Compass Basics Opening Comments Terms of a compass Boxing a needle Get a bearing (you to a point) Get a bearing (a point to you) Orienting a map Get a bearing on a map (from you to a point) Get a bearing on a map (from a point to you) Note: We will do practice exercises very slowly
Demonstrate effects of metal on compass Note: There are many ways to teach map and compass. For the purpose of this course, there is only one way (as given in your course handout). Every person in this course needs to learn Map & Compass. People have become separated from friends and loved ones in the wilderness. Everyone who goes out in the wilderness needs to have basic Map & Compass skills. Do not think that a GPS will save you in the wilderness. Good GPS skills and great mapping skill go together hand-in hand. Bring compass that the course provides !!! Do not jump ahead during the lecture – let me walk you through each slide! Opening Comments
Terms of a Compass Direction of Travel Bearing Index Point (white line under number) Base plate Dial Compass Needle Red end points Magnetic North Needle Box
Map & Compass Terms Bearing – The direction of a point relative to your position. Declination – The angular difference between True North and Magnetic North on the surface of the earth (once you orient your map, you dont have to worry about declination again). True North - Your map is based on True North (or Grid North). Envision a north axis (top) of the earth as it spins, or North Pole. See next slide. Magnetic North – The red end of your compass needle points to Magnetic North. See slide after next.
Super-imposed Grid Lines showing Grid North or True North Grid North here
Magnetic North - …determined that the average position of the North Magnetic Pole in 1994 was located on the Noice Peninsula, southwest Ellef Ringnes Island, at 78.3 degrees North, 104.0 minutes West. The yearly motion of the pole has increased, and is now 15 kilometers per year. Geological Survey of Canada True North grid line
Needle (red end) outside of box Boxing a needle (This displays a needle not boxed)
Needle (red end) boxed Boxing a Needle - (This displays a boxed needle) Big note – Sometimes you will box the needle by moving your feet, sometimes by moving the compass dial, and sometimes by moving the map. Your bearing is read here: 320° - (note the white line under the number)
Big Concept – How to box a needle !!! I will demo first, then the next slides will walk you thru it. A. Demo how to hold compass and view a distant object –Demo how to hold a compass at waist level and adjust dial to box compass (used when getting a bearing from you to a distant point). B. Demo how to hold a compass at waist level and box needle by moving feet (used when setting a bearing on a compass and determining a direction of travel). (give me a bearing (1° thru 360 °)
1 st Exercise – Find the bearing from you to a mountain peak in the distance. 1. Hold compass up and point Direction of Travel arrow at (area to be named): 2. Bring compass down to waist level. Make sure compass is level so that the needle floats freely. Box arrow by moving the dial: 3. Example of not boxed : 4. Read your bearing at the Bearing Index Point This is the Direction of Travel arrow. Note the small triangle on the tip – center this on the peak !!! Not boxed Move dial to box as shown Bearing Index Point (White line under N)
2 nd Exercise – someone tells you to follow a bearing of 90° or 270° from your current position. 1. Stand up. 2. Hold compass at waist level and keep compass level. 3. Move the dial on your compass until 90° (or E) appears at the Bearing Index Point. 4. Box the needle by moving your feet to the left or right. 1.Stand up. 2.Hold compass at waist level and keep compass level. 3.Move the dial to 270 ° (or W) at the Bearing Index Point 4.Box the needle by moving your feet to the left or right.
Step 1. Align Direction of Travel Arrow and Arrow Box on compass. Align Direction of Travel arrow and Arrow Box to be point in same direction by moving the compass dial. Orienting a map (Student Exercise)
Step 2. Align compass on side of map as shown (side is highlighted in green on your map). Note: Needle is not boxed at this time. Orienting a map cont.
Step 3. Grab corner of map and move left or right to box needle. Note: Needle is boxed. Orienting a Map cont. 1 st Big Visual Check – all 3 arrows are pointing in same direction
Step 4. Grab corner of map and move until magnetic needle of compass is about 13° to the right of the Arrow Box. The map is now oriented. 2 nd Big Visual check: the magnetic arrow should be to the right of the box arrow in the same manner as the diagram below Important Your Map is now oriented for declination
Obtain a bear from you to a peak (on a map) Orient your map as per previous exercise. Important – after you orient your map, do not move your map !!! We orient the map to adjust for magnetic declination. Features on the map are now oriented to you as they are on the ground. Do not pick up the map and walk around with it trying to find things. Follow next slides.
Obtain a bear from you to a peak (on a map) 1. Draw a line from your position to your Point of Interest # 1 on map 2. Align compass on line as shown with Direction of Travel arrow pointing at Point of Interest. Point of interest Direction Arrow always points towards Point of Interest Note: needle is not boxed yet You are here
Obtain a bear from you to a peak (on a map) cont. 4. Read your Bearing at your Bearing Index Point – the bearing is 290° from you to the peak. (a little inaccurate as pictured). 3. Rotate dial to box needle
Last concept - Obtain a bear from a peak to you (on a map) 1. Draw a line from your Point of Interest to your position. 2. Align compass on line as shown with Direction of Travel arrow pointing at your position 3. Rotate dial to box needle, as shown 4. Read your Bearing at your Bearing Index Point – the bearing is 110° from the peak to you. Bonus – Based on the reading from the previous slide, how can you determine the 2 nd bearing without putting the compass on the map?
Questions Question: If the bearing from you to a peak is 200°, what is the bearing from peak to you? Answer - 20°. If the bearing to the peak is greater than 180°, subtract 180. If the bearing is less than 180°, then add 180 to the bearing (Look at your compass to get a visualization) Question: What is the best way to find where you are on a map? Answer: Always know where you are at ! Track your movement on the map from the moment you park your car. Do not try to hike for a few hours and figure things out later.
Advanced Practice Trianglization - Locating yourself by sighting 3 points (without using a GPS). We will not demonstrate in this class (field exercise only). Orient your map on the ground. Must identify 3 good points of reference, widely separated. Next slide will demonstrate. Standing up and using the compass to sight on each of the reference points, determine bearing from you to each reference point/peak. Use straight edge and compass to draw a line from each peak/reference point using those bearings. Note: You must put the straight edge on the peak (with the Direction of travel arrow pointing at the peak) and box the arrow with the bearing you got for that peak/reference point. A triangle (as shown in next slide) will form where the 3 bearings intersect. You are located somewhere within that triangle. The more peaks that you sight and add, the smaller the triangle will become.