Expeditions, Navigation, Guided Walks and Trekking
I have been playing with building a Walking Time table, using this when teaching Navigation. Here’s a copy of the table, if anybody wants a copy in a handy size to keep with your compass, drop me a note and I will post on when back from printers.
Anyway, after battling through some complex Excel formula and formatting, I came across a nifty website that will do the calculations, including Trantors corrections. These adjustments where new to me, and make sense.
Here are brief explanations;
Scottish climber W W Naismith put his rule together in 1892. It’s simple, effective and easy to remember on the mountain. In Imperial measures it uses an average walking peed of 3 miles per hour and an additional allowance of half an hour per 1,000 feet of ascent. Its much easier In metric, based on 4 km per hour and an additional minute per 10m gained.
For distances of around 10 km, it works well, as long as you have good conditions on good paths. To be more accurate the calculation needs to take into account the slowing effect of steep descents and the speeding up on gentle descents. Most times these offset each other, but when out trekking could be important.
If you have a big pack; have had a hard day or week; covering more difficult ground or weather, then it is necessary to make more adjustments. These are taken into account in Tranter’s corrections. They were designed to take fatigue and fitness into account, and consist of a table of adjustments for different fitness levels and different lengths of walk.
So, fitness level; time an ascent of 300m in 800m. If you are fit then the corrections reduce the time for shorter walks by up to half! Corrections then progressively increase the time estimates for both increasing walk lengths and reducing fitness levels. By adjusting fitness levels, Tranter’s corrections can also be used to take into account bad weather or the conditions underfoot. So if you have a big pack then drop down one fitness level. Similarly if the weather is bad and conditions under foot are poor, drop a further level. So a fit walker, with a big pack over rough ground should expect to take around twice (x1.83) times as long.