Military Gear & Army Surplus Gear Blog

Using An Altimeter To Help You Navigate.

Using An Altimeter To Help You Navigate.


Bearings combined with pacing and timing
can be an absolute killer combination when it comes to navigating, but pacing
and timing and not infallible they rely on us as human beings remembering to
start and stop the stopwatch they remember as human beings being accurate
without pacing they’re not infallible and in fact even when we’re trying to be
mega accurate sometimes the ground that we are covering the ground that we are
on the terrain we are moving over means that pacing and timing are almost
worthless because our pace and timing can be so staggered and so slow there is
something else that you can use though combined with all of those that can help
to refine and pinpoint accuracy of where you are not everybody is able to use one
of these but if you’ve got one it can be an absolutely deadly thing to use you
want a clue I’m wearing it on my wrist hi folks I’m Craig Taylor and as always
a huge thanks for joining me here on my youtube channel the Bush matter one now
when I say and wearing on my wrist your natural assumption is that I’m talking
about a watch and indeed I am this is a son so cor watch but it has a feature
within this that makes it more than just a watch the feature is specifically that
I’m talking about and referring to in this video is an altimeter now before we
go any further in this video let me explain to those of you that haven’t got
a clue what an altimeter is maybe you’ve heard of it but you’ve never really
bothered finding out more about it what is an altimeter and that signature is a
tool doesn’t have to be in a watch I should add at this point but an
altimeter is a tool that allows you or tells you
your altitude your elevation the height that you are at let me explain
incredibly briefly one because I’m not a meteorologist or a scientist or anything
like that and so it’s the way that I best understand how altimeters work
let’s assume that my fist here is where I
in terms of height that the height the elevation is Allah is irrelevant there
is so much air above me air has a pressure so there is so much air
pressure above me if I move my fist down here if I lower my elevation there is
this much air pressure above me the higher I get still there the less air
the less air pressure there is above make the lower the air pressure the
lower I get the more the air pressure increases the greater the air pressure
the lower I get still the greater the amount of air the greater the amount of
air pressure the greater the amount of air pressure that is above me so it all
relates to the height that I am therefore it increases the air pressure
or it decreases the air pressure the higher I get the lower the air pressure
the lower I get the higher the air pressure now there were some caveats
involved with this that I won’t go into here but they go into the detail of
whether I’m ascending or descending incredibly quickly it’s down to the
accuracy of your altimeter weather conditions can play a huge role as well
but broadly speaking very broadly speaking if you’re a scientist if you’re
a mesh scientist please don’t rip me apart but broadly speaking that is how
an altimeter works so why should we be interested in our altitude why should we
be interested in tapping into what an altimeter can bring us well if you use
the sort of maps that I use which is a good quality topographical maps that
indicate your height using a range of things contour lines contour markings
spot Heights trig points things like that if you can be told by a tool
relatively accurately what your altitude is what your height is and you’re using
a map that is accurate in terms of the way that it displays altitude and height
there’s quite obviously a connection here that I can then take what this tool
is telling me relatively accurately we’ll come on to that in a second and
transfer that the month it basically fills the gaps in
in terms of what my altitude is you can determine your altitude without using an
altimeter but it’s far more rough-and-ready in my experience it’s
far more open to human error and prone to miscalculations and it’s just not as
quick to do to be perfectly honest now there are a couple of really important
factors to consider in my experience when using an altimeter the first one is
you’ve got to give it a fighting chance you can’t just expect to take this out
the box put it on your wrist and for it so to accurately know where you are and
your altitude and all the rest you need to give it a fighting chance
the way that I always give my altimeter a fighting chance at the beginning of
the day is to figure out what my start point is maybe it’s my house which is
just a mile or two that way I know from looking at the map that my house sits on
top of the 55 meter contour line so I know that when I’m stood downstairs in
my house I am standing at 55 meters altitude it’s a known point my house
isn’t rising my house I hope isn’t falling it’s a fixed point it’s unknown
points according to the map so I can then plug in so my altimeter 55 meters I
can set it or reset it to 55 meters I now know that all things being equal
talking about the caveats I mentioned earlier on that that has now been set as
a baseline it is being set at a benchmark of 55 meters I’ve given myself
a good starting point maybe I’m not starting from my house maybe I’m
starting from a track junction somewhere maybe I’ve spent the night at a campsite
maybe I’m staying in a youth hostel maybe I’ve just pulled up a car park at
the side of the road find out what that altitude is by careful inspection of
your map and the contour lines that’s fixed that’s known plug that into your
altimeter at the start of the day give your altimeter a fighting chance of
helping you out by being accurate once you’ve given your altimeter a fighting
chance at the start of the day keep giving it fighting
chances keep updating your altimeter as the day progresses when you are in a
known and fixed point therefore you can determine unknown and fixed
altitude what do I mean by this well I’m going to draw your attention to a map
and I’ll show you a few features on a map but I would use over a typical route
to help me keep my altimeter updated let’s look at this point that the map
vendor I’ve circled an initial SP for starting point
it’s a prominent road and it’s a track junctional forms across the track forms
of crossroads with a prominent road and by looking at the console lines I know
that that is at 230 meters so if that’s my starting point if that’s where I’ve
pulled my care over at the start of the day I know as long as I’m accurate in
where I’ll actually pull my kariv I’ve not pulled it over a different Junction
as long as I can confirm I’m at that Junction I should set my altimeter to
230 to 3 0 meters I’ve given it a fighting chance I then start on my
navigational route and I’m following all the normal principles and practices that
I should be doing when I’m navigating over a period of time I’ve made my way
up to this truck T Junction that’s at between these two sat in the middle of
this saddle between spot height 3 1 8 and 310 I’m starting that subtle in the
middle I mean if I look very closely at the contour lines that track Junction is
as near as damn 290 or 2 9 0 meters I can look down now at my altimeter if
that’s reading 290 meters I’m really happy I’m good to go if it’s reading
slightly either way I need to consider whether the inaccuracy that he’s telling
me is important or not I’ll come on to that in a second if it’s way off
I can then reset my altimeter to two nine zero meters and set off again now
when I said just a second ago whether the the inaccuracy I can live with it
whether it’s a big deal what I mean by that is if you look at the contours of
your map my contouring civil on this map is 10
meters on other maps that I use it’s 5 meters so if this is giving me an
inaccuracy of maybe one or two maybe three meters do I need to worry about
that the contour interval on this map is 10 meters so I’m always going to have to
some degree and an element of inaccuracy because it can only be accurate to 10
meters just two or three meters matter if I’m on an Ordnance Survey one in
25000 map and that the maps sheet that I’m using has a 5 meter contour interval
does a 2 or 3 matter a 2 or 3 area or my altimeter really matter personally I
think in the big scheme of things it probably doesn’t but I’m always mindful
of a small error on top of a small area on top of a small area error can add up
quite quickly so whenever whenever I am at a known point even if it’s only 1 or
2 meters out I will reset the altimeter to be exactly
in line with the altitude that the map is showing me when I reach this y-shaped
track junction here perhaps I now decide to take a bearing upon to create Garten
3 5 9 maybe I’m just going to take a direct bearing from that track Junction
up there and I’m just gonna use pacing and I’m going to use timing in
conjunction with my bearing to get me towards the top of that peak now as I
said earlier on bearings coupled with pacing and timing can be an absolute
killer combination but it may well be that as I’m moving up this this feature
at the side of this hill it does no harm at all as my height is increasing and it
will increase quite quickly going up that slope it does mean no harm at all
to be able to look down at my watch and realize that I’ve now moved up to the
300 meter contour line or I’m now saying that my ultimate is saying I’m at 306
meters I’m at 310 meters I’m at 3 1 7 meters you can start to get an idea now
I hope that if your watch your altimeter is giving you a cura or pretty damn
information is to your altitude if you’re now looking at the map and you’re
making your way up that slope you can start to get a sense for where you are
on that slope how far you’ve covered and how far you still have to go in order to
be able to get to the top yes pacing bearings and timings will all
help you gather that information it will all help you to determine that but it
for me it does no harm whatsoever to have those some what’s fallible options
also backed up by the altimeter that I’m naturally wearing anyway because it’s my
watch it’s part of my ADC my everyday carry it’s not extra equipment to carry
it’s not something else to buy once you’ve already bought the watch it’s
already inherently built into the kit I’m carrying some personally I think it
does know hammer or if you’re wearing or a considering buying or watching the
future and you can afford a watch that has an altimeter on it and you’re
serious about your navigation for me it’s almost personally a no-brainer to
consider getting an altimeter in your watch and finding out how and when and
where you can use it accurately there are loads of altimeter
out there some are built into watches some are standalone many are now just
inherently part of GPS and sat-nav systems but for me the sat-nav system is
something extra to buy it’s not something that I would wear day in day
out whereas I watch which is now showing at an altitude of 79 meters you can see
it’s something that I wear day in day out I’m never without it which for me
gives me more opportunities to practice use it I took a group out the other day
just a few miles from here a group of friends took them out for days
navigating and it just it just made me realize it’s something that I almost use
without realizing it it’s not it’s not something I’m overtly conscious of I’m
conscious when I take a bearing I’m conscious when I pace I’m conscious when
I set my watch and and and time a certain distance all of the traditional
navigational things for me I’m conscious of doing them but I must admit it’s
become almost second nature to me when I get to a known point I can see
I just reset my altimeter and it is a huge hugely beneficial and confidence
boosting backup to have in your back pocket but remember those two things I
mentioned give it a fighting start at the start of the day and keep giving it
a fighting chance whenever you are at a one punch a percent identifiable point
not what you think you are that where you absolutely know you are
once you’re there determine the altitude check your watch reset it and tweak the
adjustment if necessary because they can be affected by things like steep ascents
descents and significant changes in the weather thanks as always for watching
folks hopefully this has given you something to think about if you’re
thinking about buying an altimeter maybe this has helped to push you over the
line if you’re not for you think about buying a new watch and outdoorsy type
watch maybe it’s giving you something to think about and if you’re not thinking
about an altimeter maybe it’s just pressed home the importance of
recognizing and being able to determine your altitude your height and just how
important their terms that can be thank you as always for watching folks coming
up on the screen right now are a couple of my more recent navigation videos that
I have recorded why not check those out and I look forward to seeing you my next
video very very soon thanks Cheers


Reader Comments

  1. Hi Craig,

    Interesting topic.

    Please don't take this the wrong way- I completely understand where you are coming from, BUT, although it doesn't rely on satellites (your watch is reading air pressure and temperature as opposed to GPS altitude) it still relies heavily on electronics. if I wanted to put my location in the hands of electronics I would just use a handheld GPS. I agree if you are buying a new watch, extra info never hurts so by all means get an altimeter (or GPS) built in if you think you might need it some day.

    That said, I HAVE actually used altimeters to navigate and they have been very useful in very specific instances (usually navigating in low visibility like a snowstorm or heavy fog). Most of the time if I have an altimeter in the field though I use it for weather prediction.

    As a fun side note, I use the exact same methodology all the time on my sailboat to navigate. Using sonar allows you to follow bottom contours and cross reference a single bearing with an altitude (or depth contour in this case). It is exactly the same as navigating with an altimeter but flipped upside down! 🙂

    Anyways, thank you as always for making me think! Keep up the great work!

  2. Thanks for this thorough walk trough of the basics of the altimeter. A selling point (and idea for the next video 🙂 ) is how it makes contour lines on the map just as easy to find as natural lines in the terrain. "Walk uphill, aiming off a bit to the south up to 530 meters. Then turn and follow this hight (contour line) to the north." To use the altimeter this way, you of course it must of course be properly adjusted, as you already pointed out.

  3. Hi Craig! Interesting as always. I personally don't have an altimeter on my watch, but if I will ever get one I know (now) how to use it. Thanks to the master of navigation and have a nice weekend! André

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