Land navigation with a compass and a map has become a lost art in many places as it has been replaced by smart phones and GPS devices. But what happens when the batteries die? How will you find your way to your destination or to your base camp?
There are many different aspects to navigation, you must determine the units you will use, the compass you will use, the instruments (protractors, triangles, rulers, etc...), and maps in order to even begin your travel plans. Then knowing how to plot your trip correctly is an art, not to mention the execution in the field of the plot you created prior to your trip. With all that said it sounds complicated right? Well fortunately it isnt as complicated as it sounds. Here are some brief explanations of common terms and links to useful tools for you in the field and at home to plot your trip.
Understanding Latitude and Longitude
Every location on earth has a global address. Because the address is in numbers, people can communicate about location no matter what language they might speak. A global address is given as two numbers called coordinates. The two numbers are a location's latitude number and its longitude number ("Lat/Long").
Using Lat/Long is different from using a street address. Instead of having a specific street address, Lat/Long works with a numbered grid system, like what you see when you look at graph paper. It has horizontal lines and vertical lines that intersect. A location can be mapped or found on a grid system simply by giving two numbers which are the location's horizontal and vertical coordinates; or, to say it another way, the "intersection" where the place is located).
Horizontal mapping lines on Earth are lines of latitude. They are known as "parallels" of latitude, because they run parallel to the equator. One simple way to visualize this might be to think about having imaginary horizontal "hula hoops" around the earth, with the biggest hoop around the equator, and then progressively smaller ones stacked above and below it to reach the North and South Poles. (Can you think of other ways to visualize the parallels of Latitude?) Think about having imaginary horizontal "hula hoops" around the earth, with the biggest hoop around the equator, and then progressively smaller ones stacked above and below it to reach the North and South Poles Latitude lines are a numerical way to measure how far north or south of the equator a place is located. The equator is the starting point for measuring latitude--that's why it's marked as 0 degrees latitude. The number of latitude degrees will be larger the further away from the equator the place is located, all the way up to 90 degrees latitude at the poles. Latitude locations are given as __ degrees North or __ degrees South.
Vertical mapping lines on Earth are lines of longitude, known as "meridians". One simple way to visualize this might be to think about having hula hoops cut in half, vertically positioned with one end at the North Pole and the other at the South Pole. Visualize hula hoops cut in half, vertically positioned with one end at the North Pole and the other at the South Pole. Longitude lines are a numerical way to show/measure how far a location is east or west of a universal vertical line called the Prime Meridian. This Prime Meridian line runs vertically, north and south, right over the British Royal Observatory in Greenwich England, from the North Pole to the South Pole. As the vertical starting point for longitude, the Prime Meridian is numbered 0 degrees longitude. To measure longitude east or west of the Prime Meridian, there are 180 vertical longitude lines east of the Prime Meridian and 180 vertical longitude lines west of the Prime Meridian, so longitude locations are given as __ degrees east or __ degrees west. The 180 degree line is a single vertical line called the International Date Line, and it is directly opposite of the Prime Meridian.
To understand declination you must first realize that there are two North Poles. There is a True Geographic North Pole at the top of the world, and a Magnetic North Pole. The Magnetic North Pole is always moving. It has been as much as 1,200+ miles from true north, but in 2005 is only around 500 miles from the True North Pole.
We typically say that a compass points to Magnetic North, not True North. Technically, that is not exactly true. The compass actually points in the directions of the horizontal component of the magnetic field where the compass is located, and not to any single point. Knowing the difference (measured in angular degrees) between true north and the horizontal trace of the magnetic field for your location allows you to correct your compass for the magnetic field in your area. This angular difference is called your declination.
Declination varies from 0 to 30 degrees in most populated regions of the world. These declination values usually change slightly over time, as the earths plates shift. The actual value of declination and its annual rate of change for your area will usually be shown on your map. This will be expressed as either an Easterly or Westerly declination, depending on your location.
The "QUICK MATH" for declination in the field is:
Magnetic North is 10 degrees west of true north, to correct a TRUE bearing (e.g. 30) to MAGNETIC, We need to rotate counterclockwise to correct.
So DECLINATION is ADDED to the magnetic bearing 30 + 10 = 40
Magnetic North is 10 Degrees East of True North, To correct a TRUE bearing (e.g. 30) to MAGNETIC, We need to rotate clockwise to correct.
So DECLINATION is SUBTRACTED from the true bearing 30 - 10 = 20
In order to successfully triangulate, known features must exist on your map. In other words, you must have some idea of where you are or be able to identify a well-known landmark from your viewpoint. Known, or visible points such as mountains or valleys can help in identifying your location for triangulation as well.
Universal Transverse Mercator
The UTM (Universal Transverse Mercator) system is a system of coordinates that describes position on a map. GPS receivers can display locations in UTM coordinates. Most maps, especially those for hikers, display UTM coordinates. They are widely used by Search and Rescue operators and are even becoming more common in guidebooks.