Navigation – Basics of the map key

Navigation – Basics of the map key

Difference between topo and other map types and the best ones for navigating in foot versus vehicle

Compass do’s and don’ts and nomenclature. How to use a sighting compass

How to orient yourself to the map

How to figure out your location

How to get from A – B

Final thoughts and advice.

This will be the first 4 days the fifth day is a practical application tip or two.

Map and compass use

There are a few important things to understand when you first look at a map.

1. Scale?

How big is the area the map represents? Most modern maps have distance scales on the bottom of the page or in the back of a book of maps. They usually relate an inch or centimeter on paper to the equivalent distance on the ground (this measurement does not take terrain into consideration).

2. Legend and key

Usually located in the bottom corner of a map, the legend or key will explain what each symbol on the map represents. It also contains important information like declination and elevation line value.

3. Map type

Topographic maps (show terrain differences with elevation lines) vary differently from road maps and satellite maps. Make sure you have the right map for your objective.

Road maps are designed for travel by vehicle and prioritize road identifications, this may seem like a no brainer but a map looks like a map when you are in a hurry.

Topographic (aka topo maps) will show roads but identification is a low priority. They show terriain by marking lines at specific elevations. They also show water ways, be sure to check the legend as some water ways are seasonal and will be marked as such. It’s important to find the value of each elevation line (does each line represent a rise/fall of 10 feet or 40 feet?). The farther the elevation lines are from each other, the more gentle the slop is. The closer the lines are, the steeper the slope. You can calculate the slope on paper by filling in the Rise/Run equation. For example, pick an area on a map and measure the distance (using the scale to determine feet, not inches on the map) and this gives you the “Run”. Now measure the elevation change over that same distance, this gives you the “Rise”. So, if the elevation increases by 30 feet in the 100 foot distance on the map, you have a 30% slope. Here is a pet peeve, a 100% slope is not verticle. A 100% slope would be if the elevation increased by 100 feet over that 100 foot distance, this is actually only a 45 degree angle. A 200% slope would be a 200 foot elevation increase over the 100 foot distance, still not vertical. Not a truly important thing to know but will keep you from sounding like an idiot when discussing this with others.

Satellite maps are not commonly used by themselves. They will not have any road markings or show terrain values. Simply put, they are digital pictures of the landscape from above. One benefit of satellite maps is the ability to show differences in vegetation. You can tell the difference between a brush field, a thick or scattered forest and a meadow. These maps can often be acquired on clear plastic and are a great supplement to another map of the area AS LONG AS THEY ARE THE SAME SCALE!

4. Compass

A compass works by floating (via water or balance on a post) a magnetically charged metal so it can freely spin to align itself with magnetic poles. The north post is usually identified by being brightly colored and red is the most common.

Declination is crucial! Since a compass is magnetic, it points to magnetic north, not true north. Im not going to get into the physics of this relationship but the magnetic poles constantly shift. You have to accommodate for this via “declination”, simply adjusting your compass to accommodate this difference in angle between you, true north and magnetic north. The declination setting of your compass varies by your location and you should double check for declination changes every few months and write the current settings somewhere you will find it when you need your compass. Save yourself some grief and $, if the compass you currently have or the compass you are looking into buying does not have the ability to adjust declination, get rid of it or don’t buy it. Yes, you can calculate the difference on the fly but the less you have to remember the better. Also, keep in mind that any ferrous metal near the compass with cause inaccurate readings.

How to orient your map:

I going to assume we are using a topo map for foot travel. For this you will need a compass with a square base and you will need a flat surface to put your map on. Modern maps will usually have a declination adjustment on it but check the date on the map and correct this with current information, I have seen declination settings change a full degree in 2 years. Once you have your compass set with the correct declination, turn the dial so north is lined up with the bearing line on your compass (this line should be easily identified and parallel with the side of your compass base). Once you have your compass pointing to true north, place it on your map so the outside edge of the map is parallel with your compass base and rotate your map until the top of the map is pointing north. Secure your map so it wont move in the wind and youre done.

How to find your location on a map:

This can be very difficult if you are in an area with minimal terrain. You have to find a terrain feature that you can identify on a map like a tall mountain, a river bend, a meadow or cliffs. You needs at least 2 identifiable features to get a general idea of your location but three (hence the term triangulation) will do much better. Once you find something you think you have also found on the map, use your compass (which you set the declination on and used to orient you map) to get an Azimuth (its location on the degrees of the compass in relation to you) by pointing the bearing arrow of your compass at the object and spinning the dial of your compass until the north end of the needle is in the box that identifies noth on the dial. The degree that is at your bearing arrow is the Azimuth. Write the azimuth down in case something gets moved accidentally. You know the object you just shot an azimuth to, find it on your map. Once you find it, keep your compass lined up and place the edge of its base on that object on the map so you can draw a line in the direction of the reverse azimuth. Draw this line on your map, using the edge of your compass as a ruler, away from the object back towards your location. Do this same thing with another object (not along the same line of sight as the first object) until the lines cross. If the lines do not move towards each other you have not found the right location of the object on your map or you are using the wrong azimuth. Once again, three objects will give you the best accuracy.

How to use a compass to travel to a specific location:

If you know where you are on the map and you know where you need to go on the map you can get a bearing or heading to follow. Seems easy on paper but add vegetation, hills, water and other obstacles and it gets a lot more difficult. The easiest way is to pick an easily identifiable feature (large tree, rock, river bend, ect) somewhere along the bearing you need to travel. Walk to it and then re check your bearing and find a new object to walk to. This saves you from trying to walk in a straight line and constantly look at your compass at the same time.

Last thoughts on compasses.

You get what you pay for in a compass. The $2 ones are next to worthless . $20 is a fair price for a compass that will work in a pinch if it has declination adjustments. Its best to get one with a sighting utensil (so you can get more accurate readings) and even better if it has an attached mirror for making dial adjustments while sighting and using as a signal mirror.

GPS

This culture is increasingly dependent on technology. A handheld gps is a great tool and can make your life easy when you are out in the woods, no need to walk in a straight line, accurate location coordinates, distance and elevation readings and some even have a panic button to send your location to friends or family if you are lost. However, these luxuries only work if it has power and satellite signal. It only takes a small slip of attention to forget to change or bring batteries and you only have to trip and smack these things onto one rock for them to be a brick, trust me. If you have the choice, take a gps with you but don’t let it replace your map and compass.

“WHY NOT GPS? I had the same thought when reading these lists- aside from the fact that it runs on batteries it is a greatly dependent system. The satellite constellation and the ground based WAAS stations are dependent upon a working infrastructure and stability. Who has trouble surviving when everything is working right? If the SHTF scenario is ugly enough that GPS unit is a liability if anything. It can be used to track you, It can go offline in a second, or it can be used to give erroneous information-It’s actually in the Federal Aviation Regulations that the US gov reserves the right the distort the data as it sees fit “in the interest of national security” and we all know what a rabbit hole that is.”

Here are a few compass suggestions:

Huntington MG1 Military Bearing / Lensatic Compass

https://amzn.to/2Ks9Vek

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Suunto MC-2 Compass

https://amzn.to/2jgyG0C

This is the compass I’ve always used and prefer. The mirror let’s you see the compass face while shooting an azimuth. It also works well as a signal mirror.

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Suunto A-10 Compass

https://amzn.to/2rb44kM

Covers the basics

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Avoid going this cheap!!!!

Allen Company Pocket Compass with Lid

https://amzn.to/2JC0h7m

I hope this helps you discover the basic keys to exploring your world and avoid getting lost.

A special thanks to BroTactics for writing this. He’s seen even more of the backcountry than I have!

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