Navigation Insights For Marmot Dark Mountains™

2nd Jan 2018

The 2018 Marmot Dark Mountains™ is the 6th edition of the event and it has steadily grown since its winter storm baptism in 2013. It is now widely considered the benchmark test for all-round mountain craft for experienced mountain runners. The combination of darkness and winter conditions combine to make Marmot Dark Mountains™ a unique challenge for participants, where usual mountain running approaches to navigation, and equipment and clothing choices can prove to be inadequate. Stepping up to the challenge of this event requires new skills, different strategies and alternative clothing and equipment. Here, Marmot Dark Mountains™ Race Director Shane Ohly, shares some of his insights for success drawing on his experience as a multiple Elite mountain marathon winner and Winter Mountain Leader. 


My preferred style of navigation is an intuitive approach. I prefer sensing the contours, visualising features from the map and then identifying them as I move through the terrain. Done well, this is a fluid style of navigation as opposed to a more traditional approach of taking bearings, estimating distance, and even pacing. However, there is definitely a time and place for a more structured approach to navigation. 


Let me share a vivid memory of my Winter Mountain Leader training, which I hope will illustrate the different challenge winter and darkness bring to the navigation game. I was asked to locate a stream junction about 1,200m away on the Cairngorm plateau. It was the middle of the night and there was two metres of snow lying on the ground. This meant ground features, like the stream, were completely obscured. In summer conditions an approach to locating this stream junction would be to aim off. Aiming off means deliberately taking a bearing 1-200m to the right of the stream junction, and simply turning to the left when the stream was reached, and continuing along the stream in that direction until the junction was visible. At night this tactic should still work, but throw in the winter conditions and you need a different approach. 


Given the darkness and snow, the correct approach now is to measure the distance accurately, take a careful bearing and then time or pace to the location. When you arrive, there are likely to be no visual clues that you are in the correct location, and the next important skill is required; dead reckoning. When navigators talk about dead reckoning, they mean that based on their previous known location, the known distance covered and the known bearing, they know precisely where they are now, despite a lack of any visual clues. 


Back on my Winter Mountain Leader training, I arrived at a featureless patch of snow, and had to confidently tell our instructor that I was stood exactly on the spot of the stream junction. As this was training, the instructor produced his GPS, and asked the group to gather round and say where they thought they were…


What does this mean for participants at Marmot Dark Mountains™? Well often when we see significant navigation errors as revealed by the GPS tracking, the participants may not have taken a systematic approach to attacking the checkpoint. The real skill is knowing when you can rely on the faster ground interpretation approach, and when you need to switch to a slower and systematic approach. In a real-world example, here is my GPS track with an explanation of how I have broken down the navigation from a wintry run over Ben Wyvis completed in very poor visibility just a few days ago. 



Leg A Plan: I am following the main path to the An Caber summit (946m)
Leg B Plan: White out conditions from now. Short leg dropping to a col and then climbing to flat ridge (the flat ridge is my next attackpoint). Distance: 800m. Time: 10 minutes
Leg C Plan: Follow ridge to summit trig (the summit trig is my next attackpoint). Distance: 1,400m. Time: 17 minutes
Leg D Plan: Drop down to the col (the col is my next attackpoint). Distance: 1,100m. Time: 11 minutes
Leg E Plan: Climb to the flat ridge (the ​flat ridge is my next attackpoint). Distance: 400m. Time: 5 minutes
Leg F Plan: Follow ridge to summit cairn (953m) (the ​summit cairn is my next attackpoint). Distance: 300m. Time: 3 minutes
Leg G Plan: Follow the ridge down to the col and 742m spot hight. You can see I drifted off my bearing here... nobody is perfect! The important thing is the correction. 
etc. Hopefully this example is helpful.


At Marmot Dark Mountains™ we utilise GPS tracking which significantly enhances safety management at the event, but it also reveals the different approaches in participants' navigation strategies. Often we see participants' GPS tracks darting around in random patterns close to a checkpoint; the participants clearly know they are close, but they don’t actually know where they are and therefore where the checkpoint is. 



Marmot Dark Mountains™ 2017. The red line shows an intuitive 'orienteering' style approach, and the pink line shows a systematic style.


Let me share an excellent example from Marmot Dark Mountains™ 2017 (above). An experienced participant was taking a bearing towards a hill top, with a sheepfold checkpoint on the other side below the hill top. The hill top was marked with a cairn.  As they approached the hill top, they intuitively contoured around the hill saving height but avoiding the cairn attackpoint, and taking a higher risk route to the sheepfold. In terrible conditions (darkness and fog), they missed the checkpoint and began a long search for the elusive sheepfold wasting approximately 15 minutes before it was found. Being harsh their errors were:

  • Overall, an intuitive rather systematic navigation strategy
  • Not visiting the cairn as a definite attackpoint
  • Not knowing the distance they have gone once they contoured the hill side
  • An intuitive search for the sheepfold 


Early the following morning, still with terrible conditions, one of our experienced Event Team members was collecting in the same checkpoint. He is also a Winter Mountain Leader and adopted a very different, a more systematic approach: 


Approaching the hill, he continued to the summit rather than contouring around the hill, and passed the summit cairn (literally a rock solid attackpoint). After a bearing adjustment from the cairn, he continues on a short leg to towards the Sheepfold. Using dead reckoning he stopped within 50 meters of the sheepfold. Knowing he had walked the correct distance from the cairn, on the correct bearing, he was therefore certain that the sheepfold must be within metres and simply started a spiral search outward, finding the sheepfold in less than a minute. Two very different approaches! 


So the take home message here is that when the conditions are really very poor… like in the middle of the night, and with snow on the ground, if you don’t want to rely on luck, you need to adopt different strategies to your usual summer navigation. That approach is to use rock solid attackpoints, take careful bearings, measure distance accurately and then pace and/or time your approach to the that attackpoint if required. I would also strongly advise using the shortest possible legs between appropriate attackpoints i.e. use big, linear features if you need to.


Top Navigation Tips

  • Get a pace/timing card: Navigator's Timing Card
  • Kneel to take a bearing (see next article about Clothing & Equipment for example)
  • Think 3D: Direction, Distance, Duration 
  • Use solid attack points
  • Use ‘Aiming Off’ frequently
  • Use ‘Dead Reckoning’ rarely
  • Break down each section into short legs


Good luck out there!