Basic Map and Compass Skills: How to Navigate in the Backcountry

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By Ken Stuber. Basic Map and Compass Skills: How to Navigate in the Backcountry. Fox Cities Backpackers Meetup. Note: I shamelessly stole most of the graphics in this presentation from various websites. I know that makes me a bad person Ive listed the various sites on the last slide . - PowerPoint PPT Presentation

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Basic Map and Compass Skills: How to navigate in the BackcountryBasic Map and Compass Skills:How to Navigate in the BackcountryFox Cities Backpackers MeetupNote: I shamelessly stole most of the graphics in this presentation from various websites.I know that makes me a bad person Ive listed the various sites on the last slide. Im a geek, not a graphic artist. I actually LIKE clip art .By Ken StuberMapsOnly useful for navigation if you know how to use one Several typesTrail Maps: tend to show trails, trail distances, intersections and main features, but does not show topography (at least not well, usually).USGS Maps: Designed for navigation, LOTS of information crammed into a small space. Can be difficult to read without practice.Specialty Maps: Often a hybrid of the above two types, such as the Trails Illustrated maps made by National Geographic. Great for trip planning and basic navigation.What to Look for When Choosing a MapWill you be travelling on-trail of off-trail?How heavily used are the trails you will be on?What is the terrain like?In general, youll need a more detailed map ifTrail is lightly traveledThere is little relief, terrain is monotonousYou will be off trail at allWhat scale? 7.5 min USGS maps 1:24,000. 1in = 2000ftCounty series USGS maps 1:100,000. 1in=1.6miContour LinesTwo dimensional representation of three dimensional spaceLines join points of equal elevationContour interval is the difference in elevation between linesEvery 5th contour line is an Index Contour which may have elevation marked on it.Reading Topography on a MapShaded Relief MapLooks like a stylized aerial viewShading gives depth, making it easy to tell mountain from valley.Reading Topography on a MapSummit Concentric circlesGentle Slope Contours spaced far apartSteep Slope Contours spaced close togetherRidge Arrows pointing down hillGulley Arrows pointing up hillStandard Topographical MapReading a USGS mapMap NameYear of Production and RevisionGeneral location in StateNext Adjacent Quadrangle MapMap ScaleDistance ScaleContour IntervalMagnetic DeclinationLatitude and LongitudeReading USGS Map Features and TerrainBlack - man-made features such as roads, buildings, etc.Blue - water, lakes, rivers, streams, etc.Brown - contour lines Green - areas with substantial vegetation (could be forest, scrub, etc.)White - areas with little or no vegetation; white is also used to depict permanent snowfields and glaciersRed - major highways; boundaries of public land areasPurple - features added to the map since the original survey. These features are based on aerial photographs but have not been checked on land.Reading USGS Map Features and TerrainReading USGS Map Features and TerrainUsing a CompassFamiliarize yourself with the types of compasses, their parts and featuresA quality compass will have a movable housing, scale and orienting lines, orienting and direction of travel arrows, and declination marks.Using a compass without a mapFind your intended direction of travel on the compass housingTurn the housing so that direction meets the Direction of Travel ArrowHold the compass in your hand in front of you, make sure it is perfectly horizontal and away from metal objects with direction of travel arrow pointing ahead of youRotate your body until the N-S arrow on the housing lines up with the magnetic needleThe direction of travel arrow now points in your intended directionUsing a compass with a map (step 1)Place the compass on the map so that the edge connects where you are with where you want to be.The direction arrow on the compass should point toward where you want to be.You can also use the scale on the compass at this time to measure distance (as the crow flies)Hold the compass firm on the mapTurn the housing until the North-South lines on the map are parallel with the orienting lines on the housingMake sure the N-S arrow on the housing is pointing toward North on the mapUsing a compass with a map (step 2)Using a compass with a map (step 3)Hold the compass in your hand in front of you, make sure it is perfectly horizontal and away from metal objects with direction of travel arrow pointing ahead of youRotate your body until the N-S arrow on the housing lines up with the magnetic needleThe direction of travel arrow now points in your intended directionTraveling on the taken bearingOnce you have your compass set for your intended direction of travel (taken a bearing), you need to get there.You can simply walk in the direction the arrow points, frequently checking the compassOr find a feature in the landscape (Unique tree? Rock? Ridge? Hill? Lake?) that lines up with your intended direction. Walk there and repeat.Correcting for Lateral DriftIts nearly impossible to walk a perfectly straight line. Your error doing so is called Lateral Drift.One technique is to deliberately aim left or right of your target, walk the expected distance, and then turn toward your target in the direction you intentionally missed. This way, you ALWAYS know which direction you missed it by.Navigating around obstaclesWhen you reach an obstacle, hike a rectangle around the object Set a new bearing 90 from your original heading and walk until you have cleared the obstacle. For example, if your original bearing was 315, hike a new bearing of 45. Count your paces to track distance traveled.Go back onto your original bearing, parallel to your original course until you clear the obstacle along that axis.Set a bearing 90 back to your original bearing (in this case 225) and walk the same number of paces.Now turn back to your original bearing. You will be along your original line of travel.How do you use a Mirror Compass?Allows you to see the compass dial and the background at the same timeHelps keep the compass level while taking a bearingCan be bulkier and weigh moreMagnetic DeclinationMaps are oriented toward true north.True North is the northern axis of the Earths rotation.Compasses orient themselves toward magnetic northMagnetic North is where the Earths magnetic field re-enters the earth, the northern pole of the Earths natural magnetism.Magnetic North changes slowly over time, currently: Latitude:N 8217'60"Longitude:W 11324'0"Magnetic Declination is the measure of the difference between true north and magnetic north, allowing us to correct for it when navigating.Magnetic vs True NorthMagnetic North changes over timeMagnetic North and True North are not in the same place, declination allows us to correct for it.So what does declination mean to us?Youll need to find current declination for where you will behttp://www.ngdc.noaa.gov/geomag-web/#declinationThen you need to adjust for it when taking a bearingYou can do this one of two ways:Buy a compass with a settable declination screwAdd or subtract the declination from the bearing you took on the mapManually adjusting for declinationRhymes and acronyms to help rememberCEEC: Correct Easterly Errors ClockwiseLARS: Left Add, Right SubtractEast is Least(-), West is Best(+)With East Declination, subtract declination from map bearing to get magnetic bearingWith West Declination, add declination from map bearing to get magnetic bearing.When going from magnetic bearing to map bearing, its the opposite!!Sites I stole graphics from:http://www.usgs.gov/http://www.exploringthenorth.com/porkiesum/map.htmlhttp://www.princeton.edu/~oa/manual/mapcompass.shtmlhttp://www.walkandramble.co.uk/expert-advice/how-to-read-a-map-and-compass.htmlhttp://www.enchantedlearning.com/geography/mapreading/topo/http://en.wikipedia.org/wiki/Contour_linehttp://www.spidercanyon.com/backiss/bimapnav4a.htmlhttp://blog.backpackerbucks.com/gear/10-little-goodies-worth-jamming-in-a-backpack/http://adventure.howstuffworks.com/outdoor-activities/hiking/how-to-read-a-topographic-map1.htmhttp://www.learn-orienteering.org/http://www.thecompassstore.com/http://academic.brooklyn.cuny.edu/geology/leveson/core/linksa/magnetic.html

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