What are Collecting and Catching Features in Navigation?
And what does thumbing the map mean?
CATCHING AND COLLECTING FEATURES – THUMBING THE MAP
When people use the terms catching or collecting features, and I am thumbing the map – what do they mean?
Micro navigation breaks the journey down into small legs. The legs get smaller as the conditions and visibility worsen, so you do not go off course before getting another accurate fix of your position.
At the end of your leg is your attack point, a feature you are heading for that is hopefully prominent and unique in your location.
Heading off to your attack point is fine, but in poor visibility you need to regularly check you are on track, and stop if things do not add up. That is where collecting and catching features come in.
Before you head out on your next leg, look at the map and describe to yourself (saying out loud can help) what you expect to see on the way.
“Heading gradually downhill, open moor, should be a stream appears from my left in 50m, then I should see a sheepfold on my right after another 300m”.
You are collecting features as you go. In this case the descending ground, the stream and the sheepfold.
If the ground is rising steeply, or flat, you will recognise you are going wrong. Similarly if the stream or sheepfold do not materialise as expected you may be off course. This allows you to stop and reassess before you have gone too far.
An easy way to do this is to keep your thumb on the map under your location and gradually move it up as you pass your collecting features. Put it under the stream then move it under the sheepfold as you progress. That way when you look down at the map instead of hunting with your eyes for your location, you simply always look above your thumb as you are ‘ thumbing the map ‘.
Often people under or over estimate their speed and progress. You cannot assume you will always be doing Naismith’s 4kmph and 1 minute for every contour climbed etc, on every walk you do. Tiredness, weight carried, terrain, weather and wind, fitness, visibility etc all have an effect on your speed.
To help with this, try to choose an attack point that has a really clear prominent feature behind it that will catch you from going too far. For example a stream, track, path or wall crossing your route; even descending or rising ground is usable to easily detect that you may have gone too far.
A catching feature will catch you from overshooting your attack point by far. But be careful, streams can dry up, fences or walls can be knocked down, so use timing and pacing too in order to check how far you have travelled.
In this example we are heading for the track which is our catching feature and also our attack point at the end of this leg.
A catching feature to show that we have missed our tent (below) is that the ground will flatten then start to descend.
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Mend Our Mountains, Fix the Fells, John Muir Trust and Mountain Bothy Assoc.