Navigation question, working out pace cards- Maths.

[Dave]

Ok, so I average 54 paces over 100 metres, which is 4mm on a 1:25k grid.

This is a simple enough sum, to work out any 25metre increment, {X} I simply multiply 54x {X}

So if X = 700 metres [28mm] I can multiply 54, by 7.00 = 378 paces.

So its easy enough to double this, to write a pace card, for a 1:50k grid, then double that again, for a 1:100k Grid.

But Ive just bought a harvey map, which has a 1:40k grid.

So, I know that over 200 metres, which is 5mm on a 1:40k grid, my average pace is 108 steps. [Twice 54]

To work out my paces with the 1:40k map there seems to be an additional calculation I need to perform. Namely to divide by 2.

[Because the pace chart on the 1:40k map rises by 40 metre increments, the figures jump from 80 metres to 120 metres.]

So to work out my average pace over 240 metres, I need to multiply 108 by 2.40 = 259.2 / 2 = 129.6 paces.

I think thats correct, just double checking.

Thanks.

 

[Dave]

No-one use harvey maps?

 

[bearbait]

I'd be inclined to keep it simple and just consider the actual distance on the ground inferred from the map and number of paces (e.g. 1.5km to creek crossing is 15 x 54 paces regardless of scale), rather than the number of mm on the map and number of paces varying according to scale. Much less to think about when you're tired/wet/cold/hungry, or some of them.

On longer legs I tend to use time and speed, particularly if there are any ascents or descents of significant grade.

 

[Dave]

I'd be inclined to keep it simple and just consider the actual distance on the ground inferred from the map and number of paces (e.g. 1.5km to crek crossing is 15 x 54 paces regardless of scale), rather than the number of mm on the map and number of paces varying according to scale. Much less to think about when you're tired/wet/cold/hungry, or some of them.

On longer legs I tend to use time and speed, particularly if there are any ascents or descents of significant grade.

Thanks, yes, Ill be doing that, but I plan the route beforehand on a route card, and there are places where I need to be very specific, so I take a write in the rain pad, with a pace chart I can glance at quickly, take a mag bearing, at an attack point, and know exactly how many paces it is to the next tick point.

So I want to know if my calculation for the 1:40k is correct? [Maths not being my strongest suite] As you know, 1 degree off, and too many paces and you can miss it by a wide margin.

Cheers.

 

[TinkyPete]

yes your maths is right for the paces but there are some things to take into account:

just a quick thing if you walk 54 paces in 100m is that without a load on flat ground because with adding weight and going either up or down hill your paces will change...

the paces count is always only a guide and will never be exact unles you permantly walk on level concrete, terrain will always be a factor.

but the map scale has very little to do with it....it is all about distance covered maps just show the terrain in a scale to suit the map. depending on terrain and your experience watch how long you have in each leg with out checking navigation, for example walking about in hilly or difficult terrain you do not want to have any leg longer than 500m in mountainous terrain that can go down to 100m. If mist or fog come down stop!! rest and have a brew and get out of the weather a bothy bag is good for that. But in open ground in good visibilty you can have legs around 1.5km it is all terrain dependant.

I have had to stop a group of walkers falling to their death on Ben Nevis; when the fog came down we stoppped and had a brew another group came up and thought they were travelling on a path, and kept on going we knew we had a cliff edge that was about 30m away and they kept heading towards it. we stopped them and asked they they thought they were, one of the guys got his map out and said showed us....he was about 500m out, we stopped and showed him exactly where he was and the fact he was at that point only about 5 meters away form a 800 meter drop... he was shocked and thought he was ok. they hunkered down with us and had a brew and then once the fog started to lift and we could see further than 30 meters we carefully and slowly led them up....the group I was with were all in the army as we were on adventure training and this was our last day after had walked the West Highland Way and within our group we had 3 military map reading gurus' of which I was one.

Paces Distance (m)
54 - 100
108 - 200
162 - 300
216 - 400
270 - 500
324 - 600
378 - 700
27 - 50
5 - 10
128 - 240


with paces parts are always rounded down and kept to whole numbers so you stop short of your destination and can see it rather than going past it.

Hope that helps

 

[Dave]

Yes, it does Tinkypete, cheers. I attended an advanced nav course with Mike Rushton at Tamarack. Another military guy. It was a very good course. We learnt about Naismiths rule, etc.
Just wanted to make sure my maths was correct on the 1:40k as Ive not used one before.
Its a 70 mile route, and I could buy one harveys map which covered the whole route, or 4 OS maps, at 1:25k, so obviously, cost wise I went for the harveys.

Cheers for confirming the math.

 

[janso]

As stated, your pace will definitely shorten with weight, terrain, incline and definitely decline ( imagine the shale face from Bristly ridge to the Glyder Fach in Snowdonia if you've been there.


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[Dave]

As stated, your pace will definitely shorten with weight, terrain, incline and definitely decline ( imagine the shale face from Bristly ridge to the Glyder Fach in Snowdonia if you've been there.


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Yep, Naismiths Rule, 4km per hour is the average walking pace, on level ground.
Grade 2 scrambles, reduce by 2km per hour. Walking into a headwind reduce by 1km per hour, wind behind increase by 1km per hour. In the dark halve your normal speed. If carrying a heavy load, say 20kg, halve your normal speed. Add one minute for every ten metre contour line. [harveys are 12m] Going downhill subtract 20 seconds for every 10 metre contour line and so on.

the actual speed Im not too bothered about. Its more the micro nav Im interested in.

Bit miffed that my silva ranger 15 tdcl doesnt have a 1:40k romer.

 

[SCOMAN]

Bit miffed that my silva ranger 15 tdcl doesnt have a 1:40k romer.

That might answer why not everyone uses Harvey maps! ;-)

 

[Brynglas]

Surely you're better aiming off and identifying your attack points with your micro Nav. It's all very well working out a pace count but I how are you going to factor in the effect that terrain has on your pace? I.e. Tussocks/ berms or other factors that might cause you to either shorten or lengthen your pace.

 

[Dave]

Surely you're better aiming off and identifying your attack points with your micro Nav. It's all very well working out a pace count but I how are you going to factor in the effect that terrain has on your pace? I.e. Tussocks/ berms or other factors that might cause you to either shorten or lengthen your pace.

Yes, sometimes I might aim off, or handrail down some feature. Certainly walking over tussocks, or muddy ground will affect my pace.

 

[SGL70]

This is interesting. I have never used paces in the aid of navigation. I will have to read up on this a bit...

(I normally roughly adjust the map to North, find a route with natural signs (ravine, brook, marsh, etc) that indicates that I have, or is about to, go too far in a direction, and head off. I almost never use a Compass)

EDIT: I did get lost in Barcelona once (Not enough maps, too many beers)

Greger

 

[Dave]

This is interesting. I have never used paces in the aid of navigation. I will have to read up on this a bit...

(I normally roughly adjust the map to North, find a route with natural signs (ravine, brook, marsh, etc) that indicates that I have, or is about to, go too far in a direction, and head off. I almost never use a Compass)

EDIT: I did get lost in Barcelona once (Not enough maps, too many beers)

Greger

Hi Greger, If youre about to go too far in one direction we call that a backstop. Paces are very handy if you want to find something, which you wont see unless you are right on top of it. Like an old mineshaft for instance. If youre on the right bearing, you have a little booklet which tells you that in exactly 475 metres you will fall down it, you just glance at your book, and know that its 256 paces away. You pace with one foot. So every time your left foot hits the ground its one pace.
You could use ranger beads, but a pace counter is more accurate.
http://www.thebushcraftstore.co.uk/pace--tally-counter-578-p.asp

 

[Crowe]

Pacing is good and accurate on the level to about 500 metres. But you're going to be spending all you time counting ! Better still is speed time distance equation. Much more accurate over 500 m and works with maps of any scale.

 

[bob_the_bomb]

Hi! Perhaps the most useful thing about pacing is that it helps you stop saying things like "take the second track on your right" when one season of forestry work could have added another entirely new track. It happened to me as a new soldier. A week later they taught us about pacing!


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