To calibrate a compass properly, you must understand that magnetic north and true north are not the same directional value. Aug 19, 2017 this is a video summary of the article here on how to buy a compass. Using compass orientate a map and use a draggable rotating animated compass to read a compass and map route bearings. Rather, it aligns itself with the direction of the earths magnetic field, showing magnetic north. The difference between magnetic north and true north is called the angle of magnetic declination, or simply, the declination. Maps are always based on true north south lines at the edges. True north also called geodetic north is the direction along earths surface towards the geographic north pole or true north pole geodetic north differs from magnetic north the direction a compass points toward the magnetic north pole, and from grid north the direction northwards along the grid lines of a map projection. Did you know that most compasses dont actually point to the north pole. In the worlds of sailing and aviation, though, navigation can get a little more complicated. Declination is positive east of true north and negative when west. When you face true north, magnetic north is going to be left, or west, of you by about 14. N on your compass points to true north when you box your needle have the. True north, the one that is marked on the map, refers to the north pole, where all the longitudinal lines on the map meet.
How to calibrate a magnetic compass gone outdoors your. If you want to get from a point at the bottom of a map to one at the top, you need to head true north. But, because there are variations on the magnetic field on the earth, your compass will point to the magnetic north, located about eleven degrees from the tilt of. Since maps are oriented towards true north, youll find life much simpler if the n on your compass points to true north when you box your needle have the red arrow within the red outline the orienting arrow. The compass points to magnetic north, or about 17 degrees off true in central oregon the compass reading must be modified to true bearings so as to interface with the map. It is a good idea to be conservative and add 510% of the total distance to take into account things like switchbacks that dont appear on the map. Lay the compass on top of the map and align one long side of the baseplate along one of the magnetic north lines you added. Turn both map and compass together until the red end of the needle is on the n. Another method is to use a compass the mathematical kind set to a narrow distance on the map scale like. With our compass adjusted for local declination, were now ready to start orienting ourselves. In principle, the magnetic compass remains as simple as it was when it was invented in. In most locations on earth, magnetic north differs from true north, so magnetic declination has to be taken into account. The declination diagram is only representational, and true values of the angles of declination should be taken from the finding your way with map and compass u. At the midpoint of the western edge of this sheet true north is 01.
Orienting a map is the process to correctly align it relative to the local surrounds. In other words, an oriented may will have the top part of the map pointing true north, and the right side pointing east. What are the differences between true north, grid north, and. Introduction locating and maintaining boundaries is essential to easement monitoring knowledgeable use of a compass, survey, and maps is essential too use common sense and prepare properly so your visit is done safely 2. An area of zero declination runs up the center of north america. Using your compass relative to magnetic north using your compass relative to true north. Because of magnetic variation, which is the everchanging influence of the earths magnetic field, and magnetic deviation, which is. Additionally, your instructor will discuss declination magnetic north vs. North lines printed on your map are most likely aligned with either grid or true north. The amount of declination between magnetic north and true north varies across the world, so highquality maps always give the amount of declination. A magnetic compass needle will always point to magnetic north. However, the second thing to know when working with a compass is that magnetic north is not true north the north pole.
Holding your compass, rotate the dial until the n for north matches up with the index pointer. Online army study guide land navigation map reading. Be sure the north marker on the bezel is pointing north on the map, not south. Once you have done this, you are ready to take a bearing. Place the fully opened compass on the map with the scale edge alongside a north south meridian longitudinal line, grid line. If you point your compass towards true north, your compass needle is going to point a little to the east. Compasses are inherently magnetic instruments, and most commonly measure angles relative to magnetic north. In fact, most compasses point in the direction of magnetic north, a spot in the arctic that is near to but not the same as. The angle between tru e n o r th and magnetic north is called magnetic declination. Lacking trails, signs, or any other indicators, the student navigator is forced to rely on just 2 tools. Magnetic north is different to map grid north because magnetic north where the compass needle points changes in different places of the world and changes over time. The case cover should be pointing toward the top of the map. How to navigate by map and compass appalachian mountain club.
Now you can draw a line on the map along the straight edge of your compass. How to use a lensatic military compass navigate safely in. To use a compass with your map and your gps you need to have an understanding of the north reference used by each of them. Look at the index line to read the bearing youve just captured. The north magnetic pole is near, but not the same as, the earths true north pole. The procedure will work if the magnetic north south lines are drawn on the map. True north is a geographical direction represented on maps and globes by lines of longitude. North arrow of the lensatic compass will point 11 degrees west of true north. The first step of orienting with our map and compass is to make sure north on the map lines up with north in our terrain.
Make sure that the sighting wire of the compass is perfectly parallel to any north south lines on the map. In most practical cases, heading north is as simple as reading a compass and setting out. First, you need to determine your bearing the direction you need to travel. Put the map on a level surface such as the ground, and place the compass on top.
A compass needle will always point towards the magnetic north pole. Therefore, when using a map and compass together, an adjustment has to be made for declination. A topographic map does not show landscape in the same way a photograph or a painting does. Place the compass back on your map and readjust the map below the compass so that your longitudinal lines now point to true north. Rotate the map and compass together until the needle and the map both point directly.
Most likely your map and your compass are using different north references. Since maps are oriented towards true north, youll find life much simpler if the. The magnetic pole may appear to be either east or west of the. The longer your trip the greater the variance between the two.
Map of north america with latitude, longitude, and magnetic north. How to use a map and compass ordnance survey ireland. Here are examples of vary i n g declinations in mary l a n d. North references for navigating with map, compass and gps.
How to convert a magnetic compass course to true our pastimes. In fact, magnetic north is approximately 1,000 miles away from the true north pole, and the distance between these two points can. Youll line up your needle with the tape arrow instead of the arrow on your compass. To orient a map using a compass, first turn the compass dial so north is aligned with the direction of travel. Magnetic declination, or magnetic variation, is the angle on the horizontal plane between magnetic north the direction the north end of a magnetized compass needle points, corresponding to the direction of the earths magnetic field lines and true north the direction along a meridian towards the geographic north pole. Use the following procedure to obtain an exact travel direction towards your desired destination. This is a video summary of the article here on how to buy a compass. Since all maps are made on a true north bearing and the compass needle points to magnetic north, an.
To get to the north pole, or true north, just following your compass needle wont work. Making sure that the direction of travel arrow remains pointed in the general direction of the landmark 6a, rotate the entire baseplate until the orienting lines are running north south 6b and the north marker on the bezel is pointing to north on the map 6c. Unfold the compass entirely, so the sighting wire is level with the map. The magnetized needle of a compass usually does not point towards the geographical north pole, or true north. Magnetic declination, sometimes called magnetic variation, is the angle between magnetic north and true north. Each of these clues could be used to help the girls connect the reallife landscape around them to the twodimensional landscape on the map. During this course, students will also learn the components of a handheld compass, how to use and trust the compass, plus how to obtain and follow a bearing from map to compass and compass to map. Some navigators ignore the difference between grid north and true north due to their slight difference. Magnetic declination is the difference between true. All maps are laid out the same, with the north pole on top. Magnetic declination changes over time and with location.
Place your compass on any map near the declination diagram see the next page for an explanation of declination, with the edge of the baseplate along the true north tn arrow on the diagram. There are three different norths in common use and in some cases choices to be made about which to use on your compass, map and gps. Ordnance survey an ordnance survey maps tool that enables users to plot and record grid references, compass bearings, distances and magnetic declination or variation for single or multiple routes. Bryde 20 developing the true north route map as a navigational compass in a construction project management organisation. Mar 24, 2020 now, if you line the needle up with magnetic north, the top of your compass will be pointing towards true north. Now rotate the bezel until the orienting lines on the compass are aligned with the northsouth grid lines andor the left and right edges of your map. Developing the true north route map as a navigational compass.
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