Map to Land Bearing

Map to Land Bearing


Use a map to land bearing when you need to check which way to walk, from a known point


Map to Land Bearing 

Map to Land Bearings



This type of bearing is the most common, as it allows the user to plan a course on which to travel by using the map and compass together, and is especially useful in times of poor visibility. Use this type of bearing when route planning too.


Key Steps for Map to Land Bearings

Stage 1 - calculate the bearing


  • known starting position (point A)
  • known destination position (point B)
  • place compass on map with base plate flat against the map
  • line up base plate with points A & B with direction of travel arrow pointing towards point B
  • turn compass housing/bezel so that orienting lines on base of compass housing line up with a vertical grid line on map, ensuring that that orienting arrow is pointing to the top of the map
  • once orienting lines aligned with vertical grid line, remove compass from map and note the degrees reading at index mark
  • allow for magnetic variation – do this by adding the appropriate value* to the value at index mark. You now have a magnetic bearing.
* the appropriate value depends on your location - see magnetic variation.


Stage 2 – using the bearing

  • hold the compass in the correct position and rotate your body so that the north (red) arrow is contained within the orientation arrow of the compass housing 
  • look ahead of you and draw a mental line in the direction of travel arrow of the compass
  • pick out anything that’s easily in view that you can walk towards. It could be a rock, a tree or anything distinguishable 
  • walk towards that object and repeat until you reach your destination

Note: if the weather is find & clear it may not be necessary to continually identify objects and walk towards them, for example where you have good visibility of 'point B'. Your reason for taking a bearing could be to check that the direction you suspect to be correct is actually correct.

Knowing when you get to your objective (point B) may take some further navigational techniques, such as pace counting, timing, feature tick lists, or a land to map bearing.

In poor visibility, or situations where there are insufficient land features to pick out to walk to, you may need to use a technique called leap-frogging, which is covered later in the navigation section.


Checking

  • at any point, you can check the accuracy of your bearing by turning around 180° and looking at the object that you’ve just left
  • hold the compass up as usual, but this time align the white (south) pointer within the orientating arrow
  • if you’ve walked accurately, the previous object should be in-line with the direction of travel arrow
  • if you’ve walked off-course, move yourself left or right to correct
  • turn 180°, line-up the red needle within the orienting arrow
  • continue walking as step 2


Common mistakes to avoid

  • always check on the map that it is actually safe to walk from point A to point B, and you’re not exposing yourself to a steep gully, or worse, in the process. See example below.
  • never try to walk on a bearing by holding the compass in front of you in the thought that you can keep the red needle inside the orienting arrow AND watch your footing at the same time. It’s easy to walk off course, particularly if there is a strong wind blowing from the side. Remember, even if you have the red needle aligned inside the orienting arrow, taking a few paces to one side will put you off course, but the arrow will still be pointing at the same bearing.
  • Stage 1 of the above process is only measuring the angle, or bearing, and the magnetic part of the compass is not required at that point. Don't think you've missed something and think you have to set the map to north too 
  • when selecting an object to walk towards, make sure it won’t move. In poor visibility it’s possible to mistake a sheep for a rock!
  • always get into the habit of taking account of magnetic variation


Example

In this example, the intended route is from Carn Ghluasaid to Creag a Chaorainn. Planning a direct line between those summits is fraught with danger as there are steep drops to the north and east. See figure 1 - the route shown by the edge of the compass is too dangerous to consider, as indicated by the contour lines being close together.


Figure 1


Figure 2


The only safe route is to take the journey between the summits in a series of shorter legs. Figure 2 shows the first of those legs.



Figure 3


Figure 4


Figure 3 shows the compass index mark against the bearing of 265°, which is the first leg of the journey as read from the map. However, as the bearing has been read from the map, it's a grid bearing and is converted to a magnetic bearing by adding the appropriate value for magnetic variation. In the case of north west Scotland in 2013 is approx 2°, leaving a bearing on which to walk of 267°.

Figure 4 shows the compass needle inside the orienting arrow, with bearing set to 267°.

Measure the distance to walk to the point where it is safe to change course towards the destination summit, walk & measure distance as you go, then repeat the process of taking a bearing from the map & walking on it, etc.

Videos

The following videos all demonstrate map to land bearings and are shown in order of preference and accuracy (inaccuracies are minor and noted).

Good rounded example of taking a bearing from a map and walking on it




This video is produced by Ordnance Survey and is good, but has one glaring omission. The user does not take account of magnetic variation



This is also a good video, produced by Silva - the compass maker - and introduces mirror/sighting compasses. However, no account is taken of magnetic variation




Practice Game

The next time you're out walking, take some sweets with you (jelly babies are a favourite). When you stop at a safe piece of ground, maybe for a lunch break, take a few minutes to practice pace counting. The game is simple:
  • two (or more) people start from the same point
  • decide on a direction in which to travel
  • take a compass bearing of that direction (just point compass direction of travel arrow to intended direction, then turn the bezl so that the red needle is inside the orienting arrow. There's no need to take account of magnetic variation as you are not using a map in this exercise)
  • walk on the exact bearing - taking care to pick an object in-line with the bearing, and walk to that object, rather than trying to walk directly on the bearing
  • count out how many paces (two steps) as you go, and when you get to a convenient point, stop and make a mental note of the distance travelled to get to that point. Remember, it's distance travelled, not paces that you need to remember
  • drop the sweets at that point
  • go back to the start point and tell your friend, a) the bearing on which to walk, b) the distance they have to walk
  • with any luck, you'll get a reward when you have travelled on the correct bearing for the correct distance


Links