to count up elevation rapidly. Like old schoolhouse hash marks in groups of five.

These lines assist you visualize features and steepness. In the bathtub fist example, the start circle y'all drew around the tip of your knuckles would look like a closed circle when you lot lay your hand flat. That closed circumvolve shows you lot that it'due south the pinnacle of a hill or mountain.

When profile lines are very shut to each other, that means the acme is changing quickly in a small amount of horizontal infinite. If information technology takes three miles to go from 2,000 to iv,500 feet, that's a pretty easy hike. But if information technology but takes half a mile to get from 2,000 to 4,500 feet, y'all're in for a steep climb.

Nautical maps

via UK Admiralty

If you live near water, and especially if a boat is office of your emergency planning, be sure to accept a practiced nautical map. It shows water depth, currents, hazards, ports, docking areas, distances, and a whole slew of other information. Think of them similar a topographical map for large bodies of water.

Latitude and Longitude coordinates

0° Longitude is the Greenwich meridian line. 180° is the international date line. via Wikipedia

Nosotros don't use coordinates in this lesson, but we do reference things like Longitudinal lines. A lot of people have a difficult time remembering how latitude and longitude coordinates piece of work. Some tips:

• Think of a ladder. Ladders are virtually the rungs you step on to climb. Ladder sounds kind of similar breadth. Latitude = ladder steps = horizontal lines.
• The more than steps yous take up the ladder, the higher you are going in latitude. Because you lot climb up the ladder, if you were halfway between the equator (0 degrees) and the North Pole (xc degrees), you would be at a latitude of 45 degrees North.
• Longitude is the long role of the ladder. It'due south a long way from pole to pole. Those lines run vertically from pole to pole.
• In football, a lateral is when you throw the ball to the side, or horizontally. Horizontal lines. Lateral = latitude.
• If weightlifting, a lateral pulldown is a horizontal bar yous pull downward with your hands.

1. How to orient a map using a compass

Whenever you're using a map, it's very helpful to start by orienting the map so information technology fits the state. It just makes things neater and easier to effigy out. This besides accounts for magnetic declination, so whatever readings you accept afterward are already corrected.

To become the map as accurately oriented as possible, yous'll employ the compass to turn the map until the NSEW directions on the paper map line up with the actual NSEW directions from where you're standing.

Some advanced compasses have a built-in magnetic declination adjustment, then you can fix it once for your location and and then forget virtually information technology. Nosotros're ignoring that feature for this guide since many compasses don't have information technology. And then y'all'll need to know the declination number for your area, either from your map or from NOAA.

1. Start by eyeballing it. Look effectually for any like shooting fish in a barrel landmarks, like a lake or tower, and roughly rotate your map to fit your bespeak of view.
2. Rotate the compass bezel ring so that the stationary index line is matched with your Truthful Northward bearing. In our video, the map is for an area of Washington State, where the current declination is effectually 15 degrees east. Which means True N is at 345 degrees.
3. Align the left direct border of the compass with the left (west) border of the map. The direction of travel pointer on the compass should be pointing to the north end of the map.
4. Concord the compass and map together in a manner that keeps these edges lined up for the next pace.
5. Rotate the unabridged map and compass together until the N seeking arrow lines upward with the Orienting arrow. This is often called putting "cerise in the shed." Red is the Northward seeking pointer (because it's usually a red colour) and the shed is commonly the space between 2 principal orienting lines inside the bezel ring.
6. It's helpful to put something heavy on the map corners to keep it from moving.

2. How to plot a course

Sometimes it's proficient plenty to know "I demand to become e to get to the lake" — but sometimes you need a more than precise heading.

In the military, we teach a six point checklist. Even after 25 years of off-trail hiking, I notwithstanding use some course of information technology in my head or on paper. I might skip pace #5 because I'g enjoying the journeying and don't care well-nigh time.

1. Find the direction, chosen a heading or begetting, from the starting point to the destination.
2. Determine course distance.
3. Evaluate the terrain and path.
4. Estimate the pace count.
5. Estimate time of arrival (ETA).
6. Know what the goal looks like.

Step 1: Detect the bearing

Let'southward plot a course on this Washington State map from the campground on top of Old Rule Mountain to a nearby spring.

At this location, the magnetic variation is 15 degrees East, which means True North is at 345 degrees. I double check that my map is correctly oriented.

To notice my heading from the campground to the bound, I place the directly edge of the compass along that line.

The destination should be towards the front of the compass, so the direction of travel arrow is pointing in the direction you lot want to become. If the altitude is and so long that the edge of your compass only covers a portion of the length between the 2 points, consider breaking your course up into waypoints.

I move the bezel ring until the orienting arrow exactly outlines the Magnetic North seeking arrow (ruby-red in the shed). And then I read the heading from the stationary index line. In this case it reads 271 degrees. That means my destination is 271 degrees from my current location.

Step 2: Determine course distance

The map fable tells me that each filigree square is 1 kilometer. Using the measurement ticks on my straight edge, I can tell this straight line grade is three.nine km (ii.4 miles). I even fabricated little arrow marks with the cherry-red marking at each kilometer.

Another trick is to use something pocket-sized, like a bract of grass that you tear to the proper length based on the scale in the map'due south legend. If the blade of grass equals 1 mile, that makes figuring out the form distance much easier.

Stride 3: Evaluate the terrain

What will y'all see as you walk? Will you exist going uphill or downhill? Will you cantankerous a stream? Passing something expected (like a lake or boondocks) halfway through your journeying tin remove a lot of anxiety.

It looks similar my campground starting point is at the peak of a hill. Which makes sense since it'southward chosen Lookout Belfry.

Equally I follow forth the path, it seem like the beginning volition be pretty steep downhill. Over time it will flatten out, but I'll exist going downhill most the whole fashion. There might be a small-scale stream along the style. Towards the stop of the path, there is a small finger ridge that goes upwards a few hundred feet and then down again to my destination.

Step four: Estimate pace count

A step is two steps. Every time the same human foot hits the ground again, that'due south a pace. There's a reason the armed services uses paces — they're easy to count while walking and can assistance if the terrain is characterless or y'all tin can't meet well.

Nearly people conveying a pack will count 600-800 paces for a kilometer on flat terrain with niggling vegetation to negotiate; 800-i,000 on moderate terrain; and up to about 1,200 for actually steep or thickly vegetated terrain.

If yous want to become serious, measure out your personal pace count. Mensurate out i/10th of a kilometer (nearly 328 feet) or i/20th of a mile (nigh 264 feet), whichever is more than familiar and comfortable to yous. At present walk it out counting your paces. Try information technology with and without a pack on, uphill and downhill, walking fast and slow, hyped up or relaxed, etc.

Even though the path will be by and large downhill, because in that location are some steep parts and probably some vegetation, I gauge about 950 paces per kilometer. Which ways the whole trip volition be nearly iii,800 paces.

Pro tip: experienced navigators use a bracelet of petty beads or some other pocket-sized physical thing to continue track of paces. You move the beads to keep track of how far y'all've gone, and so you lot don't take to worry near counting large numbers or forgetting along the way.

Pace 5: ETA

In that location are some rules of thumb to summate how long a hike will take depending on altitude and terrain. The popular Naismith's rule estimates 1 hour for every 3 miles of horizontal distance, plus 1 hour for every 2,000 feet of ascent.

Based on that rule and my personal feel, I estimate this course volition take 80 minutes.

Step 6: Know your goal

What does your destination look like? How will you know you lot're at that place? How volition y'all know if y'all passed/missed it?

I can see that my destination has a jump in a shallow drainage in the southwest corner of a modest narrow meadow and some hills to the Due east. There may exist a jeep trail running North-South just earlier the goal. If I miss information technology, the terrain will become less steep for a few hundred meters and so drop off very steeply until I hit some power lines forth a creek and a major route a few hundred meters across them.

3. How to employ a compass to walk in the correct management

Standing the example from plotting a course, I know that I need to walk with a bearing of 271 degrees. To exercise that, I rotate the bezel ring until 271 is over the stationary alphabetize line.

Holding the compass with the direction of travel pointer pointing straight ahead of me, I'll plough my whole body with the compass until cherry-red sits neatly in the shed. That means everything is lined upwardly and I tin follow the direction of travel pointer.

The best thing to practise is wait where the travel pointer points and pick an easy to see object in its path. That way yous tin let the compass dangle and keep your head upwardly while walking. When you reach that object, pick up the compass and do it again. This is called "point to point" navigation.

You might exist wondering if you lot need to readjust for magnetic declination now that you've taken the bearing off the map and are traveling. The good news is no, it's simple and already baked in. That's the value of orienting the map to the terrain. Any math y'all did after that orientation is already corrected.

4. How to discover your location on a map

Plotting a course is easy when you know where you are and where y'all desire to go. Only what if you don't know where you lot are at the kickoff or get lost along the way?

Using an advanced skill called angulation (which you might have already heard of via the discussion "triangulation"), you can use the compass and visible landmarks to figure out where you lot are with more than accuracy than just eyeballing it.

1. Endeavor to compress the surface area on the map of where you lot might exist. It's easier to figure out where you are if the possible area is only the size of your fist on the map. Think about where you've come up from. Did yous cantankerous any roads? Go past a large mountain?
2. Assuming your map is oriented to the land and True North, anchor it so information technology doesn't move.
3. Look around you for unique landmarks, like an obvious hill or belfry. Tin you correlate them with what you run across on your map? The points you reference with your compass in the next steps need to be the same points you reference on the map. If you need to, find a better position and look for more than unique landmarks.
4. Next, notice the bearing between yous and that landmark. Agree the compass in front end of yous and point the direction of travel arrow at a very distinct office of the chosen landmark, similar the very top of the mountain.
5. Hold the compass steady and rotate the bezel ring (and thus the "shed" inside it) until the north seeking pointer fits inside the orienting line/arrows (carmine is in the shed). Exist as precise as you lot can.
6. Read the number over the stationary index line and recall it. Let'south imagine it says 254 degrees. That means the bearing from you to the landmark is at 254 degrees.
7. Go dorsum to the map. Put a betoken on the directly edge about the forepart of the compass over your landmark point. That corner is a pivot betoken, and yous elevator and rotate the whole compass around it until blood-red is back in the shed.
8. The direct border of the compass has now made a line extending from the landmark through all the possible areas that would show a 254 degree bearing from that point to the landmark.
9. If possible, use a pencil to trace that line.

This is what it looks similar when I utilise my compass on the oriented map to draw the line from the landmark (the circle on the left):

I knew that I needed to find the line that shows 254 degrees to the landmark, then I rotated the bezel band until 254 was under the alphabetize line. I put the corner of the baseplate on peak of the landmark, creating a pivot signal, then I physically rotated the whole baseplate around that pivot indicate until red was in the shed.

X marks the spot! Whether yous have 2 lines or five, wherever they intersect is your general location.

The more than landmarks you do this with, the more accurate your position becomes. Two lines is biangulation, 3 is triangulation, etc. When picking second and third landmarks to use, endeavor to pick points that are around threescore degrees away from the other. That way, your X is more substantial and authentic.

If yous use three or more points, and the triangle shape created is larger than the tip of your pinky, you lot probably fabricated a mistake when translating the landmark in real life to the landmark on the map. In other words, the mountain you thought you lot were looking at is non the same mount you drew the line from on the map.

Source: https://theprepared.com/survival-skills/guides/learn-compass-map/

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