Naismith’s Rule is used to give a rough guide for how long it will take to walk somewhere in the hills. The basics are that if you know how far you have to walk and the speed you’ll travel at, then you can work out how long it will take. Naismith’s also adds in the time it will take to walk up what are described as Easy Slopes. If you add these two times together, the distance and height gain, you’ll know how long it will take to get somewhere.
Naismiths original Rule is “an hour for every three miles on the map, with an additional hour for every 2,000 feet of ascent”. The modern version of that is 5km or approximately 3miles an hour plus 10 minutes for each 100m or 330ft rise. For shorter routes you can use 12 minutes per km and 1 minute for each 10m ascended.
But the question has to asked: Is Naismith's Rule accurate - No.
There are two main reasons for this lack of accuracy. The first reason is variability - this is because we’re all built differently - some people are taller/shorter, older/younger, faster/slower, etc. So you can’t assume that different people will walk over the same piece of ground at the same speed.
The second reason is not accurate is that it was never meant to be accurate. In 1892 Naismith called his idea a rule - this word has changed over the years and now we would call it a rule of thumb (which has absolutely nothing at all to do with beating your wife with a certain sized stick) Anyway, a rule of thumb is something which has been gained from experience and practice, rather than a calculation. So it’s sometimes correct but not always.
Also Naismith’s doesn’t take into account the type of terrain you’re walking over. Walking through deep snow, up a steep slope, changes in visibility, your fitness, the weight of your rucksack, etc. are just a few of the many things which will alter the time it takes to walk somewhere.
But one thing has to said, even though Naismith’s isn’t very accurate for most people, it is brilliant for one thing and this is that it’s very simple and it can be adjusted for your own situation in most locations and types of terrain. So instead of just guessing how long you’ll be walking for, Naismith’s provides a very simple way of roughly estimating the time you’ll be walking.
Over the years there have been many attempt to improve it - these are known as corrections.
Some of the corrections are obviously wrong - but don’t forget that Naismith’s is just a rule of thumb, which is basically just an estimate and so any changes to it will be equally inaccurate.
So let’s go over just a few of the corrections.
We’ll start with Tranter’s Correction - which (just my opinion) I think is based on a very wrong assumption. Tranter’s is based on how fit you are and the fact that people slow down at the end of the day as they get tired. It puts everyone into one of six numbered brackets 15, 20, 25, 30, 40 or 50. Using a calculation you can use those numbers to calculate your walking distance over a number of hours. The lower your bracket the slower you’ll walk.
The reason I think Tranters is wrong is that the bracket you’re put in to is based on how fast you walk 800m with an ascent of 300m. (my phone calculator tells me that’s a slope of 20.55 degrees - which is quite steep. But I would say that speed isn’t the same as stamina, which you need for a full day walking in the hills.
The Aitken correction changes the speed people walk on different terrain surfaces, as an example it lowers the walking speed from 5 to 4km per hour once you leave a path or track.
The Langmuir correction basically says that you speed up on easy downhill slopes - You still use Naismith’s but you deduct 10 minutes per 300m of descent for slopes between 5 and 12 degrees. It also says that you slow down on steeper uphill sections - so add 10 minutes to Naismith’s for each 300m descent for slopes greater than 12 degrees.
I would suggest that we all know how fit we are and if you’re a hill runner then 5km per hour for a whole day will be no problems. But for everyone else - I would suggest that you use Naismith’s as a minimum time to get somewhere.
So give it a try and see if it works for you. Don’t forget Naismith’s rule is 12 minutes per km and then add 10 minute for each 100m rise.
30 май 2024
