Slide 1 - GrizzlyMan Adventure Race

3. Compass Anatomy Base plate Straight edge and ruler Direction of travel arrow Compass housing with 360 degree markings North label Index line Orienting arrow Magnetic needle (north end is red)

4. What is North? True North A line from any point on the earth's surface to the geographic North Pole. The direction of true north is marked in the skies by the north celestial pole (Polaris). Magnetic North The direction to the north magnetic pole, as indicated by the north-seeking needle of a magnetic compass. Grid North The north that is established by using the vertical grid lines on the map.

5. Declination At a given point on Earth, the angle between magnetic north (the direction the north end of a compass points) and true north. Declination is considered positive east (add to compass reading) of true north and negative when west (subtract from compass reading). Current declination for GMAR race area = 14� 8' E changing by 0� 9' W/year

7. Orienting the Map to True North Using Land Features Identify several landmarks on the map and on the terrain. Visually orient the map landmarks with the terrain landmarks. The map is oriented to True North. Using a Compass Identify the declination from your map. Since the declination in our case is East of true north you will subtract the declination (14� 8�) from 0 degrees (also 360 degrees). Rotate clockwise! Place the compass on the map so that one long edge of the base plate lies atop either the left or right margin. Rotate map and compass together as a unit until you have placed the needle in the orienteering arrow (or gate), so the north end of the needle points to the north mark on the compass housing. The map is now oriented to true north, every direction on the map corresponds to the same directions on the ground. It is also possible to orient the map to magnetic north, however we will not be covering that procedure in this presentation.It is also possible to orient the map to magnetic north, however we will not be covering that procedure in this presentation.

8. Orienting the Map to True North It is also possible to orient the map to magnetic north, however we will not be covering that procedure in this presentation.It is also possible to orient the map to magnetic north, however we will not be covering that procedure in this presentation.

9. What is a Bearing? A bearing is a horizontal angle measured clockwise from north (either magnetic north or true north) to some point (either a point on a map or a point in the real world). Bearings are used to accurately travel to a destination or to locate your position. Map Bearing � Working from your map, angle is measured clockwise from true north Magnetic Bearing � Working off a real point on the landscape with a compass, angle is measured clockwise from magnetic north Note that we are NOT using or talking about quadrant bearingsNote that we are NOT using or talking about quadrant bearings

10. Adjusting for Declination We will only be talking about adjusting for an EAST declination because this is what applies to Montana and more specifically the GMAR race area.We will only be talking about adjusting for an EAST declination because this is what applies to Montana and more specifically the GMAR race area.

11. Putting It All TogetherTaking a Bearing from the Map (Map Not Oriented) Note that we will only be discussing one map and compass case (taking a bearing from a map not oriented) as we believe this is the most straightforward method and most applicable to the GMAR.Note that we will only be discussing one map and compass case (taking a bearing from a map not oriented) as we believe this is the most straightforward method and most applicable to the GMAR.

12. Play Movie

13. Putting It All TogetherWalking a Bearing Taken from the Map After taking the bearing, as described above, hold the compass level and in front of you, so that the direction of travel arrow points to the destination. Rotate your whole body�until the magnetic needle lies directly over the orienting arrow. Make sure the north end of the magnetic needle points to N on the compass housing. The direction of travel arrow points to the destination. Site a prominent feature to which your direction of travel arrow points. Walk to that feature. Continue to sight on other features along the bearing and walk to them, until you reach your destination.

14. Putting It All TogetherTaking a Back Bearing To check your position while walking a bearing, you can take a back bearing. Before you start to walk on your bearing, turn around take a bearing 180 degrees off of the bearing you are going to walk. For example, if you are going to walk a bearing of 45 degrees, shoot a bearing directly opposite your course of 225 degrees. Locate some landmark along this bearing. Once you have moved a short distance along your bearing, turn around and shoot a bearing back to that landmark. If you are on course, that bearing will still read 180 degrees off your bearing of travel (in this case 225 degrees). If it doesn't, it means that you are off course. There are two basic formulas for calculating a back bearing.

15. Putting It All TogetherAiming Off & Baselines It is almost impossible to walk a perfect bearing. In most cases your error can be anywhere from 3-5� (known as lateral drift � see the figure below). Being off just a few degrees can make a major difference after several miles (see Table 6.1). Instead of heading straight for your target, it is best to deliberately aim to one side of your target (left or right). Then you will know whether to turn right or left and walk to the target.

16. Putting It All TogetherAiming Off & Baselines Baselines are helpful because they provide a large target to aim for. A baseline is a reference line that lies across your course. It can be a trail, cliff face, road, stream, or other feature. You can combine a baseline with aiming off to help navigate. Find a baseline near your destination, then aim off of it. When you hit the baseline, you now know which direction to turn to walk along the baseline to reach your destination.

18. Resources Randall, Glenn. 1998. The Outward Bound Map & Compass Handbooks. The Lyons Press. New York. Curtis, Rick. 1998. The Backpacker�s Field Manual. Three Rivers Press. New York. Kjellstr�m, Bj�rn. 2009. Be Expert with Map and Compass: The Complete Orienteering Handbok. Wiley.