Mountain Navigation Skills - Reminders
These notes are not a substitute for navigation training course(s) and regular navigation practice. Moreover all forms of mountain activity carry inherent risks. The author accepts no responsibility for any navigational difficulties and their consequences that users of these notes may incur.
Key features of mountain navigation
Navigators need to be aware of surface features, slope aspects, gradients, directions and distances. They need to be able to identify them both on the ground and on the map and to relate the two to each other.
- Ordnance Survey Explorer 1:25,000 and Landranger 1:50,000
- Harvey 1:25,000 and 1:40,000 (including BMC Mountain Maps).
Remember - maps record only the situation at the time of survey. They are also not error free.
Set (i.e. orientate) the map to the terrain so that your direction of travel is at the top of the map. Use your compass to do this if necessary. Identify on the map the terrain and features on the ground and vice versa. This ability is essential.
The closer the contours, the steeper the slope. Practice studying the map and relating the contour patterns to your surroundings. Learn to identify concave and convex slopes and to estimate gradients.
Preferably avoid routes on slopes steeper than 1 in 2, though up to 1 in 1.5 may be negotiable with care. Use the scale on your compass to calculate.
Prominent landform features, e.g. knolls, depressions, steep banks, may or may not show on the map, depending where contours happen to fall.
In fine weather in open hill country, practice navigating using contour interpretation skills alone.
Break your planned route down into shorter legs. Think about how you will reach the end of each leg, and whether it will need fine navigation. What features will you pass on each stage? On your walk, tick them off mentally as you pass them and note the time. Note potential escape routes.
There's less chance of going wrong if you go via an unmistakable feature to reach a less certain one. E.g. if you are looking for a path junction that may not be very evident on the ground, is there a clear feature that you can aim for, leaving only a short distance to navigate to the path junction?
Any linear feature may be used as a handrail, e.g. path, wall, fence, stream, crest of ridge, break of slope, valley, but use caution in poor visibility - check bearings regularly and time and/or pace distance.
Many handrails are also good catching features. If crossing pathless terrain to a crossing point (e.g. stile, bridge), or junction (e.g. a path or stream junction) on a linear feature, you will probably not arrive spot on and unless you can see it you won't know whether to turn right or left. Solution - use the linear feature as a collecting (or "catching") feature but "aim off" - that is, set a course sufficiently to one side of the point you are aiming for so that when you arrive at the linear feature you are confident which way to turn to use it as a handrail.
Particularly in poor visibility, confirm the handrail is the one anticipated by timing and/or pacing from your current position (fences, paths and tracks come and go, very small streams may not be shown on the map).
Catching features (also known as collecting features)
As well as the linear features already mentioned anything on the ground that you are unlikely to miss when you come to it can be used as a catching feature. For example if you are looking for a path off the side of a ridge and further down the ridge the map shows a sudden steepening of gradient, should you miss your path the steeper slope will serve as a catching feature.
An essential skill for route planning and in emergencies.
Naismith's Rule says:
- average walking speed is 3 miles or 5 kilometres an hour (12 minutes per kilometre) on the flat;
- add 30 minutes per 1,000 feet or 300 metres of ascent (10 metres of ascent per minute).
You are probably not average. Practice working out your own speed over a measured flat distance. Then practice on various gradients and terrains to decide what you need to add to arrive at a rule that works for you. Write the results down.
Better than timing over short distances (unless on steep and/or very rough ground). Where there are no well-defined line features, precise navigation in limited (or no) visibility requires accurate pacing on bearings from map feature to map feature, keeping distance between features short even if this means a lot of zig-zagging.
Test how many double paces you take to walk 100 metres on the level (for most people it is in the range 60 to 65). As for timing, the number will increase as gradient increases, so practice on slopes to learn what difference it makes. Write down the results.
Develop a reliable way of keeping track of the number of 100 metre legs you have travelled (e.g. transfer coins from one pocket to another).
OS GridThe UK is divided into squares with 100km sides, each with a unique 2 letter reference, e.g. SD (southern Lake District), NY (central and Northern Lake District). Grid squares on recommended maps have 1 km sides. A 4 figure grid reference identifies the SW corner of such a square and the grid numbers (eastings and northings) are shown on the map edges. A six figure grid reference identifies the SW corner of a 100m x 100m square. Eastings (the vertical lines) always come first. E.g. Ambleside is in 1km square NY 3704. Ambleside Church is in 100m square NY 374043.
A protractor compass with baseplate is essential. Look also for 1:25,000, 1:50,000 and mm scales for measuring distance and giving accurate grid references. For more accurate navigation look for a stable needle, a long baseplate and a magnifier for studying fine map detail, e.g.Silva Ranger 3 , Expedition 4.
Magnetic variation (also known as declination)
Magnetic north differs from grid north and also changes over time, so accurate transfer of bearings from map to ground or ground to map needs a correction. Currently in the Lake District magnetic north is about 3 degrees west of grid north. Remember "add for mag, get rid for grid".
Taking a bearing from the map and transferring it to the ground
- Place compass baseplate on map with side edge along desired line of travel and direction of travel arrow pointing towards destination.
- Keeping baseplate in position, rotate compass itself so its orientating lines are parallel with the north-south grid lines on the map, north end to map north.
- Remove from map if desired (though keeping it on the map sets themap).
- Adjust for (add) magnetic variation.
- Rotate whole compass so that orientating lines and needle are parallel, north ends to north.
- The Direction of Travel arrow now points along the bearing.
Taking a bearing on the ground and transferring it to the map
- Hold compass at waist height.
- Align orientating lines so that they are parallel with needle, north ends to north
- Point Direction of Travel arrow to the required feature.
- Adjust (subtract) for magnetic variation.
- When compass is placed on map, with baseplate side edge over your current position and orientating lines parallel with north-south grid lines, a line drawn along the compass edge would go through the feature. Following the same procedure from a different location would give 2 lines crossing on the feature, confirming its position on the map (triangulation).
If the feature has already been identified on the map, but your own position is unknown, when the compass edge is placed on the feature and orientating lines are parallel with north-south grid lines, a line drawn along the compass edge will go through your own position. Following the same procedure but sighting on a different identifiable feature will give you 2 lines that cross (approximately) at your position. NB for greater accuracy do this on 3 features, ideally each at roughly 120 degrees spacing. Where bearing lines cross on the map will be a small triangle. If you took the bearings reasonably accurately your own position will be in the triangle.
Following a bearing
Following a bearing accurately with nothing to sight on is well nigh impossible. And a 6 degree error means being 10 metres off bearing in every 100 walked. Instead, sight on an object on the required bearing, holding compass at waist height, and head towards object.
In poor visibility ask a party member to walk ahead and shout or signal to them to keep them on the bearing. Even better, have a line of 3 following the same bearing, the one bringing up the rear signalling if one gets out of line. If you are on your own in poor visibility, when you can sight on an object on your line of travel you can make use of it twice by checking the back bearing to it before you lose sight of it.
If you are forced off bearing to get round obstacles, check by how many degrees you have been forced off bearing and how far you have gone in the wrong direction before you can follow your original bearing again. Then correct as soon as practicable by walking that distance on a new bearing that deviates by the same amount but on the opposite side of your original line. If you are timing or pacing the leg, unless you are good at mental trigonometry you need to ensure that any deviation from your bearing is at right angles, regain your original bearing (now on a parallel course) when the way is clear, then make the deviation in reverse to regain your original course. You will have walked three sides of a rectangle but you do not add the time or paces spent on the two sides at right angles to your original bearing.
On level ground, practice following bearings round an imaginary equilateral triangle and see how near you can get to your starting point (the triangle test).
In complex terrain practice navigating to features you can't see from your starting point without using the map.
If it's not possible to follow a straight line, are there 2 distant objects on your bearing that you can keep in sight? If so, you can deviate from your line of travel in the knowledge that to get back onto it all you need to do is bring the two objects back into line.
Path navigation in poor visibility
Paths may diverge, become ill-defined or peter out. Many paths are not mapped and some mapped paths don't exist on the ground. So monitor progress and check you are still on the intended route by:
- Mentally ticking off changes in path direction, ups and downs, changes in gradient and any other identifiable features passed that can be located on the map
- Using timing and/or pacing in order to anticipate when you will arrive at the next identifiable point on the map
- Take bearings along the path and along any linear features passed or crossed and check that these correspond with the alignments on the map.
When navigating off-path in poor visibility the same principles apply, but as your path exists only in your mind's eye you cannot afford any lapse in concentration.
In poor visibility, even expert navigators get lost (minds aren't always focussed on navigation!). But an expert navigator knows how to relocate speedily. There is no best system for relocation - it depends on the particular circumstances, but always stop and determine an appropriate strategy. Pressing on hoping you'll recognise something risks both wasting time and making relocation more difficult. Think clearly about the seriousness of your predicament and adopt a well thought out strategy to overcome it.
Often your predicament will not be serious. If you are sensible, you will not have been walking for long without keeping in touch with the map. You will know the limits of where you can be and from the map you will be able to identify a safe direction to follow that will lead you to an obvious catching feature that you can use as an attack point or handrail to get back on course. But in a more serious situation several or even all of the following steps may be necessary.
- How long since you last knew your position? That will tell you your maximum distance from it.
- What direction did you think you were going? Does a back bearing in the direction you came suggest that to be the case? Is the terrain you passed through what you would expect from the map? If not in what directions from your last known point does the map show terrain that might fit? Did you pass any particularly distinctive features?
- If you are on or near a distinct line feature (e.g. path, stream, fence or wall, narrow ridge, well-defined break of slope) take a bearing along it. Which of such features on the map are aligned in that direction? Are there any changes in direction on the mapped features that you should be able to identify on the ground?
- If you are on a slope, which direction does it face (take the slope aspect bearing) and how steep is it? Is it concave or convex? Are there such slopes in your area of search?
- From the location options left, what would you expect to find by walking relatively short distances in particular directions, e.g. in terms of slope angles and direction, clear catching features (walls, streams etc), and other unmistakeable features. Pace fixed bearings so you can relate the various features you encounter to each other and get back to your original "lost position" if necessary. You can expand on this by pacing a "spiral" (really an expanding square) from your original position, with each circuit within the limits of visibility of the previous one; or by carrying out a sweep search (spreading the party out at right angles to the direction of travel whilst keeping each other within the limits of visibility). By the use of such techniques build up your own mental map (in complicated terrain preferably draw one) of the area you are in and try and identify it on your map.
- If after all this you still cannot identify your location, do all remaining possible locations have a common safe direction of travel (safety bearing) to clear collecting feature(s). If so, follow it rather than flounder about until exhausted - even if it means coming down the wrong side of the mountain and an expensive taxi ride.
Alternatively, carry a properly calibrated GPS and spare batteries. A GPS can quickly confirm your position on the map - provided it is set to OS GB map datum. And if it has a Trackback facility it can direct you back to your last known position. But a GPS is no substitute for navigational skill - especially if (when?) you realise you had forgotten to set it properly, the batteries have failed or it has suffered a malfunction!
The ability to navigate well in all conditions is acquired only through practice and experience. The ability to navigate well is also not a substitute for being sufficiently fit, well equipped, fed and hydrated for the intended activities or for paying heed to adverse weather warnings.
Some useful references
- Hillwalking - Steve Long/MLTUK
- Mountaincraft and Leadership - Eric Langmuir
- Mountain Navigation - P. Cliff
- Navigation for Walkers - Julian Tippett
© John Nash, revised March 2009