Author Topic: 100 metre memory  (Read 4948 times)

sammyh20

  • Newbie
  • *
  • Posts: 6
    • View Profile
100 metre memory
« on: February 16, 2014, 03:12:12 PM »
Hi folks could you explain this a little more to me..once you have determined the features on someone at 100 mtrs ..how do you estimate the distance?..do u send some one out for 100mtrs ...then gauge 100 mtr increments?..thanks once again

Hugh Westacott

  • Sr. Member
  • ****
  • Posts: 306
    • View Profile
    • Walk with Westacott
Re: 100 metre memory
« Reply #1 on: February 17, 2014, 11:55:43 AM »
Sammy

The great value of Lyle's book is that he has used his remarkable expertise, learnt navigating in all kinds of terrain, to bring together just about every navigation technique that there is. I've been exploring the UK on foot for well over sixty years and regard myself as a reasonably competent navigator, but have never used, or even heard of, some of the techniques that he describes. They all have their place but not everyone will employ them all.

I am not familiar with the technique of estimating distances based on facial features. I can see that it would work if you have reasonably good eyesight but not for me (a friend was unkind enough to remark that I would have difficulty in seeing an elephant at a hundred yards).

You tell us that you are new to map-reading and navigation and we are all eager to help you so I suggest that you work through the first few chapters of UNM, where Lyle teaches the basics of navigation, and leave the more arcane techniques until you have gained a lot more experience.

Good luck!

Hugh

sammyh20

  • Newbie
  • *
  • Posts: 6
    • View Profile
Re: 100 metre memory
« Reply #2 on: February 17, 2014, 05:07:05 PM »
Thanks Hugh that's exactly what I have been doing.This is my 4th weekend coming up ,and have been following the training sessions out of the book.My plan is to go to the white peaks this weekend ,which has some hills and start my understanding of contours and estimating distance ,hence my question about the 100 mtr memory.

Hugh Westacott

  • Sr. Member
  • ****
  • Posts: 306
    • View Profile
    • Walk with Westacott
Re: 100 metre memory
« Reply #3 on: February 18, 2014, 07:39:46 AM »
Good to know that you are working through the book systematically, Sammy.

As I've said, I've never used this technique and so am not able to give further elucidation. No doubt Lyle will respond in due course.

Hugh

captain paranoia

  • Sr. Member
  • ****
  • Posts: 384
    • View Profile
Re: 100 metre memory
« Reply #4 on: February 18, 2014, 06:08:55 PM »
Like Hugh, I can't recall many situations where I've estimated the distance visually for navigation purposes*.  I suspect the technique has uses for 'task-oriented navigators', who may be trying to describe where they are, or where someone else is, relative to their known position.  Search & Rescue teams, for instance.

For navigation purposes, it may be useful as a confirmatory technique "I'm 200m from the edge of the wood/landmark", which could be used to place yourself on a linear feature, although not with great accuracy (depending on the direction of the linear feature relative to the landmark).

Estimating distances from people in the distance assumes there is someone in the distance, and, for navigation purposes, that the person is somewhere 'navigationally useful'...

In conditions of fleeting visibility, and an unsure position, you might be able to briefly see and estimate the distance and bearing to an identifiable landmark.  Knowing the distance and bearing to the landmark, you can then make your way to the landmark using pacing on a bearing, even if the visibility then fades.  If you can identify the landmark on your map, you have now 'found yourself'.  And knowing where you are is the major part of navigating...

Generally, if you are navigating by map, and you are able to track your position on the map, then you need to be able to estimate distance from the map to the next waypoint/decision point/feature on your route.  Then you can make your way to that point by walking on a bearing, using time (knowing distance and your average speed) or pace counting.

I'll try to remember to have a look at the book tonight, and see if I can figure out the uses of this technique.

* I may have forgotten...

captain paranoia

  • Sr. Member
  • ****
  • Posts: 384
    • View Profile
Re: 100 metre memory
« Reply #5 on: February 19, 2014, 12:52:37 PM »
I had a look at the UNM last night, and I note that Lyle doesn't say why you might want to estimate distances...

So I had a look at what Wally Keay had to say (since I recalled he did mention it), and he suggested something similar to the lines I posted above; that of using distance to help identify landmarks (and, in particular, to help distinguish between them).  Though I'm not sure why you would want to; if you're able to use distance to distinguish landmarks, then you must be pretty certain of your position (otherwise you won't know what distance to expect).  And if you know your position, why do you need to identify remote landmarks?  I suppose you might identify your position by triangulating by distance (rather than bearing), like GPS or Loran does, drawing circles of estimated distance to landmarks, but Lyle certainly doesn't cover that in his book (and I don't recall any books ever suggesting it for conventional land navigation).

Maybe estimating distance is more useful if you don't have a map, and are exploring?  Then you can draw a map as you go, using your estimated distances, and measured bearings.

Oh, some 'navigators' might like to estimate distances for non-navigational reasons.  Let's replace 'distance' with 'range', and 'landmark' with 'target', for instance...  That might also explain the use of human features in the suggested range estimation technique...  Estimating range is important for a soldier, but not for a navigator (that I can think of), but I guess range estimation may well be taught within a military navigation course.

The problem with having learnt a lot of techniques is that you sometimes can't remember where you learnt them, or why they seemed useful at the time, but you think they might be useful to pass on...

Other suggestions for navigation use of estimated distance would be welcomed!

Lyle Brotherton

  • Administrator
  • Hero Member
  • *****
  • Posts: 939
  • Competent and safe navigation sets you free.
    • View Profile
Re: 100 metre memory
« Reply #6 on: February 22, 2014, 04:45:34 PM »
Spot on Captain as always:)

Ranging and estimating distance is an essential skill for all soldiers.

Every soldier must take into account Bullet Drop, which is the ballistic measurement of how far a bullet drops, normally at 100 metre intervals, were the barrel pointed perfectly parallel to the Earth. These corrections are called Comeups, expressed as full MOAs or 1/4 MOAs, you must "come up" in elevation to go from one range to another range in these 100 metre increments.

In addition, the soldier has to be able to calculate Lead: The side width of a human body is about 300mm and this is used to estimate how far the aim should lead a moving target. At 500 metres the aim must be 2xLeads ahead of a combatant walking and 4xLeads ahead of a combatant running.

Calling in Enemy Locations, especially in areas with no distinct land features, such as the desert areas in Afghanistan.

Ranging and estimating distance is also one of the reasons the military use the Mil instead of the Degree of which there are 360 in a circle. The military Mil is equal to 1/6400 of a circle or 3.375 minutes of angle. The mil is a handy measurement since it subtends 1 metre at 1000 metres and therefore facilitates range estimation.
« Last Edit: February 22, 2014, 05:47:04 PM by Lyle Brotherton »
“Opinion is the medium between knowledge and ignorance” - Plato

Hugh Westacott

  • Sr. Member
  • ****
  • Posts: 306
    • View Profile
    • Walk with Westacott
Re: 100 metre memory
« Reply #7 on: February 23, 2014, 01:47:54 PM »
Lyle;

Your reply to Sammy’s query has illuminated my mental darkness and made clear why I had failed to see the point of several of the techniques described in UNM.

I’ve not served in the military so, although I have a large collection of books covering land navigation for recreational purposes (walking riding & cycling), I’ve never read one intended for the armed forces. That’s why I could not understand what practical value, for recreational navigators, your descriptions for estimating distances had. I regarded them as mental exercises which, although interesting, would not be used in the field. Why, I pondered, do I, a recreational navigator for more than sixty years, need to know how to estimate 100 metres, or employ stereoscopic ranging techniques?

Another example is your apparent insistence on the primary importance of contours. I know, of course how valuable they can be when micronavigating in extreme conditions in mountainous country, but it seemed to me to be making navigation, especially in lowland countryside, unnecessarily difficult. Recreational navigators rarely use contours for route-finding in lowland countryside other than in the most elementary situations as, for example, when reaching a junction of paths and knowing that the required path runs uphill.

But your explanation has made me understand that contours in lowland countryside would be vitally important to a soldier who had to cross enemy territory without being observed. A recreational navigator does not have to be invisible and so is able to employ the much simpler method of navigating using the most obvious features which are normally field boundaries. Also, of course, the law in England and Wales requires recreational users (and the military for that matter!) to keep to rights of way, which makes contours even less relevant.

In future, when reading UNM, shall bear in mind that it was written for the benefit of all land navigators, civilian and military.

Thanks again!

Hugh

Lyle Brotherton

  • Administrator
  • Hero Member
  • *****
  • Posts: 939
  • Competent and safe navigation sets you free.
    • View Profile
Re: 100 metre memory
« Reply #8 on: February 23, 2014, 04:05:44 PM »
Hugh Westacott wrote: “But your explanation has made me understand that contours in lowland countryside would be vitally important to a soldier who had to cross enemy territory without being observed.”

Well Mr Westacott, you are absolutely right and I am not entirely right; allow me to elucidate.

Soldiers need to move with concealment, frequently with features in the landscape which have changed, even completely disappeared.

Buildings, even entire villages and towns can be completely obliterated off the map. Cities such as Hiroshima and Nagasaki had vast areas of population simply wiped off the face of the planet.

The destruction of war changes many things, yet fascinatingly, has little impact upon the topography of the ground with the exceptions of munitions such as bombs and mines – a mine is only a buried bomb.

Yet bomb craters are distinct and easily identifiable: during the conflict the earth is freshly exposed and the stench of the explosives can linger for months after the detonation. Even years afterwards, with examples from the fields of Flanders during WWI, their shape is so distinctive they can be easily identified.

Also they are relatively small. One of the largest non-nuclear explosions in history and the largest ever to occur on UK soil occurred at 11:11am on Monday, 27 November 1944 at the RAF Fauld underground munitions storage depot where an estimated 4,000 tonnes of high-explosives detonated.



This ordnance was stored deep underground, deeper than a bomb would penetrate, yet the crater formed from this massive explosion was only on average 240m in diameter. 

Even a thermonuclear weapon makes little change to land topography, primarily because to maximize the range of blast destruction (the pressure wave which radiates from the explosion) thermonuclear weapons are air burst detonition and these produce only shallow craters (mainly created by compression of the soil). The underlying topography of the land is compressed yet looks the same as before detonation.

A military route card looks very different to those we use recreationally, for those interested this is the one I instruct:

Estimated Travel time
Estimated Distance to Travel
Manoeuver room required
Trafficability
Load-bearing capacities of the ground to be covered
Tactical aspects of terrain – observation and fields of fire, cover and concealment, avenues of approach, protection from incoming enemy fire etc.
Ease of logistical support, such as MedeVac
Potential for surprising the enemy
Availability of control and coordination features
Availability of good checkpoints and steering marks
Energy expenditure by troops
Noise created in moving across the terrain

Contours are the mainstay of military navigation and augmented by features in the landscape which are unlikely to change in diminishing order, so starting with rivers and ending with paths.

However, in recreational navigation, boundaries, rights of way, trail signs, are of equal and sometimes greater importance than contours, particularly in lowland areas such as the Norfolk Fens.

I did not make this clear in the UNM Hugh and you are perfectly correct to point this out.
« Last Edit: February 24, 2014, 12:30:39 PM by Lyle Brotherton »
“Opinion is the medium between knowledge and ignorance” - Plato

Hugh Westacott

  • Sr. Member
  • ****
  • Posts: 306
    • View Profile
    • Walk with Westacott
Re: 100 metre memory
« Reply #9 on: February 24, 2014, 06:25:08 AM »
Yippee! Recreational navigator meets professional military navigator and they finally understand that they are both right; they were merely seeing navigation from different standpoints.

For my part, I knew that bullets had a trajectory but had no idea that it could be calculated in the field; nor had it occurred to me that the one stable factor when navigating was the terrain. I last handled a firearm in 1944 when, aged twelve, I played with my father's Lee Enfield 303 rifle when I was alone in the house. It was standard Home Guard issue during WW2 and was kept behind my parents' wardrobe along with a bayonet (no ammunition was kept in the house). I was not strong enough to hold the rifle properly and used to lay it on the bed aiming through the window at the house opposite. I can still smell the gun oil.

Next week I shall be making my annual inspection of the 25 miles of rights of way in the three parishes near Buckingham that I look after and report on to the Ramblers’ Association. Contours are at five-metre intervals and are few and far apart and to this recreational navigator seem insignificant, but I shall now look on them in a new light and try to imagine how a soldier might use them.

Thanks, again Lyle, for clarifying this for me. One more question; can you recommend a map-reading manual written for the military that is available to the general public?

Hugh

The desire for accuracy should not be confused with pedantry. Horace

Pete McK

  • Sr. Member
  • ****
  • Posts: 374
    • View Profile
Re: 100 metre memory
« Reply #10 on: February 24, 2014, 12:38:17 PM »
I too had not stopped to consider the different needs of different navigators, it makes perfect sense now.

Are there other navigational techniques used exclusively/primarily by the military?

And a leading question for you Lyle ;) I would be interested to know from your experience who make the better navigators: mountain rescue, recreational or military?

Hobbo

  • Newbie
  • *
  • Posts: 40
  • Man, likes camping, hiking and running.
    • View Profile
Re: 100 metre memory
« Reply #11 on: February 24, 2014, 07:21:42 PM »
It's also useful for determining how far away the pub is when you have line of sight.
I don't know it all and when I think I do, I tend to find karma is just around the corner...

captain paranoia

  • Sr. Member
  • ****
  • Posts: 384
    • View Profile
Re: 100 metre memory
« Reply #12 on: February 25, 2014, 12:30:25 PM »
> The military Mil is equal to 1/6400 of a circle or 3.375 minutes of angle. The mil is a handy measurement since it subtends 1 metre at 1000 metres and therefore facilitates range estimation.

The term mil is an abbreviation for milliradian.  Since there are 2.pi radians in a circle, there are 6283 milliradians in a circle, which is approximated to 6400 mil (64 is a nicely divisible number...).

The length of a circular arc subtending an angle theta (measured in radians) is simply l = R.theta.

For small angles, the linear distance between the ends of the arc tends to (i.e. becomes closer to, as angle tends to zero) R.theta.

So, if the angle is measured in milliradians, the distance between the ends of the arc is R.theta/1000, which is why one mil subtends 1 metre at a range of 1000 metres.  As Lyle says, this makes for very simple correction of artillery aiming; we estimate the error in shot fall, both in range and lateral offset.  From these estimates, we can easily calculate the required azimuth correction, and, using tables, correct the range by adjusting the elevation.

Lyle Brotherton

  • Administrator
  • Hero Member
  • *****
  • Posts: 939
  • Competent and safe navigation sets you free.
    • View Profile
Re: 100 metre memory
« Reply #13 on: February 28, 2014, 01:24:06 PM »
Pete Mck wrote: I would be interested to know from your experience who make the better navigators: mountain rescue, recreational or military?

‘How to Make Friends & Influence People’ is not a book I have read Pete, but I do know that answering your question is loaded!

However, since I have also not read ‘The Political Correctness Manual’ here is my unabridged reply:

The most comprehensive answer is anyone who practices land navigation enough and has a desire to be excellent will become an exceptional navigator. In mountain rescue, recreational and the military it is those individuals who do just this; so this opportunity exists for all of us :)

Of the many different types of groups, from the categories above, there is an interesting commonalty that links the very best of these navigators – Orienteering.

Orienteering is micronavigation on an extreme scale. The minute features they frequently need to identify, all against the clock, I find amazing. When I was working with a SAR team in Northern Sweden I was bowled over by their navigational proficiency and later, enjoying a few Pripps with the guys and girls, I learned that the entire team were also the local orienteering club.

Many of the military personnel who I train need to navigate without the aid of any electronic devices, sometimes even a compass (at night time) and their competency in stellar navigation, combined with terrain association, is first-rate.

I am also going to name the best navigator I have worked with: Scott Amos. In mountain rescue, on call outs in some very challenging conditions and on difficult terrain, his attention to the task in hand and navigational skillsets, which I have witnessed on several occasions, are outstanding and yes, he is also an orienteer (& Fire Fighter)
« Last Edit: February 28, 2014, 01:30:29 PM by Lyle Brotherton »
“Opinion is the medium between knowledge and ignorance” - Plato

captain paranoia

  • Sr. Member
  • ****
  • Posts: 384
    • View Profile
Re: 100 metre memory
« Reply #14 on: February 28, 2014, 02:22:17 PM »
> Orienteers

Hah!  That was my first thought...