When planning a route, a key piece of information we must know is how long should the walk take us to complete. If we are not comfortable navigating at night, then we must plan to arrive at our destination before darkness. This is particularly important during the winter months. Being able to predict the duration of a walk allows us to decide how much food to bring and if the route can be completed in one day or should it be spread out over several days.
The formula we use is called Naismith’s Rule.
In its most basic form we decide what speed we are likely to walk at, usually 3, 4 or 5 Km per hour.
Measure the route on the map and convert to distance on the ground using the scale of the map. Eg. 20mm on a 1:50000 is 10 Km on the ground, 20mm on a 1:25000 is 500m on the ground.
Calculate how long it should take to walk. Eg. 1 Km at 3 Km per hour is 20 mins, at 5Km per hour it is 12 mins.
We then add 1 minute for every 10m we ascend. This can be calculated by counting contour lines. Eg. 1 km at 3 Km per hour = 20mins. Ascent 50m = 5mins. Added together it should take us 25 mins to walk the route.
For every 60 mins spent walking we can add 10 mins rest/ break.
Many people find a timing card usefull to carry as the calculations are already worked out.
Each student on one of my Mountain Skills Courses receives a fully waterproof timing card for quick reference.