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Navigational Skills 5 All you wanted to know about Naismith's Rule and Route Timing

Tranter’s Corrections?

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by Dave Roberts on September 24, 2014
Skills and Tips

Tranter’s corrections are often quoted, but seem to be based on a strange premise of what constitutes fitness. The table below then corrects your Naismith Time depending on your level of ‘fitness’. It also goes as far as saying that this walk’s too much for you slow coach. All well and good, but my fully opinionated opinion is below. Feel free to add your comments below if you disagree!

The problem that I have with Tranter’s Correction is that it bases your fitness specifically on the speed you can cover 800m with an ascent of 300m. So basically, if you’re fast then you have more stamina.  I am just unable to see what premise that’s built on. To me it’s a bit like saying that as Bolt can cover 100m faster than Farrah, ergo will beat him over 10km. Just nonsense. You may easily complete the challenge in 15 minutes, but struggle at anything after 4 or 5 hours, or someone else might take 30 mins to complete the ascent, but is one of those ‘steady eddies’ you see on the mountains. They just keep on going, steady, plodding ever onward, never stopping.

I’ve completed some trail/fell runs somewhere around the highest level, which is strictly running territory but there’s no way I could continue that pace any longer than I could walk and certainly does not bestow the stamina on me to continue on to 24 hours!

If you ignore the ‘fitness’ aspect of it, then Tranter’s Corrections offer a useful sliding scale instead. If you know you can complete a longish walk somewhere at the 20 min fitness level, and you’re going to attempt it in snow or over the Rhinogydd (or both!) then you can slide it to the next level. But then, you may as well be adding an hour or two to your Naismith Times.

I’ve never found cause to use Tranters at any point, and the fact that it isn’t even mentioned in the current handbook for the ML course speaks volumes. Do any of you actually find it useful? I’d be fascinated to see if anyone uses this rule regularly during their planning,

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Dave Roberts
Dave Roberts founded Walk Eryri in 2004, with the aim of providing routes that are off the beaten track. Walk Eryri is now part of Mud and Routes which continues to provide more off beat routes and walks in Snowdonia and beyond. Dave has been exploring the hills of Eryri for nearly thirty years, and is a qualified Mountain Leader.
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  • Bob
    August 14, 2015 at 9:01 pm

    Coming to this a bit late but you are featured in Wikipedia and still near the top of Google for “Tranter” – respect! I agree there is a lot wrong with Tranter – firstly, where are you going to find a Tranter hill (800m along and 300m up)? Secondly, your question of stamina versus sprinting. Finally, it doesn’t make sense that the Naismith hour between 8 and 9 takes 1.25 hours for a “very fit” while the two Naismith hours between 22 and 24 take an hour each. There are 8 places in that table where the incremental time is less than the previous incremental time – i.e. speeding up.

    There is a useful if obvious idea there, though, which is that you get slower as you get tired. None of the other methods recognise that fact. On a recent Ennerdale horseshoe walk, I had pre-estimated times with Naismith and Langmuir, and we made a note of a dozen checkpoint times as we went. So I did a bit of linear regression and fiddling and came up with: 12 min/km = 5 km/h on the ground (same as Naismith) plus 3 sec/m = 5 min / 100m climb (half of Naismith) plus an extra 0.5 min/km and an extra 0.5 sec/m for every hour we had been walking. So e.g. after 6 hours walking, we would estimate 12+6×0.5 = 15 min/km and 3+6×0.5 = 6 sec/m at that point.

    That matches all our times very well – a pair of fit (but not fell-running fit) 55 year-olds, on mostly good paths in great weather. Our total walking time was 11:08 compared to an estimate of 11:17 (based on 35km, 2200m). Of course it will be different for different people and conditions, but I guess the half+half part of the rule might be quite reliable. What do you think?

    (Regarding Langmuir – the time taken to add up gentle and steep descents on the map massively exceeded the difference of 5 minutes it made to the overall estimate. Not going to bother with that again.)

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