Nav Work 103 - Pacing, Obstacles, and Nav-Nerds

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Lurch
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Nav Work 103 - Pacing, Obstacles, and Nav-Nerds

Post by Lurch » August 6th, 2013, 5:15 pm

Nav Work 103

Super Amazing Navigational Techniques for the Navigationaly Challenged and Challengers!

Previous Threads:

Nav Work 101 - Cardinal Directions and Declination
Nav Work 102 - Crazy Magnets and Stuff

We talked long and hard about Declination, and compass use in the previous thread. Also discussed shooting and taking bearings, so I guess it's time to actually put some of that to use!

Pacing
There are a few ways to tell distance in the wilderness. One of the "easiest" methods (without the use of a GPS) is with simple pacing. This has been used for thousands of years. For the finer distances you'll use your steps, for longer distances it's often easier to have an idea of your average MPH in the given terrain, and guesstimate your distance base on the time traveled.

Personally, I teach pace based off a 100' baseline. There are a number of reasons I have for doing this, since the majority of distances I may be required to pace off will commonly be well under 1/4 mile, and I typically have other tools to measure things at a longer distance. You could also learn your pace for 100 yards, or even 100 meters. They're all perfectly viable systems and if you go metric there are undeniable strengths in the versatility of the system, it enables to the use of slightly more logical pace beads for example. However most trails aren't measured out in Km, and constantly converting back and forth in your head can be tedious.

Either way Pick a system that you would prefer, stick to it, and learn your pace. This could easily be done on a track or football field for example if you want a longer pace, or using a tape measure / rope to mark out 100'. Be consistent in your system. There are possibilities for error in this method from a thousand directions, so consistency in your training and practice is going to be key to getting remotely reliable results. Try this in all different types of terrain / slopes / vegetation you may be needing this skill, they'll all give you different numbers and you'll start to learn the characteristics of your individual pace.

Generally speaking, your Pace is two Steps. If you lead off with your left foot, you could count Left -> Right (one) -> Left -> Right (two) -> Left -> Right (three)... As you could imagine, this would get rather tedious if you wanted to pace out multiple miles. I would say the average pace for 100' is somewhere around 20. That would put you at 1,056 paces to the mile. I don't know about you but I would rather *not* repeatedly count to 1,056 in my head as I hike. Which system you use is really going to be dependent on what context you'll be needing it in, so I will leave that up to you and do my best to give you the general underlying principals behind it.

You can start to see the major differences when you look at some different units

100ft = 20 Paces
100Yd = 60 Paces
100m = ~65.5 Paces
1/4 Mile = 264 Paces
1/2 Mile - 528 Paces
1 Km = ~655 Paces
1 Mile = 1065 Paces

You could easily make up a chart for whatever your pace comes out to, but there are a few things to keep in mind while doing this. Your accuracy will always come down to consistency, and practice.
  • Wear your normal clothing and equipment you'll be using. Your natural stride will change with what you're carrying
  • Moderate uphill will shorten your pace
  • Moderate downhill will lengthen it
  • Steep downhill will shorten it again
  • On trail, vs cross country will alter your average
    • Obstacles, like climbing through blow downs will obviously screw you up. In these cases it's good to pace between your bearing points and take notes instead of attempting to keep the overall tally in your head
Bearing Obstacles

So now we've got your bearing technique, and pacing down. I've had a few questions about how to deal with major obstacles in your path and stay both on bearing, and on pace. Lets go over a couple practical real world methods for both, and then I'll share one of my favorite impractical uber nav-nerd tricks. Most all of these things can be figured out using less steps if you're a fan of Trig. But for those that aren't we'll go the simple way :D Please pardon the MS Paint graphical wonderness here..
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Lets assume you are the Star, traveling on a 0°T (North) bearing along the purple line and have run into a pond that you would rather not cross. This could be because you don't want to swim, or maybe your pace is important and you need an accurate accounting of your distance.

If your pace doesn't matter, but you need to stay on bearing than the simplest method would be to find a target on the opposite shore that is along your bearing, and simply walk around the shore to your new target.
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Unfortunately that method doesn't always work, or isn't as easy as it sounds if there isn't a clear and identifiable target on or near your bearing. One potential (although some would say un-ideal) solution for this is some simple flagging tape that will be visible from the other side of the obstacle. Or to be more nature friendly, build some sort of cairn you'll be able to see from the opposite shore. Then you can simple walk the shore, and shoot your a bearing back to that carin until it falls along your back azimuth (the opposite direction of your bearing, or 180° off). Once that's in line, you know you are back on your original path and you can proceed as before.

If your pace is vital, then your options are somewhat more limited. Again, there are a bajillion ways to do this, but this is one of the easiest to actually put into practice without excessive mental work. The main concept is that if your original bearing is not passable, but it would be passable parallel to it on either side, then you simply hop over, and hop back.
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In the example above, you are again at the star, the pond is in your way and you want to maintain your pace. It's just four simple steps!
  1. Take a new bearing 90° off of your original (we're going to make a box here). In this case we are heading north, and will divert to the west, so we will take a bearing of 270°T
  2. Continue along this bearing until you are beyond the obstacle. Remember the bearing and the distance you diverted!
  3. Return to your original bearing, walk until you are beyond the obstacle, and add this distance to your cumulative total
  4. Once clearly past your obstacle, you'll turn the opposite 90° and return the distance you diverted initially to your regain original azimuth.
This is obviously extra easy because we're dealing with nice square bearings falling on the cardinal directions, but it works with anything, just make sure you're precisely 90° +/- of your original, and then close the box when you're done with the diversion. This is a useful system, because you do not need to maintain any sort of visual connection with the original points. You could walk WELL outside of the obstacle and still retain an accurate accounting. You could even stack multiple diversions on top of each other as long as you're keeping track and can 'undo' all the steps back to the original bearing.

To be completely honest, most of you guys will not need to rely on pacing often, however in the above circumstance knowing how to do your pace is essential to successfully pulling it off correctly.

The Nav-Nerd example is a straight up geometry put into real world practice. Say we want to figure out the distance across the river, from our location (the star) to the opposite shore (Green Dot)
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We're going to solve this dilemma with some similar triangles and some help from the almighty Pythagoras. We're going to call the distance from you to the green dot side A. We'll then walk perpendicular to that bearing for a random distance and call this side B. This distance can theoretically be any distance you want, however round numbers are nice, and something close to your guesstimation of the distance is going to make you more accurate in the long run.
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You're going to mark where ever you decide to stop, and shoot a bearing back to the Green Dot. This will complete your first triangle. Remember this bearing! You'll need it in the near future for verification, but you're going to essentially repeat the process again. Doing a perpendicular bearing to side B, to create side a of the second triangle, turn and complete side b until you can shoot a bearing through the previous corner, and back to the original Green Dot.
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Now it's just a matter of some "simple" math, assuming you've been keeping track of your distances! Since the two triangles are directly proportional, (if your bearings are good) you can safely assume that sides A/B = a/b

To break that down a bit more, we're looking for length A. I'll make up some numbers for the others so we can work through the math. Lets assume the following:

B=100'
a=35'
b=42'

From that we can say that A/100 = 35/42

A/100 = 0.83333...
A=83.3Ft

We can get into using Trig to tell heights of cliffs/trees if you guys are interested in that, but I think I'll end this thread here for the time being. Apologies for the massive delay between this one and the last, been a busy year to say the least!

Next one we'll get into using Topo maps and how to shoot/take bearings with your compass on them!

Questions / Comments / Concerns / Critiques?? (I typed this one up while I was at work, shhhhhh don't tell!). I appreciate any sort of feedback, it's good to know if these things are helpful to anyone in the slightest. If they are then I'll keep them up

Cheers! Keep Calm Hike On! :lol:

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Crusak
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Re: Nav Work 103 - Pacing, Obstacles, and Nav-Nerds

Post by Crusak » August 6th, 2013, 6:08 pm

Excellent!

I can already tell that I would benefit from some formal navigation training. But I wonder how much I would retain? Any tips on ways to remember how to do some of these things? Maybe just putting the concepts into practice even when you don't need to?
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RobFromRedland
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Re: Nav Work 103 - Pacing, Obstacles, and Nav-Nerds

Post by RobFromRedland » August 7th, 2013, 5:33 pm

This one was useful to me. Maybe not as useful as the others, but it was a good refresher. I'm looking forward to the next installment.

Thank you for taking the time to do these.
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Lurch
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Re: Nav Work 103 - Pacing, Obstacles, and Nav-Nerds

Post by Lurch » August 8th, 2013, 12:17 pm

Glad they've been helpful :D

Crusak: I've been very disappointed in a lot of "professional" navigation training. instructors tend to get so focused on the Boy Scout or primitive survival style "tricks" to make them sound knowledgeable and impressive that it clouds the fundamental skills that are needed and would be used the majority of the time. Yes you could make a compass with a needle some silk and a leaf, but do you really need to be able to? You could find an E/W line with a stick and a shadow if you had half a day to waste, but is that the most effective use of your time and energy?

As for the skills above, and in the previous (and future) threads, nav is most definitely a perishable skill. Paces will change, techniques will falter, and if you don't practice at least until the fundamentals are ground into you the general concepts can get wonky in your head.

To actually make pacing practical, over longer distances you'll want to make yourself a set of pace beads. They're simple to make with some spare parachute cord and some beads

Image

These are also know as 'Ranger Beads' and generally speaking these are used with the metric system, since the base 10 system is a wee bit easier to comprehend. The beads in the image above are designed for that for example, but I'll explain the setup for a mile based set to measure out 5 miles at a time

Essentially this is your trail abacus. The beads are split into two sections, where they upper set will be complete miles, and the lower set will be the fractions. For miles it's usually easiest to split it into 1/8 mile sections. These commonly hang off the shoulder strap of the pack, and can easily be manipulated one handed without too much effort, they are also tactile enough you can check your distance by feel, without having to see anything. (another reason the military likes them)

Since we're going 5 miles with this set, the top section will have 5 beads. The lower section is measuring 1/8th mile, so there will be 7 beads on that. You start zero'd out with all beads in the up positions

XXXXX---|XXXXXXX----|

If we stick with the earlier guesstimate that your pace is at about 20 paces per 100', then 1/8th mile would work out to 132 paces. That's a countable number without going completely insane. Of course you could (and should) tweak this system to your personal pace and needs, and it will work with any fraction of a mile you'd like to go with, you'll just need to change the numbers as needed.

After 132 paces (1/8th mile) you would slide down the bottom bead of the lower section, and start counting again.

XXXXX---|XXXXXX----X| = 1/8th

This would continue along until you're at 7/8ths of a mile and have all the lower beads down.

XXXXX---|XXXXX----XX| = 1/4
XXXXX---|XXXX----XXX| = 3/8
XXXXX---|XXX----XXXX| = 1/2
XXXXX---|XX----XXXXX| = 5/8
XXXXX---|X----XXXXXX| = 3/4
XXXXX---|----XXXXXXX| = 7/8

On 8/8ths you would drop the first mile bead, and move the fractions back up

XXXX---X|XXXXXXX----| = 1 mile

Start out with some of the shorter trails, or practice between trail junctions and try and pace it out to see how accurate you can be. There's plenty of landmarks out there that are easy enough to track you can practice and test yourself so you're good to go during those other times when you need the skill

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Koda
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Re: Nav Work 103 - Pacing, Obstacles, and Nav-Nerds

Post by Koda » August 8th, 2013, 2:15 pm

Question: How is knowing the distance across a river helpful? …your either going to cross it or not and the deciding factor is how dangerous it would be to do so…

Compliments: The pacing subject is very helpful to me when put together with diverting obstacles off trail. Several times I have had to circumnavigate bearing obstacles that are not so straight forward as a lake or pond…. Like a bog or swampy area, impenetrable brush, or a small but difficult enough cliff band that didn't show up on the topo. Anyways, I've relied on the box method you described but never accurately paced myself. Most times I came close enough to continue, but on one occasion I got off track enough that ‘technically’ I got lost. What I learned was how surprisingly small a diversion can be that can get you so far off your bearing to become an issue.

Suggestion: maybe another thread specific to obstacle navigation, maybe call it Advanced Obstacle navigation where it can cover other methods to rely on as well as the box method.

Also, a topic on ‘getting back on track’ would be useful. In the aforementioned ‘lost’ situation I was eventually able to get back on track by reading the terrain, and comparing it to the topo. I was able to estimate my position well enough to set a new bearing to my original destination and continue on. I can elaborate if needed, it wasn't so simple.
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Lurch
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Re: Nav Work 103 - Pacing, Obstacles, and Nav-Nerds

Post by Lurch » August 9th, 2013, 1:32 pm

Well like I said, that was mainly just an intellectual navigational nerdery exercise to get people to start thinking about nav in general as a flat piece of paper geometry problem, and try to ignore the fact that you're in the woods and dealing with the elements.

That said, being able to determine a distance between two objects without actually measuring it off *can* be helpful, although it's legitimate use is somewhat limited. When it comes to canyoneering, river or rope rescue stuff, if you need to get a line across for a Tyrolean traverse or some other activity that line distance is going to start to factor into calculations. In all honesty I've never *needed* to use that triangle method, but getting people to think geometry instead of navigation can open up some common sense things to allow them to figure out a solution to a surprise scenario.

Navigation is almost always going to have some inherent error in the system. We do our best to mitigate that, and control to be as accurate as possible, but if you're keeping within 2° of your target I would say you're doing well. 1° error, over a 1 mile length will put you off by roughly 90 feet.

One of the exercises that I give people is a type of compass course, where they will get a series of bearings and distances. There's nothing in the field to find, they are just supposed to walk along that bearing for the given distance, stop, then do the next one. The last leg of that can be held back in order to have them find the bearing and distance to return back to their starting point. This doesn't require any "setup" prior to, and can be conducted just about anywhere from a parking lot to the middle of the woods. For example:

189ft @ 354°
208ft @ 131°
334ft @ 185°
445ft @ 320°
185ft @ 109°

That course is a bit over 1/4 mile total, and should end up in the same spot that you started. I would usually leave the last leg off for them to tell me the two variables.

If you are shooting for absolute accuracy, there are a number of techniques you can use but they can get a bit intense and time consuming. Rather the 'common sense' methods of nav, of simply getting from point A to point B are probably most applicable to people here. In that sense, I would rarely advise someone shooting directly for their target.
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This may seem counter intuitive, but it's fairly safe to assume you will at some point have some error in there. Say you are the star, trying to meet your buddy at the red diamond along a trail, and it's a couple miles away. So you take a bearing directly to them, and start walking. You're bound to hit the trail at some point, but when you do there's no buddy to be seen. Now you're left with the decision to head either East or West, but which one is correct? If you introduce an intentional offset of about 10°, and purposely shoot for one one side or the other you have a good idea which way to go when you hit your containment.

This concept holds true for a number of things, and we can get into some of that when we start talking about maps in the future. Most trails on the maps are roughly in the right place, but not completely accurate. Shooting for the *end* of a road is a bad plan because not only could you miss it entirely, and not have any containment line to stop you from walking well past it, but the end of the road may or may not actually be where you think it is.

When I'm going somewhere, or if I am sending (or looking for) someone into the wilderness I'm going be checking the map for 'containment' boundaries. Some people call these Catches, but essentially it's that obvious feature that you couldn't possibly pass without missing it. This could be a creek, road, trail, cliff band, or similar thing. In the picture above simply heading North would run you into the trail at some point. I like to establish a 'bugout bearing' that shouldn't be anything too specific that you couldn't follow it in a hypothermic drunken haze, but will take you to a control point where I can orient myself and know exactly where I am in case my plan isn't working out.

When you get into some more 'terrain association' based techniques, you can also use 'handrails'. These generally rely more on map and terrain reading than on compass skills, which is why I didn't put them in this thread originally, but they allow for an easy route to follow. Trails and roads are obvious hand rails, but ridge lines, fences, creeks, ditches, etc can all establish a line that you can follow, or walk beside. It's not even necessary to be *on* the hand rail, most people can maintain a a pretty consistent distance from something if they have a good visual. Being able to find two hand rails that intersect will allow you to follow one and establish your known position. You can start to collect these things, and various other land marks to create a good mental picture of where you are in relation to them, and where they are in relation to each other.

If you get hopelessly off course, but still want to continue to a miscellaneous target out in the middle of nowhere, you could bugout to a control line, figure out where you actually are and re-establish a bearing from a slightly different direction. All that takes map work though, which we haven't gone over yet ;)

As for re-finding yourself while you're just following a bearing, it really comes down to choosing your targets wisely as you leap frog along. You need something identifiable, even if you loose sight of it. If there is nothing actually on your bearing, but there's something close to it you could use that too and hope that you can guesstimate how far off you need to be.

If you are going from tree to tree, that's fine, but make sure you're putting yourself on the opposite side of the tree before reshooting your bearing, not just standing to the left or right. If you walk up to your target, them move 3' to the left to shoot your next bearing, and continue that dozens of time those 3's start to add up quickly.

You'll also want to take a look at your previous target, from the other direction when you're leaving it, so you can return to it if you lose yourself and need to attempt that leg again. If I'm in a stupidly consistent groomed forest without any identifiable marks (think like an aspen forest) then it's not a bad idea to stick a broken branch in the ground, or some other simple, but natural, non-destructive, and identifiable mark every time you finish a leg. I'm not recommending blazing a tree, or even putting up flagging tape, although in a full on emergency do what you need to do. If you aren't sure you're at the right target tree when you finish that leg, you can shoot a back azimuth back to the last point you knew you were on track. If that doesn't line up then you have a problem, and you either need to re-attempt the leg, or move over until your back azimuth is correct.

If you aren't going solo, and you have another person with you navigation can become a lot easier! Leap frogging with someone else can be as simple as sending them out, and taking a bearing off of them, having them move left or right as needed to stay on your line. This can get you around obstacles if you can see across them, and it's one of the easiest ways to actually run a bearing at night where you can focus on a head lamp or other light source, instead of shooting a bearing to that dark tree that looks exactly the same as the 4,000 other dark trees in front of you.

When I do the map/bearing one we talk talk about triangulation, or intersection vs resection for you military types.

No idea if that ramble helped or made things more confusing... :?

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retired jerry
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Re: Nav Work 103 - Pacing, Obstacles, and Nav-Nerds

Post by retired jerry » August 9th, 2013, 1:59 pm

Thanks for your posts - 101 and 102 also

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Koda
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Re: Nav Work 103 - Pacing, Obstacles, and Nav-Nerds

Post by Koda » August 9th, 2013, 2:59 pm

well, that was a keyboard full Lurch, but quite useful. Confirms some things I'm already doing. I almost always intentionally offset a bearing if its on a trail or other handrail.

thanks for posting these... I'll give your keyboard a rest from questions. ....for now. :)
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Re: Nav Work 103 - Pacing, Obstacles, and Nav-Nerds

Post by Lurch » August 13th, 2013, 9:32 am

Questions are always good :D these posts are boring for me unless there's some sort of discussion afterwards! It's such a broad topic it's hard to give specific answers. Besides, you guys asking questions helps me refine my information and techniques a bit, definitely a challenge to relay some of these skills through text and not in person!

I do tend to ramble a bit though, if my posts aren't making sense then speak up.

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Re: Nav Work 103 - Pacing, Obstacles, and Nav-Nerds

Post by raven » August 13th, 2013, 6:49 pm

I think accuracy in using a map and compass is overrated as a skill. By accuracy I mean any effort that depends upon a 1 or 2 degree precision.

I don't believe I remember anyone mentioning compass calibration. Want to bet you can read yours to one degree and actually have the correct bearing? I don't.

It's not that it can't be useful, but its usually more of a game than a useful skill. Before a trip into northern Alaska, my companion asked for a compass check. (We both had Silva Ranger sighting compasses.) We disagreed (convenient pun) by one degree, but did not know if either compass was correct! We had to bail out of the trip by building a raft and floating a fast moving but S-curving river for most of 2 days. Wondering if he could spot which curve we were at on day 2, he sighted on a known peak at about 25 degrees to the main axis of the river and, we both agreed, nailed it. Impressive, but we did not have to trust the results or our ability to replicate the results repeatedly. My compass could not have delivered the accuracy required -- and we did not know his could, so in an emergency and in the absence of a means of double checking, we could not have depended on his result.

Tired, cold, taking a bearing from an object too close and high to do well with the compass level, using a too-small compass -- any of these makes accurate reading difficult. So use your compass as though you know it is inaccurate. That is usually good enough and a lower risk strategy. It saves a lot of time, too.

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