Just exploring an idea.

People wonder how long a route is going to take them. If you've never done a given route, how long to expect it to take?

I just calculate the percentage of the Naismith time for a range of routes I've run. That is, divide the mileage by 3, add the elevation divided by 2000 feet, and you get the time taken for a fast walker. Then divide the time you've taken on the route by the Naismith time. That gives you a rough idea of your Naismith factor.

So I, as a beginner fell runner who's only been running for 3 years, and in my very late 40s, reckon on under 40% of the Naismith time if I'm racing an AM or AL, and more like 45-50% of Naismith time for a pleasure run of around 26 miles +3300ft.

For example, I'm hoping to run the Ennerdale race this year, whose route's Naismith time is 11 hr 25. I've run a similar length route in 45% of Naismith time, so I'd expect to finish in around 5 hrs 15.

I wondered if anyone else has used this rule of thumb when calculating route times. And whether they notice a clear trend in the data. I've plotted a graph of my own Naismith factor for various routes against the Naismith time for each route. I can upload it if I can work out how...

I've found this pretty useful for forecasting times when I've gone out and done something for the first time - eg a Fairfield Horseshoe recce, or a couple of BGR stages. It's also a good objective measure of how I'm improving, giving a consistent measure to compare days out which have varied in length and elevation.

Of course, Naismith is the subject of many a long debate, the ground and conditions will vary, and this will never be scientific. But in my limited experience I find it sticks pretty well even for routes which vary in ratio of distance and elevation.

Do other people use a similar calculation? Interested in thoughts

Andrew.