- Navigation aids
- Global Positioning System
- Navigation techniques
- Estimation of distance travelled
- Using back bearings
- Navigation in easy conditions
- Navigation in difficult conditions
There is little that undermines the confidence of a group more than feeling that they are probably lost. Nor is there much which undermines an outdoor leader's confidence more than not having a clue where you are. Capable and confident navigation is a major goal for most outdoor leaders. Without it, a leader's performance in the field and general reputation will never reach great heights.
Navigation and the leader
Bushwalking and ski-touring leaders must have a good knowledge of map reading and display a high standard of navigation. Good navigation requires observation, concentration and common sense, combined with practice and experience. Navigation is more than just finding your way - it involves awareness of the terrain, estimating how fast you are going, recognising features as you meet them, and being aware of where you are on the map at all times.
It is not always necessary for the leader to undertake all navigation tasks personally. By delegating the task of navigation to other members in the group, the leader has the freedom to move within the group and tend to other requirements. This, of course, doesn't mean putting away the map and compass; in fact quite the opposite. It means being able to delegate the front position but still maintain a sufficiently watchful eye on map and compass to ensure that the navigational requirements of the party are met.
To become proficient in navigation, practice in the field is essential, along with familiarity with all of the following:
- the types of maps available and who produces them
- the various scales and their use
- signs and abbreviations generally used on maps
- methods of showing height or altitude (e.g. contours and their interpretation)
- the relationship between grid north, true north and magnetic north
- setting or orienting a map
- from visible features
- by compass
- the six figure grid reference system
- the use of a baseplate-style compass to follow a bearing in good and poor visibility
- plotting a compass course from the ground and from the map
- methods of obtaining resections or back bearings with the baseplate compass
- navigation across country with a map, but no compass
- natural direction finding (e.g. use of sun, moon or stars)
- preparation and use of route-plan cards
- methods of teaching simple map and compass work to beginners.
In summary, you as leader need to be able to quickly build up a mental picture of the shape of the country from the map. You must appreciate the interacting effects of vegetation cover, weather conditions, travel speeds, party fitness and other problems of travel on foot and ski.
Use of a compass supplements navigation from maps, and is best undertaken when required, and not constantly. The degree of error when using a compass in open country is typically about 3–4° and more in scrubby, rocky or thick country. The following precautions should be observed when using compasses:
- Do not use a compass near iron or steel objects. These include steel torch cases, knives, watch bands, tools, steel-framed spectacles, belt buckles, steel pack frames, etc.
- Local deposits of mineral ores may also affect a compass, e.g. over large areas of Western Australia, South Australia’s iron-ore deposits, and sections of the Bogong High Plains in Victoria. If the compass bearing alters significantly from when it is held near the ground to when it is held high, local magnetic effects should be suspected. In this situation, try to move to a location without such effects. If the effect is widespread, one suggestion is to note the bearing on the ground, and the variation at waist height. An additional half of this difference should then be applied to the bearing at waist height.
- Do not use a compass near exposure meters, cameras with built-in meters, or other electronic gear.
- Do not use a compass in close proximity to electric power lines or motor cars.
- The filament of some torch globes, acting as an electromagnet, may deflect a compass needle or affect its polarity if the torch is on.
- Most compasses manufactured for use in the northern hemisphere will not operate satisfactorily in the southern hemisphere and vice versa. This is because the needle is weighted for magnetic dip, which is different in the two hemispheres.
To obtain the best service from any type of magnetic compass, it is advisable not to store compasses together in steel cabinets or drawers. Over time some of them may have reversed their poles. Liquid-filled compasses, including most commonly used brands, may develop a bubble in the liquid after a time. The bubble will increase in size with an increase in altitude and changes in temperature, but it does not affect the use of the compass unless it becomes quite large. The needle case can generally be replaced by the manufacturer or their agents.
The altimeter gives a reasonably accurate estimation of altitude. With the introduction of the wrist or watch altimeter, altimeters are becoming more frequently used in outdoor recreation. For example, when walking up a spur to the summit, you can check your position on the spur by matching the altitude given by the altimeter to the contours shown on the map.
Altimeters have certain limitations which can easily mean that the information they give you is misleading. An altimeter is a barometer which measures the atmospheric pressure and compares it to a known pressure—sea level. As the air pressure is constantly changing, even at sea level, the altimeter needs to be adjusted to the known altitude every now and then so that it has an accurate reference point. Depending on the weather this can be necessary several times a day. If the weather is stable, an adjustment will be required less frequently. It is good practice for the navigator to recalibrate the altimeter whenever a known altitude is reached to ensure greater accuracy.
Global Positioning System (GPS)
The Global Positioning System (GPS) fixes its position on the ground by referring to satellites which orbit the earth. As GPS units are continuing to reduce in both price and size, more people are venturing into the world of navigation in the bush with this handy tool. However, before you take a GPS on a trip it is important to understand a few basic features about their operation, which are given in Chapter 31. It is strongly suggested that a GPS be regarded as another tool in your repertoire of skills, rather than a tool to replace other skills, knowledge and ability in navigation and route finding.
There are a number of specific navigation techniques which hcan be very useful in certain circumstances.
Aiming off (intentional error)
Aiming off is a technique used to find an objective on a definite, continuous line, such as a river, mountain ridge, coastline, road, etc. The navigator deliberately sets a course which is calculated to strike the line some distance to the right or left of the objective. Thus when the line is reached, there is no doubt as to which way to turn to reach the objective. For example, if aiming off to the right, you know you must turn left.
The amount of aiming off will depend on a number of factors, but as a guide for average conditions and distances, 10° could be added to or subtracted from the bearing. The longer the distance over which aiming off will be carried out, the smaller the aiming difference can be.
An attack point is a feature which is near your objective, but much easier to find. For example, if you were wanting to reach a hut in a forest, you might identify a definite creek junction or nearby prominent knoll. You would navigate to the junction or knoll, and once there the hut will be much closer and hence easier to find, say by compass bearing.
Catching features are prominent features which are beyond your objective. For example, you may be aiming for a track junction which is in front of a particular peak, stream or road. If you reach the catching feature, although you have gone too far, you have limited your overshoot. Obvious catching features will not always be present, but they can be manufactured, e.g. the bearing on some prominent nearby peak.
Navigators should always be on the lookout for handrails, which are definite linear features such as tracks, sharp-topped spurs or ridges, fencelines etc., which are roughly aligned with your intended course. If the handrail is offset to one side and not exactly in the right direction it still may be worth detouring for, especially if it makes the going easier. Creeks or gullies as handrails must be assessed on their individual merits, as often they are not easy going. It may be possible, however, to travel parallel to them, just out of the denser scrub or just off the steepest ground.
It is usually desirable to dodge around obstacles and make best use of open routes through scrub and timber and then reposition yourself on your original course within a short distance. One way to do this is to identify a distinctive feature on course a few hundred metres ahead and then walk to it by the easiest route. The same procedure applies for travelling in flat, featureless country. If a large deviation is required and there is no obvious distinctive feature to aim for, you may need to use your compass and pace count around the obstacle.
Estimation of distance travelled
This is one of the hardest things for a navigator to do, yet it is one of the most important. In many situations it will be a major guide as to where you are. For example, if you are following a ridge or track and have to pick a particular side spur or side track when they all look similar, you will have to work out how far you have come. To estimate the distance you have travelled requires:
- regular checks of the time
- experience in estimating your actual speed in kilometres per hour
- ability to calculate distances from your map
- simple mental arithmetic or use of rules of thumb for typical group speeds in different conditions.
For example, if you knew you had been walking for half an hour since leaving the last definite feature, and you estimated your speed during this time at 4 km/h, then you should be about 2 km away from that feature.
The elapsed time interval may be used in two ways to estimate distance. The first, and most useful for forward planning requires scaling from your map the distance to your next objective, calculating the approximate time required to reach it, and hence predicting your time of arrival. If you arrive at the objective too soon or too late, it is probably not the right one. The second approach requires noting the time taken to get from the last known feature to where you are now. From that you can estimate your distance from the last known feature which assists in locating yourself on the map.
Pace counting to determine distance travelled, while widely used in orienteering and rogaining, is seldom used in bushwalking except perhaps for short distances in conditions of very poor visibility.
Accuracy with estimating speed only comes with experience, although some guidelines are given under route planning in Chapter 3. For those who are not a whiz at mental arithmetic, it may be helpful to carry a copy of the chart shown in Figure 3.1 in your map case. It can be used to determine one of distance, time or speed, given the other two, simply by laying any straight edge (such as the edge of your map) across it.
Using back bearings
If you are not sure where you are, you can calculate your position on the map by using known points of reference. For example, if you are walking along a lengthy featureless ridge but are not sure how far you have walked, you can use any identifiable features to either side or ahead of the ridge which are also on your map to help you find your exact position on that ridge. Likewise if you are uncertain where you are on the map, yet you can identify two, or preferably three features that are also on the map, you can calculate your position by resection or triangulation.
To perform a resection or triangulation:
- Identify a feature which is shown on the map you have.
- Take magnetic bearings from your position to that feature.
- Convert that bearing to a back bearing (i.e. either add or subtract 180°).
- Convert the magnetic back bearing to a grid bearing.
- Now plot that bearing on the map by drawing a line from the known feature you have selected in the direction of the bearing you have calculated.
- Repeat this procedure with two other known features on the map.
In theory the result will be a point where the three lines intersect. In practice the result is often a small triangle where the three lines meet. Your position lies somewhere within that triangle. Using back bearings to perform a resection or a triangulation always takes some time, even when you are proficient. It is worthwhile practising before you really need to use these techniques!
Procedure when lost
This is discussed in Chapter 38.
Navigation in easy conditions
In open country when the weather is clear, navigation is generally done by direct map reading and identifying landmarks rather than by constant compass bearings. Good navigators refer to their compasses only occasionally under such conditions.
As navigator you must be able to form, from the map, a mental picture of the country to be traversed, before you actually cover it on the ground. This is rather like a musician examining printed music—a skilled musician will know what the music will sound like without having to play it. Similarly, a good navigator will know what the country will be like from examining the map carefully.
As a prerequisite you must therefore know what common natural features look like as patterns of contour lines. Common features include knolls, saddles, implied knolls or necks, gullies, cliffs, plateaux, ridges, spurs, stepped spurs, creek junctions and so on. Identify as many features as you can. As you proceed, the country should unfold more or less as you have visualised it. It is normal to keep the map handy and check progress or refresh your memory every 10 or 15 minutes. This helps to correct errors before they become large and start compounding. If a change of direction is intended at a particular point, for example, a track junction, note how that feature is situated, such as in a deep saddle or on a slope facing gently down in a particular direction. If the first track junction encountered is not in this situation then the map should be checked closely. The track junction is probably not the desired one, but may be a new one or a minor one ignored by the map makers, with the correct junction further on.
An additional check in hilly country is to always note from the map whether you should be ascending or descending. When descending a spur or when following a creek upstream, take care to observe all junctions. To assist in identifying the location of a branch spur, practice estimating the amount of height you have lost. Some navigators carry an altimeter for this purpose. Navigationally it is much easier to ascend a spur, or to follow a creek downstream, as the correct way at each junction is obvious.
In parts of hills or mountains where prominent features are few, it is useful to think in terms of watersheds or drainage basins, which are separated from one another by ridges or major spurs. If your route crosses several watersheds, you should always be aware which one you are in and the general direction the creeks should be running.
Should the country being traversed not match the mental impression formed from the map, then stop and carefully check the map and the route taken. First, align the map with north, so that it is the same way around as the country you are in. Look at the terrain, try to imagine what a map of it would look like and then attempt to find a matching piece of map. It may help to consider whether you have under- or overestimated your speed, strayed off your intended course or possibly overshot your objective.
If you cannot locate yourself on the map, take back bearings from definite features around you, conduct a resection, or retrace your steps until you can definitely locate yourself again. You could decide to walk for a definite time in a definite direction in an attempt to strike a recognisable feature - but only do this if there is a high likelihood of finding a definite feature within a relatively short distance.
It is useful to call a rest break to give you some time to examine all information from the map and the surrounding features without arousing too much interest from the rest of the group. Try to resolve the situation as quickly as possible, before ‘geographical embarrassment’ turns into ‘lost’. Procedures to use when lost are discussed in Chapter 38.
Develop the habit of looking back and memorising landmarks as seen from the opposite direction. For example, when ascending a peak and intending to return by the same route, take particular note of any critical points where it would be possible to go astray on the descent. Even if you do not intend to retrace your steps, this may be forced upon you by a variety of unforeseen circumstances, e.g. lost persons, lost equipment, lost route, change of weather or injury.
Navigation in difficult conditions
Conditions such as poor visibility, foul weather, thick scrub, logs, cliffs and steep or uneven slopes make it very difficult to maintain exact bearings and to judge distances travelled. The competent leader must have the ability to navigate in these conditions, despite fatigue or physical discomfort, with obvious confidence and with a minimum of conscious effort. If navigation is difficult, you could nominate a temporary party manager to look after the group for as long as you need to concentrate on the navigation.
Poor visibility may be caused by fog, heavy rain, whiteout, thick scrub or darkness. This may be forced upon the group by a sudden change in weather or may be due to a deliberate decision taken by the leader. For example, the leader may have purposely included night navigation (perhaps to arrive on the summit of a nearby mountain for sunrise), or has assessed the party as having sufficient experience to continue in the dark. Travelling at night increases the difficulty of navigation and the risk of injury to party members. The leader should consider carefully whether travelling at night is worth the added risk.
Under conditions of poor or zero visibility, do not rely on a sense of direction. Even when following a well-defined feature, consult your compass frequently and heed it. It is advisable to stick to well-defined features as much as possible, e.g. tracks, sharp ridges and spurs. When this is not possible, compass traverses must be resorted to, but these should be kept as short as possible and used to proceed from one well defined point to another. Make full use of the navigational techniques such as catching features, attack points, aiming off, handrails and methods of negotiating obstacles. If each stage of the compass traverse is short and terminates at a well-defined point, then any straying off course can be corrected without difficulty.
In poor visibility (e.g. less than 100 m) on a flat featureless area, the party should travel in single file with the navigator three or four places from the front. Appropriate corrections to the compass line of march can be called, using the front person as the aiming point.
When following snowpoles when the next pole cannot be seen, the ‘long cord’ method should be adopted. This involves sending one person out with the end of a cord which is long enough to reach the next snowpole (usually 40 m). The person moves in an arc until the pole is found, then the remainder of the party follow (Gatty 1977).
To determine distance travelled under conditions of poor to zero visibility, pace counting may be useful. A pace means a double step, i.e. you count each time you put your right (or your left) foot down. For a person of around 1.8 m height carrying a pack on level ground, pace length would be about 1.5 m, which makes about 660 paces to a kilometre. It would be very unusual to pace count for longer distances than this. People shorter than 1.8 m will tend to have shorter paces, and taller people longer ones. Navigation in difficult conditions requires practice, which is really only gained by going out there when the conditions are difficult.
Use all the information
Many, if not most, mistakes in navigation are made because only one or two variables are used to check position. A map usually contains a wealth of information, much of which may not appear relevant to your immediate location. This information can be used to your advantage for confirming the accuracy of decisions based upon only one or two variables. Two creek junctions may appear to be quite similar but they can usually be identified by checking the detail of the ridges and spurs surrounding them, or by the distance or direction from some other feature.
For handy reference, copy Table 11.1, and attach it to your map case. Considering all these factors should give the same position. If not, reassess your position and direction of travel very carefully.
Table 11.1 Navigation: Consider all of these factors
|Direction of travel, including recent changes of direction|
|Distance, based on elapsed time and direct estimation|
|Terrain features encountered, e.g. number of creeks, hills, etc|
|Slope of land about you - direction and steepness|
|Direction of features, e.g. creeks, gullies, roads|
|Bearings of prominent visible features|
|Relative height or shape of visible features|
There are a few warning signs which all leaders and navigators should be wary of. Perhaps the most commonly heard is ‘The map must be wrong!’. If you hear yourself, or someone else in your group say this then be very careful. Maps are sometimes wrong but people using them are wrong much more often!
A number of useful books specifically related to map reading and navigation are mentioned below and in the reading list (Appendix 3).
1988. Map Reading Guide. Central Mapping Authority of New South Wales, Bathurst, NSW, Australia.
1997. Map Reading Hand Book, 3rd Edition. Land Information Services, Department of Environment & Land Management, Hobart, Tasmania.
Gatty H. 1977. Nature is Your Guide. Fontana, Sydney, NSW, Australia.
Phillips R, Phillips N & Foley G, 1989. Cross Country Navigation. Outdoor Recreation in Australia, Perth, WA, Australia.