Author Topic: Overweight hiker navigation thread  (Read 1299 times)

ninthace

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Re: Overweight hiker navigation thread
« Reply #30 on: 15:42:17, 30/04/19 »
Yes, I know you can tell slope direction from the direction of the numbers and also it's obvious if there are contour rings nearby but once (maybe there were rings nearby and I simply wasn't looking for them) I'd assumed I'd keep going up when at some point it started going down.
The answer is usually, but not always - let me explain.  Your map will give you the bigger picture so you should be aware of where the high ground is which way the slopes are going and where the  folds in the landscape are - valleys and so on.  As you"zoom in" you have to retain this mental picture.  There are clues in the map - the obvious ones such as slope arrows on roads for example, or water courses which are usually, but not always, at the bottom of a valley - that sort of thing.  Then there are more subtle hints such as re-entrant contours which will indicate a gully and a down and up even if you do not actually cross any contours.  These things come with practice and experience, the ability to build a mental picture of the terrain.
That said you can get caught out in the short term.  Contours are either 10m or 5m apar.t.  It is useful to know which as ground can appear much steeper than it is if the contours are at 5m and you are used to 10 - Yes Tor on Dartmoor is a classic - on the OS map the contours are 10 on the sides and 5 on the N .  But I digress, the point is, if the contours are 10m apart, you can go down 9 and up 9 without cutting a contour.  Similarly I know of a section of moor by the Pennine Way near Middleton that looks fairly flat on the map but actually, has some substantial gullies in it.
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Rob Goes Walking

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Re: Overweight hiker navigation thread
« Reply #31 on: 16:07:42, 30/04/19 »
I prepared the route in ViewRanger although I will transfer it to a paper map before walking it. Don't see much to be gained by preparing it on paper first and I can easily see the elevation profile this way. Here's the link, 7.3 km. Steep but short bit near Witches Stride puzzled be for a bit, I thought I'd made a mistake but it's all good experience.

https://drive.google.com/uc?export=download&id=1aOmtybRrowW9eVrlPfaIX-opIErDsPxi

ninthace

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Re: Overweight hiker navigation thread
« Reply #32 on: 16:36:22, 30/04/19 »
The route by Witches Stride is along a old railway line - do you think it will be steep?
Look at the contours there - if the plot is out by the merest smidge you will either be half way up a cliff or halfway down the embankment!  Even more likely since your plot is a straight line between WP30 & 31 so it clips the cliff!
The second point is the accuracy of the source map you were using, how wide is a railway track in reality and how wide is it on the map if you apply the scale?  Now throw in the underlying elevation data which is not continuous and even if the point were bang on on the map, as drawn, the elevation data could still be out.
Sometimes you have to use a bit of common sense when interpreting a profile.  Let me give you an example - the SWCP runs along the edge of some fairly high cliffs.  Therefore the line between waypoints could pass over the sea which would show a fairly steep climb!  Even if you were to lay a live gps trace onto the map - the elevation profile can be gibberish, a 15ft error in a fix could put you 50 feet higher or lower than you actually were.


Points to take away - maps are a small flat representation of a large and complex 3D surface with all the limitations inherent therein.
Gps maps and data are not infallible either.
Common sense counts for a lot.


One last thing, look at your route between WPs 11,12 & 13, see the pecked line cutting the corner by the field boundary?  Which way do you think it is most likely to go?
In this case experience says it could be either since the green line wiggles but if it were straight, my money would be on the pecked line
« Last Edit: 16:43:27, 30/04/19 by ninthace »
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Rob Goes Walking

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Re: Overweight hiker navigation thread
« Reply #33 on: 16:53:29, 30/04/19 »
The route by Witches Stride is along a old railway line - do you think it will be steep?
...

Gps maps and data are not infallible either.
Common sense counts for a lot.


One last thing, look at your route between WPs 11,12 & 13, see the pecked line cutting the corner by the field boundary?  Which way do you think it is most likely to go?
In this case experience says it could be either since the green line wiggles but if it were straight, my money would be on the pecked line

It did cross my mind that railways shouldn't be steep and I did look at the contour lines there, while mostly they go around the railway a couple of them ran under it which I guess is an error of the railway being mapped since railways are flat in my experience.

As for the pecked line, I was distracted by the green line, didn't even notice it. Will try harder. :)

ninthace

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Re: Overweight hiker navigation thread
« Reply #34 on: 16:57:36, 30/04/19 »
It did cross my mind that railways shouldn't be steep and I did look at the contour lines there, while mostly they go around the railway a couple of them ran under it which I guess is an error of the railway being mapped since railways are flat in my experience.

As for the pecked line, I was distracted by the green line, didn't even notice it. Will try harder. :)
Map reading is all about subtleties  :)
Sorry forgot to mention, the railway through the woods is a good place for red squirrels.
« Last Edit: 17:00:40, 30/04/19 by ninthace »
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archaeoroutes

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Re: Overweight hiker navigation thread
« Reply #35 on: 19:04:42, 30/04/19 »
Adding to what's already been said, there are some little clues you can look at. Most become subconscious over time and you just look and 'feel'.
One of my favourites, because it is easy to teach, is:
V-shaped contours are Valleys and U-shaped contours are spUrs.
Of course there are plenty of exceptions both ways, but it usually works pretty well. Take a look at the field system between your route and the road (taking in Smardale Intake) and ignore everything outside for this exercise. If you walk south, is that uphill or downhill?






Clue: There are two sets of V-contours pointing south. Those are little valleys cut into the slope.










Answer: Walking south would be uphill.
« Last Edit: 19:15:52, 30/04/19 by archaeoroutes »
Walking routes visiting ancient sites in Britain's uplands: http://www.archaeoroutes.co.uk

archaeoroutes

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Re: Overweight hiker navigation thread
« Reply #36 on: 19:10:41, 30/04/19 »
I did look at the contour lines there, while mostly they go around the railway a couple of them ran under it which I guess is an error of the railway being mapped since railways are flat in my experience.
A contour line doesn't itself notate a big rise. It is the gap between them that denotes the 10m (or 5m or whatever). The loops of contour lines cutting across the railway could only denote a change of a few inches, just that it happened to hit the set altitude of the contour line.
Of course, the bigger factor is the cuttings and embankments shown which overide the countours.
Walking routes visiting ancient sites in Britain's uplands: http://www.archaeoroutes.co.uk

archaeoroutes

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Re: Overweight hiker navigation thread
« Reply #37 on: 19:14:28, 30/04/19 »
I've been caught out expecting the slope to keep going up and it suddenly goes down before.
Now this statement is a great sign that you are on the right tracks with your navigation learning. You expected something from looking at the map and noticed when the ground was different. This made you stop and work out what was happening, confirm that you were in the right place, and carry on.
Walking routes visiting ancient sites in Britain's uplands: http://www.archaeoroutes.co.uk

Rob Goes Walking

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Re: Overweight hiker navigation thread
« Reply #38 on: 19:25:21, 30/04/19 »
Archaeoroutes good point about the contours and as for cuttings and embankments I don't actually know what those are though I recognise them from the map key and thought of them as part of the railway line. I'll look up what they are after this post.

I hope I catch you while around :)

I wanted to triangulate my position today beyond a resection so tried to use my chinagraph pencils. Hopeless, the line draws 2mm away from the edge of the compass the pencil is too fat. I could sharpen it with a knife I guess but then I've got to carry a knife to sharpen it. Is there any good chinagraph pencils you recommend? The photographs in my book are of Staedtler brand pencils so I'll buy them next time if not.

ninthace

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Re: Overweight hiker navigation thread
« Reply #39 on: 19:42:26, 30/04/19 »
And just to show how reliable the OS can be, there is a map "error" just by the start.  The tree at NY 73997 08223 has four walls and a roof and has had since I first went there on 2011!.  OS maps are often years out of date in rural areas.  I have lost whole woods before now!  I once even came across a reservoir which wasn't on the map.  The terrain tends not to change though. 


For info: a railway line runs along the top of an embankment and through the bottom of a cutting.  Yet another example of  "fixing points"   Look at the embankment at NY 73644 08183 - it is at its widest here which means it is at its highest as it crosses the gill.  Similarly the end of the embankment at NY 71939 06092 just N of Smardale Bridge acts as a fix.
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ninthace

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Re: Overweight hiker navigation thread
« Reply #40 on: 19:43:08, 30/04/19 »
Archaeoroutes good point about the contours and as for cuttings and embankments I don't actually know what those are though I recognise them from the map key and thought of them as part of the railway line. I'll look up what they are after this post.

I hope I catch you while around :)

I wanted to triangulate my position today beyond a resection so tried to use my chinagraph pencils. Hopeless, the line draws 2mm away from the edge of the compass the pencil is too fat. I could sharpen it with a knife I guess but then I've got to carry a knife to sharpen it. Is there any good chinagraph pencils you recommend? The photographs in my book are of Staedtler brand pencils so I'll buy them next time if not.
  Try a water-based fibre tip pen - in the good old days we used those in the RAF.
« Last Edit: 19:48:31, 30/04/19 by ninthace »
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Rob Goes Walking

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Re: Overweight hiker navigation thread
« Reply #41 on: 20:00:48, 30/04/19 »
  Try a fibre tip pen

Maybe. Everyone else is using chinagraph pencils but my lines are 50 real metres out on the 1:25000 maps. Perhaps I'm being [censored] and 50 m isn't a big deal in practice?

ninthace

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Re: Overweight hiker navigation thread
« Reply #42 on: 20:09:51, 30/04/19 »
Maybe. Everyone else is using chinagraph pencils but my lines are 50 real metres out on the 1:25000 maps. Perhaps I'm being [censored] and 50 m isn't a big deal in practice?
  They are?  I for one haven't drawn a line on a map for years except in the form of a route.  The alternative is to print your map out then you could use 2B pencil (rubs out easily), like real navigators do, and keep your big map clean.

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Bigfoot_Mike

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Re: Overweight hiker navigation thread
« Reply #43 on: 20:12:53, 30/04/19 »
Maybe. Everyone else is using chinagraph pencils but my lines are 50 real metres out on the 1:25000 maps. Perhaps I'm being [censored] and 50 m isn't a big deal in practice?


50m off laterally would make a big difference on Crib Goch or Striding Edge, but you would notice theat you were off course way before this by the rushing sound in your ears.

Rob Goes Walking

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Re: Overweight hiker navigation thread
« Reply #44 on: 20:28:15, 30/04/19 »
  They are?  I for one haven't drawn a line on a map for years except in the form of a route.  The alternative is to print your map out then you could use 2B pencil (rubs out easily), like real navigators do, and keep your big map clean.

The book teaches chinagraph pencils and archaeoroutes mentioned them. I'll consider printing my maps but it will be a pain to draw on in the rain and I did want to triangulate as practice even if I'll probably do little of it "in anger".