Dartmoor survival – Navigation

One of the most important aspects of survival on any uplands area is the ability to navigate proficiently. I have certainly spent my fair share of time manipulating maps in the GIS & Remote Sensing Lab during university and from map exercises with 1st Port Isaac Cub Scouts (Don’t laugh, my mother worked really hard to set up and lead* the group … after I spent a good couple of months pestering her) but real navigational experience in adverse weather conditions cannot be underestimated.

Explore Moor with Dartmoor Search and Resuce

Last night was my first challenge since I became a probationary trainee member of Dartmoor Search and Rescue in October 2014. I had to plan a 2.5 hour circular jaunt from 532752, nothing especially complicated, I planned a fairly level route with a number of obvious tick point. I take approximately 60 strides on open moorland per 100m, covering the distance in around 1 minute. The catch, it’s February  at 50.55° N and I’m starting the walk at 19:30, it’s dark but thankfully we are currently experiencing a high weather system so it was still and fairly clear. A benefit of walking at this time of year as I soon discovered is that vegetation has died back for the most part and I was able to follow a direct bearing when required. Navigating around forest, boundaries and large features can disrupt your course, it’s not advisable to stumble straight into a disused quarry but thankfully I didn’t have to struggle through gorse (Ulex europaeus. if you’re unfamiliar with the species the modified 3cm leaf spines cause it to vary from a minor annoyance to an impenetrable blockade).

Dartmoor is intersected by a number of rivers and artificial leats, most are passable with care and can be easily differentiated on an OS map using basic geographic knowledge, rivers typically cut down through contours whereas leats follow them. The rivers and leads around the area I wished to navigate across made perfect tick points, I was able to verify my position as I came across them on my bearing at a practicable distance, sometimes very helpfully roughly halfway between my start point and objective. Other times I was able to walk knowing their relative location to my bearing and my objective, keeping in mind that if I was to come across them I had fallen offbearing or walked too far, thankfully this didn’t happen.  We came across plenty of features, rivers and trails that were not recorded on my OS Map but were able to dismiss them and correctly identify the ones that were. Sometimes local knowledge would have helped but the important thing about navigation is that it should be effectively carried out with relative ease regardless of familiarity with terrain.

Sometimes seeing anything in the dark can seem near impossible, Dartmoor is fairly accessible and hosts a number of settlements within the National Park itself. It is theoretically possible to alight oneself with the lights of settlements to help keep yourself on bearing, and as an additional bonus for the majority of the time from my location I was able to see North Hessary Tor transmitting station (4 red lights) and a secondary tower to the West (5 red lights). The one major problem with this is that traversing a landscape with such a huge contour variation is that the visibility of light sources may not be constant due to tricksey geological formations blocking your view. This of course is not a problem if you trust your compass and stay on course but one universal, at least on a good day, directional point common to all open areas is the appearance of stars.

Although I do not have the skills or equipment necessary to navigate on constellations alone, known as celestial navigation, as such would prove impractical however impressive when a constellation or point correlates with your compass bearing it is possible to follow that point on the horizon.

The constellations most visible, and indeed recognisable, last night were Ursa Major in the Northeast and Orion in the South. The North Star, Polaris, although present was, as it usually is, an un-noteworthy blip whereas Jupiter in the East proved beautiful as it guided the middle section of my walk.

The night as a success (I didn’t manage to kill anybody) and next week we are working on radio communication.

The Five Top Navigational Errors

These are the top five navigational errors made – guard against them and you have reduced your chances of an accident by almost 25%!

  1. Lack of concentration
    Clear thinking is critical for accurate navigation. When calculating moves use the Brace Position (kneel) to take you ‘out’ of the group. If navigating in difficult conditions tell the group you are not going to chat and instead concentrate only on navigation.
  2. Making the map fit the environment
    When you think that you have your position located on the map, choose a feature on your map, predict where you are going to see it and then turn in this direction to see it. If it isn’t there start your relocation procedure.
  3. Inaccurate compass bearings
    Always have the compass set in front of you and rotate your body, not the compass to your objective. If taking a bearing from a map always use the Brace Position.
  4. Compass Deviation
    Check wristwatches, karabiners, ice axes, ski and walking poles are all kept clear of your compass – even your jackets zip-pull!
  5. Forgetting to correct for Magnetic Declination
    Practice this so much that it becomes a conditioned reflex and you no longer have to think about it.

*As Chil, it was decided that a man, a coastguard, with actual outdoors experience would make a better Akela.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s