plotting a bearing on your map

Plotting a bearing on your map

• You have just located the first point in an orienteering course. The clue indicates that the next location is 1.2km away on a bearing of 286° True. Your GPS indicates that you are currently at 586362m E 4113408m N.

• Use the Castle Rock Quad and follow along as we locate our next course point.

Castle RockQuad

You can use your compassas a protractor

Plotting a bearing on your map

• You have just located the second point in an orienteering course. The clue indicates that the next location is 1.9km away on a bearing of 138° True. Your GPS indicates that you are currently at 585220m E 4113710m N.

• Use the Castle Rock Quad and follow along as we locate our next course point.

Plotting a Magnetic Bearing

• Standing at a known road junction, we sight a bearing to a nearby mountain top. We get 234° Magnetic as our bearing.

• The local declination is 15°E so we add 15° to 234° to get 249° True.

Plotting a Magnetic Bearing

• We set our compass to 249°

• We line the north-south parallel lines in the bezel up with a north-south line on the map.

• We move the compass until the edge is on the road junction.

• We draw the bearing line onto the map.

Plotting a Magnetic Bearing

Getting a Bearing from the Map

• Place the edge of the compass along the desired line of travel.

• Rotate the bezel until it is lined up with true north.

• Read the true bearing

• Convert to magnetic by subtracting the 15° declination.

Compass Plotting Exercise

• Castle Rock USGS Quadrangle

• What is the true bearing from White Rock to the small pond just west of Zayante Road?

• What is the magnetic bearing?

• What water feature might you be looking at from White Rock at a bearing of 208° M?

Orienting your mapusing your compass

• Adjust the compass to look like the declination diagram.

• Set the compass down on the map with its edge parallel to a true north line.

• Rotate the map and compass until the magnetic needle is boxed.

• Don’t do this on a metal surface.