Map compasswacbc

Map, Compass and Altimeter

Introduction to Land Navigation and Map/Terrain Following in the

Backcountry

Highlights on the Introduction to Land Navigation in the Backcountry

• Before the Quiz….• A compass works with or without a map• Maps and compasses may be feature rich or not• Good group dynamics supports good navigation• Low visibility navigation is an important basic skill• Stay found using start points and short segments orienting

your track and features frequently• We say bearing more often than azimuth: each refers to

direction

Base PlateLuminous Points*Ruler in Inches/mmMagnetic Needle with Red NorthOrienting LinesDirection of Travel Arrow*Declination ScaleOrienting Arrow with Red NorthLiquid Capsule or HousingDial with Incremental Graduations/Bezel RingUSGS Map ScaleSighting MirrorDeclination Adjustment ToolInclinometer Eight Principal Points

Lets start with a quiz.Can you match the parts of the compass with the image?

Compass Features

Lecture Topics• Basic land navigation tools and skills• Understanding the UTM grid• Adjusting for magnetic variation/declination• Use a compass as a protractor• Orient a map• Map and terrain following• Use a map and a compass to follow a route or route segment on a map

– staying found• Finding your location with a map and compass• Discuss low visibility and avoiding lost• Adding the altimeter to your navigation skill set• Resources for further learning

Types of Maps

• USGS 7.5 Minute Quads• GREEN TRAILS MAPS• Google Maps and Gmap4• National Geographic TOPO – digital• Garmin – digital and GPS display• Handrawn – Can be OK• DELORME Gazetteer• Others of course

Map Features, Colors and Legend

We generally use topographic maps in the backcountry and they can come in many different scales. Two popular scales are 1:24000 and 1:69500. One inch on a 1:24000 scale map equals a distance of 2,000 feet in the field. One inch on a 1:69500 scale map means a distance of 6,000 feet in the field.

Black. Indicates cultural (man-made) features such as buildings and roads, surveyed spot elevations, and all labels. Red-Brown. The colors red and brown are combined to identify cultural features, all relief features, non-surveyed spot elevations, and elevation, such as

contour lines on red-light readable maps.

Blue. Identifies hydrography or water features such as lakes, swamps, rivers, and drainage.

Green. Identifies vegetation of significance, such as woods, orchards, and vineyards.

Brown. Identifies all relief features and elevation, such as contours on older edition maps, and cultivated land on red-light readable maps. Contour lines show elevation above sea level. Index contours show numerical values on map.

Red. Classifies cultural features, such as populated areas, main roads, and boundaries, on older maps.

Purple. Shows updates over previous versions, but not yet confirmed.

Map Legend. Identifies production origin, scale, contour interval, grid and declination diagram and map name.

Maps are printed so that north is oriented to the top and Cardinal directions going clockwise.

Not all maps carry the same information

map not to scale

Maps: Published and UnpublishedPaper Digital/Online – USGS, GREENTRAILS MAPS

Greek topos, place, and graphien,To write or draw Let’s identify 10 different map symbols

Features and Features in Mountains

Here is a trick. 6-7 lines ofContour within one quarter inch on a1:24000 scale map will reveal about 26 to 30° angle of slope. My pinkynail is just about a quarter inch.

Divide the rise by the run, thenselect inverse tangent to get degreeof slope.

map not to scale

SADDLE

RIDGE

Map Features - Topography

HANDRAILSTREAM

DRAW

HANDRAILCLIFF/RIDGE

The Universal Transverse Mercator (UTM)Grid. Turning 3 dimensions into 2.USGS designated this standard in1974 for large scale map sheets like 7.5 and15 minute topos

10 6° zones in USA, w/2 in WA.60 6° zones worldwide. Number 1Is at the IDL 180°W Λ and 30 is at Greenwich, the Prime Meridian 0° Λ

Ask and look for the Principal Grid Coordinates – last 5 digits of the easting and northing.

We work with 1000m squaresto find or report a location, so a 4digit grid means an area inside 1000m,6 digits means an area inside 100m,and 8 digits means a point or areainside 10m

map not to scale

NorthingEasting

To determine grid value on a map point.Read UTM Grid lines right and up: Read east then northAlta Vista is 10 within meters of E9650 and N8265 onUSGS Map Mt. Rainier East Quadrangle (Washington) 7.5 Minute Series

Tick marks on the border of USGS Maps indicate UTM grid lines. UTMgrid lines are drawn on Green TrailsMaps. Map borders are in lat-long

Understanding Declination or the Variation between the norths

We are in a east declinationand the declination shiftsBetween Grid north and Magnetic North. The shift happens over time. An eastdeclination is a positive+ declination. 15.5° E is our grid vs. magneticdeclination variation for this class.

For this class we aren’t covering lat-long and True North in depth.

http://www.ngdc.noaa.gov/geomagmodels/struts/calcDeclination

More on Declination

• Use this link to find your declination for any point

• http://www.mappingsupport.com/p/gmap4.php?ll=41.310824,-102.041016&z=4&t=m

• mapingsupport.com pulls data from the NOAA NGDC for this calculation

• http://www.ngdc.noaa.gov/geomagmodels/struts/calcDeclination

Let’s Adjust our Compass

• We will adjust our compass to compensate for the variation between magnetic and grid north

• After adjustment our compass will point to grid north while the magnetic needle still points to magnetic north

• Diagram is east declination• Use the tool to adjust• Look for the ring or screw on back• Put Red in the Shed

How to Orient a Map• At your staring point, or any other point• But which direction?• You’ll know when you have oriented your map• To orient a map means to line up all the directions on your map with the same directions in

the terrain• Two methods: one with a compass and one without• Examine your surroundings for a prominent landmark that will be shown on your map and find

the landmark on the map. Now turn the map until the landmarks you recognize on the map match the landmarks you see.

• Orient a map by compass. Line your north arrow on the compass with your north pointing index on the compass. Lay your compass down on the map with the base plate pointing north along the map edge or grid line. Turn the map with the compass still lined up on it until the map and compass needle both point north.

• If you aren’t using a compass with adjustment for declination, or you haven’t adjusted your compass, line the base plate of your compass up along the magnetic north line on the declination diagram on the map.

• Let’s orient our map of the Prospect neighborhood with some features near by – next slide.

Orient a Map – Turn the map until the features you see along a line in front of you a matchup with the same line and the features on

the map – let’s experiment

ProspectTully’sSt. Joseph’sVios

Using the Compass to Plot a Bearing – Using the Compass as a Protractor

• Use the edge of the base plate of your compass to point your direction of travel arrow at a desired location on map – ignore the magnetic needle; for now!

• The first time you line your base plate with a southerly direction will seem very strange, but don’t worry!

• Draw a line on the map along the base plate to a desired location from a start or other point.

• Turn the compass housing until the orienting lines on the base of the capsule align with the north/south grid lines on your map. Your bearing in degrees is read at the Index Line or luminous north on the dial.

• Use north-south grid lines on map to help line up your compass orienting lines.

• Some compasses have a direction of travel line and arrow and some have a luminous point as a direction of travel point.

ANY POINT OR START POINT

ONE LEG OF YOUR ROUTE

Taking a Bearing with a Compass and Traveling Along a Bearing

• Identify a feature or destination you can see on your map.• Face that feature holding the compass out in front of you with the mirror open to about 60° looking at your feature over

the top of the mirror and the compass capsule at the same time.• Still aiming at your feature, turn the bezel ring until the red magnetic arrow lines up with the red orienting arrow Red is in

the Shed. • Read and record the bearing.• Take another, or more for precision then average the out.• If your compass doesn’t have a hinged cover/mirror be careful to ensure you are pointing your compass with the pointing

arrow.• Try to use more easily identifiable features.• Summits aren’t always needed – a distinct cliff band, a couloir, or other distinct feature can you a good feature to aim at.•

• Aim for a known point or landmark, take your bearing and head to it, and then onto your next route segment.• Taking new bearings as you travel.• Stop and check occasionally; are you tracking the same point?• Record your bearings and work together with your partners to check the work.• Be careful of metal and earbuds when taking and following bearings – interference causes errors.

The Back Bearing

• Determine a back bearing using degrees. Suppose you follow a 65-degree bearing from point A to point B and then want to go back to your original location. To do this, you use a back bearing. You simply add 180 to the first bearing. Your back bearing is 65 + 180 = 245 degrees.

• Or just look at the south luminous point on the compass to see the 180° addition.

Find Your Location by taking Bearings in the Field – Resection/Triangulation

• Make sure you have adjusted your compass correctly for declination in your travel area.

• Take a bearing to one landmark. Point the direction of travel arrow at it and turn the compass dial until RED is in the Shed and record your bearing .

• Place your compass on the map so that the orienting lines are parallel to the map's north-south grid lines.

• We are now using the compass as a protractor again.• Move your compass so the edge of its baseplate ends at the landmark, keeping it aligned

with the map's grid lines.• Draw a line along the edge of your compass from the landmark along the bearing you

took. You are somewhere on this line.• Repeat taking a bearing and drawing a line for a second landmark.• Where these two lines intersect is your approximate location.• If you are on a trail, along a stream you may only need to take one bearing as you line

may cross your location, but don’t give in to this technique if you have another good feature or landmark to take a bearing to.

What a Resection Looks Like

5° to Lundin 185° Back bearing

82° to Red262° Back bearingYou can see both peaks, but

are not sure where in CommonwealthBasin you are: but now you know

The Altimeter

• Watch versions• Standalone• GPS feature• Set/re-set your altimeter at start points and

known points !

Altimeter Navigation

• Contouring (travelling across a slope while maintaining constant altitude) is very difficult, particularly in poor visibility. The tendancy to walk slightly downhill in these situations can be removed by simply monitoring for any inidicated change in altitude.

• Upper and Lower limit alarms are useful for providing an indication that you have arrived at a predetermined altitude. This could perhaps be on the ascent to prevent over-ascending and suffering from altitude sickness or to locate camp or key navigational location or as a warning on the descent to avoid a cliff or crevasse noticed during the climb up.

• Combining map and traversing skills allows for direction finding on sloped ground. This technique is also useful for aiming at a target location althogh as with good compass use, it is usually better not to aim directly at your target but slightly away from it (aiming off) so that on arrival at a easier to identify nearby feature ( stream , wall, crag etc) it is a simple matter to turn toward the actual target rather than wonder whether you are slightly high or slightly low.

• The generally accepted wisdom of aiming-off with an altimeter is to aim low when ascending and aim high when descending which in both cases avoids overshooting the target and having to backtrack. Additional accuracy can be obtained using the altimeter in conjunction with a compass to locate a contour line along a given bearing and this does not require pacing regardless of how difficult the ground or conditions underfoot become.

• The compass can be used to take a bearing of the direction of the slope (known as the Aspect of the Slope) of the ground, this can then be transferred to the map. Now using the Altimeter to read the absolute altitude, where the nearest contour line crosses the Aspect of the Slope is your current location. This technique requires enough visibility to take an accurate reading of the Aspect and on shallow ground this is very hard to be accurate about but as with all navigational skills selecting the most appropriate method to use is a) down to having a wide range of options available and b) knowing how and when to use them.

Notes on Low Visibility Navigation• Did you have a plan with route segments – please say yes?• Use shorter segments and routes and keep track of your progress• Travel along hand-rails• Low visibility is not the time to split up• Send someone forward and line them up from the rear to follow

an bearing• Did you think about retreating before you had to?• Aim off a known point and handrail to it• You don’t have to wander into a cliff or terrain trap; how to avoid?• Many stories of escape and failure to escape in bad weather• Backcountry travelers need to keep this in mind

Further Resources and Learning• GPS• Google Earth, Google Maps, Gmap4• Turns All Year, NWHIKERS• USGS Topographic Map info • http://egsc.usgs.gov/isb/pubs/booklets/topo/topo.html• http://www.magnetic-declination.com/• Be expert with Map & Compass, Björn Kjellström• MAPS & COMPASSES: A Users Handbook, Percy W. Blandford

•

Learn to plan your trips and study maps from the grid to magnetic point of view,or the map to compass point of view. During your planning use your compass as aprotractor; forgetting about the needle. In Washington State we have an East orpositive declination. Plot a route on a map with a protractor then subtract the declination to follow the magnetic bearing. This is what East is Least means, and West is Best means add a West declination when plotting on a map. If you are takinga bearing with a compass in the field just reverse.

More on calculatingDeclination