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More in this series:
Below is the answer sheet to the questions in the last part:
Part 3 of my Navigation Techniques series will look at Timing and how we can use it to measure distances and plan routes in the hills and mountains.
Timing
As mentioned in my previous article, we can use time to measure distance. In school, you may have learnt the equation: Speed = Distance/Time.
If we know how far away something is, and we know how fast we are walking, we can work out how long it is going to take to get there. The average walker's pace is roughly 4km per hour. This means an average walker can cover 1km in 15 minutes or 100m in one and a half minutes.
However, our walking speed changes depending on terrain, fitness and conditions. Walking up hill generally slows our pace. Boulder fields, scree and boggy ground will also reduce our speed. Even walking in to a head wind and carrying a heavy rucksack affect how quickly we can walk.
Getting accurate at timing is a case of trial and error. Especially on variable terrain and going up hill.
Practice measuring a distance on a map and then walk between the two points you have measured and time how long it takes you. Do the same over and over again, but on variable terrain, going up hill and/or wearing a heavy rucksack.
Another option is to use a standard sized football pitch and pace your 100m. Time how long it takes and practice walking the same 100m at different speeds. Multiply this 100m time by 10 to get how long it will take you to walk 1km.
Get a feel for different walking speeds and over time, with practice, you will develop a natural sense of how fast you are walking and you can plan a route accordingly.
Every time I start a walk in the hills and mountains, I make a note of the distance of my first leg and time it. This gives me a good indication of my walking speed and I can re-calculate my timings accordingly.
Take a look at the example of a timing card below. These take away the need to do maths! We use them from the initial planning stage at home, to using them out on the hill to work out small legs.
Using the card above, we can work out that walking at 3kph and that we want to cover a distance of 5km, it will take us 100 minutes or 1 hour and 40 minutes.
Timing is also a useful way to measure distance on the ground whilst walking. In conjunction with pacing, we can work out the distance on the map and then, based on our walking speed, time that leg. We can use a stop watch and check it regularly or set a timer with an alarm function.
Timing is best used over longer distances, over 400m for example, so long as you keep a regular pace. Counting paces over large distances can become inaccurate and boring!
When timing, it is important to stop the clock if you stop! And that means EVERY TIME you stop on that timed leg. Otherwise your timings will be inaccurate.
Timing is often used as a rough estimation but with practice, you can become more and more accurate. Practice pacing AND timing together to get the feel of how they both relate with each other.
Even without actually timing a leg, you can use rough times to help find your position on the map. See the example below:
I left the marked stream on the miners track, traveling south west, about 15 minutes ago and I am walking at 3kph. Roughly where is my position on the map?
Using the timing card above we can see that in 15 minutes, walking at 3kmh, I can travel 750m. Using this information, we can measure 750m along the footpath South of the stream and find out roughly where we are:
When doing this, we need to ensure we know how fast we are walking to get an accurate location. It is generally best to under-estimate our walking speed and accept a tolerance of 10%. With the example above, we can expect to be any where from 650m to 850m away from the stream.
Naismith's Rule
As a general rule of thumb, we use a rule called Naismith's rule to calculate time taken when walking up hill. This rule takes into account the time taken to climb 10m in ascent, or one contour line on OS maps and some Harvey Maps.
At a basic level, and the one we will adopt here, we add 1 minute for every 10 metres in height gained. On maps with 10m contour intervals, we can do this by adding up all the contour lines we cross on our route going up hill. See the example below:
The distance from the marked point on the map to the Trig Point on Cosdon Beacon is roughly 1.6km in a straight line. Walking at 4kmh it would take 24 minutes. However, if we use Naismith's Rule and add one minute for every 10 metres in height gained, we would have to add 16 minutes to our time as we cross 16 contour lines and climb 160m, making a total time of 40 minutes.
Looking at it from a different angle, we start at 390m and climb to 550m. We can work out the height gained from these two points and convert this into Naismith's rule.
Below is the question sheet to this article. Before you can answer the questions, you will need to download the following resources:
You will need to print these out but ENSURE you print them ACTUAL SIZE and not FIT/FILL TO PAGE. Take a look at and check your printer settings before printing and then check the measurements with a ruler using the table in the PDF. You will need to cut out the distance card. You can then laminate it for use on the hills and mountains!
Question Sheet:
To put these skills into practice and to learn more, take a look at my Navigation Course I offer.
All confirmed bookings will receive a 10% discount code to use on Harvey Maps products from their site.
Next Up:
The next article in this series will be Part 2.4: Bearings
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See you At The Edge!