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Thread: Compass Navigating 101

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    Anti-social Behavior DerBiermeister's Avatar
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    Exclamation Compass Navigating 101

    I worked this lessen up for another forum -- but it applies here too. (This first part is 101 -- basics of compass navigating. I will soon post 102 -- advanced navigating in conjunction with maps, etc.).

    If you are into prepping/surviving, the mechanical compass is a "must have" in your EDC bag or larger BOB. We are all used to having electronic gadgets that do our navigation today, whether it is a GPS, or Smart Phone compass, etc. But, in a SHTF event, the likelihood of losing power (via an EMP) and most forms of communications and transportation is high. If you are not trained in their use, you don't just pick up a compass and start navigating. Let's say you are fleeing your homestead for some safer location that is -- pick any distance (100 miles?) away. You've decided following road systems is too dangerous, so you set out across some wilderness. Having a good compass and knowing how to use it could make life a lot easier.


    LEARNING THE BASICS OF A COMPASS, AND HOW TO TAKE AZIMUTHS.

    I've decided to do this series on compasses and navigating in two, possibly three parts. The first part (101) will introduce the reader to the compass, its parts, and how to use it in the simplest ways -- but ways that could still keep you from getting lost. The next part (not here today) will go on to intermediate use, involving learning all about maps and charts and how to integrate their use with a compass.

    All mechanical compasses work using Magnetic North. There are two basic kinds of compasses – the first kind is known as the Orienteering Compass, ones with needles that always point to magnetic north. The second kind of magnetic compass – called a Magnetic Card Compass -- uses a magnetized compass dial (or card) with Compass Rose, instead of the magnetized needle.

    Orienteering Compass
    There are also two forms of the Orienteering Compass -- the Base Compass, and the Mirrored Compass. These are very similar except that the Mirrored compass allows for increased accuracy when actually shooting azimuths as you sight it like a rifle. Both versions can be used in conjunction with maps.

    example of an Orienteering (Mirrored) Compass
    Click image for larger version. 

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    Once you have an azimuth (target bearing) sighted in, you rotate the bezel (which houses the compass card with cardinal points) to exactly line up the orienting arrow on the card with the magnetic needle. Your azimuth bearing is now the number (in degrees) that lines up with your Sight Line (sometimes on base compasses referred to as Direction Of Travel line, or Index line).

    Study this diagram below before and learn the terminology of each part before moving on. Remember – with the Orienteering Compass, the needle stays fixed on Magnetic North and the card (with degree bearings, compass rose, and Orienting Arrow) moves (via a bezel) underneath it.

    (click on the image to enlarge it)
    Click image for larger version. 

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    The diagram below shows the Compass Rose. A compass rose is a circular figure on a compass, map, nautical chart or monument used to display the orientation of the cardinal directions—North, East, South and West—and their intermediate points. The one shown below expands it out to 16 points. Most compasses employ some form of the Compass Rose (4, 8, 16, or even 32 pts) on the card.

    Click image for larger version. 

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    Magnetic Card Compass
    Again, this type of compass uses a magnetized compass dial (or card) with Compass Rose, instead of the magnetized needle. Military forces of a few nations, notably the United States Army, continue to issue field compasses with this method. A magnetic card compass is usually equipped with an optical, lensatic, or prismatic sight, which allows the user to read the bearing or azimuth (0 to 360 degrees) off the compass card while simultaneously aligning the compass with the objective. One advantage of the magnetic card compass is that it takes one less step to obtain a bearing to the target, that being you do not have to move a bezel to align an orienting arrow with a needle. One disadvantage however (depending on your needs) is that the 0-360 bearing scale is resolute down to only 5 degree increments, instead of the 2 degree increments found on most Orienteering compasses.

    This thing is built like a tank! I have one and love the Tritium markings for night time use.
    Click image for larger version. 

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    Navigating Without Maps Or Charts
    This is not the best situation, but if you find yourself without maps or charts, but you DO have a compass, you can travel from one location to another in the wild as long as you know a general bearing with which to head for. Both styles of compasses have an easy way to do this. With the Magnetic Card compass, there is a movable (via bezel) Index Line that you can use to overlay on top of the North line, so that when you have your bearing to your destination, you simply keep the two lines on top of each other and walk in the direction of your Sight Line.
    Similarly, when using the Orienteering Compass, you keep the magnetic needle positioned directly over top of the Orienting arrow on the card while you walk in the direction of your Sight Line.


    (continued in next post)
    Last edited by DerBiermeister; 12-24-2014 at 09:57 PM.
    “Keep your scope up and we’ll shoot that SOB down the throat” -- Dudley "Mush" Morton, USS Wahoo
    "Hit hard, hit fast, hit often" -- Adm William "Bull" Halsey

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    Anti-social Behavior DerBiermeister's Avatar
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    (Compass Navigating 101 cont.)

    Declination
    Once you’ve become familiar with the parts of a compass, you then have to understand what “declination” is, before you can actually navigate with use of maps and charts.

    First off -- everyone should realize that all mechanical compasses utilize Magnetic North.

    The magnetic north is not close to the actual North Pole (which is True North on most all maps and charts). As you face the globe (with North America prominent), the magnetic north is to the left and lower than True North or the actual North Pole. Magnetic North also changes slightly every year.

    (click on the image to zoom in)
    http://www.almanac.com/sites/new.alm...rth%20Pole.png


    If you happen to live in America and somewhere close to the Mississippi River, your compass bearing is approximately the same for both Magnetic North and True North. So that is called Zero Declination. But if you live on either side and start moving away from that Longitude, the difference (expressed in degrees) between True North and Magnetic North starts increasing. If I am physically located West of the line of zero declination, a compass needle will give a magnetic reading that is east of true north. Conversely, if I am east of the line of zero declination, a the compass needle will point west of true north. These differences gain in significance the further away you are. The terminology gets kind of confusing as to whether you have EAST Declination or WEST Declination. So my advice is to first understand the concept, by looking at the chart below, whether you have to add or subtract degrees. For instance, here in Richmond VA, we are -10°W. As I am east of the Mississippi River, I know I have to SUBTRACT degrees from any azimuth reading I take with a magnetic compass. So once I am lined up with North, and I take an azimuth to some object, lets say it is 290°, my real azimuth, correcting to a True North, is 280°. I always need to stand there and visualize that my Magnetic North is WEST of my True North by 10°.

    BE ADVISED that the next two maps are "dated" and only approximate, and shown here just to demonstrate the declination effect. On these maps, the further out you get from 0 declination (in either direction), the more error in the maps there will be. As example: San Francisco appears on the first map to have a declination of 14+ degrees, when in actuality it is 13° 47' (which as you'll see later, you round up to 14°). This error is due to the age of the image shown. Some other maps found on the internet will have it at 15+ degrees because of the age of the map. To find your TRUE declination that is current, you need to do a calculation using the NOAA website below.
    (click on the image to zoom in)
    http://www.prepperforums.net/forum/a...inental_us.png

    Canadian Declination
    http://www.matematicaescuola.it/mate...ile/dchart.gif

    This declination becomes important when you try to navigate using maps or charts (which as I already said are always set up to True North). You have to make the declination correction. If you were to navigate (shooting azimuths) strictly by magnetic north and apply the results onto a map or chart, and you are trying to get from point A to point B (lets say 100 miles away), you would miss your target by many many miles if you don't do the declination conversion.

    You also need to know what that declination offset is in the area where you live. You can approximate this using any of the hundreds of declination charts that are available on the internet. To get more accurate, use one of two methods:

    1. Use current date topographical maps for the area you are going to be hiking.

    2. Use this site below from NOAA. First, on the right, you enter your zip code and at the bottom, click on GET LOCATION.

    The screen will now update filling in your long/lat info. You then click on CALCULATE, and your exact declination will be shown in degrees, minutes, and seconds. For correcting your compass, you only need to observe degrees and minutes. As 60 mins = 1 degree, you round up or down as the case may be. Example: San Francisco calculates out to 13° 47'. You would round up to 14° to correct your compass.

    http://www.ngdc.noaa.gov/geomag-web/#declination

    Also, good maps and charts will always provide the True North, and magnetic Declination information. It is important to have relatively current maps because of the degree change over years.


    Better yet, some of the better orienteering compasses (like a Suunto MC-2) have a mechanical adjustment to set the declination so that you no longer have to make this conversion when navigating with maps and charts. Making the adjustment actually permanently moves the compass card the correct number of degrees (either East or West) for whatever location you are in. Just remember, if you take your compass a significant distance away from your home base (example: you are in San Francisco, but decide you want to hike in Colorado - find out the new declination for your area in Colorado and then make the appropriate adjustment on your compass.)

    Now we are going to go through a series of videos that instruct how to use a compass in the field.

    This first video explains how to take simple azimuth readings to locate where you are. Dan (the instructor) is using a Mirror Sight version of the Orienteering Compass.
    http://atactv.com/mirror-sighting-compass-basics/

    In the next video, Dan demonstrates Dead Reckoning/Modified Resection using the military Lensatic compass. This works by knowing a particular trail or stream (on the map) and then shooting one azimuth to get a reciprocal bearing back to intersect with the trail on your map. You also get introduced to some basic stuff with Topo maps. Note that he has to add in his Declination since the Lensatic compass does NOT have a mechanical correction feature.
    http://atactv.com/position-fix-modified-resection/


    This next video is similar to the one above, except he shoots two azimuths to get two reciprocal bearings to triangulate a position on his map -- without having the advantage of a trail or stream. This method is called a Resection (meaning you take two azimuth readings).
    http://atactv.com/position-fix-resection/

    This concludes the 101 part of the instruction.
    Last edited by DerBiermeister; 12-24-2014 at 10:28 PM.
    “Keep your scope up and we’ll shoot that SOB down the throat” -- Dudley "Mush" Morton, USS Wahoo
    "Hit hard, hit fast, hit often" -- Adm William "Bull" Halsey

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    Great post, it's been a long time since I did any orienteering and I need to brush up on it. I guess one of these days I need to break down and replace my old Silva compass that went missing years ago.

    -Infidel
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    Definitely a perishable skill and never was a strong point of mine, thanks for the post

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    Dinky Dau Montana Rancher's Avatar
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    I agree great post, I learned my first lesson in land navigation hiking cross country with a backpack and a few friends in the 70's. Montana is simple as you have easy to see reference points, unlike the east where it is so flat you can't see anything. We used Topo maps but not much need for a compass as we just oriented the map to the terrain and it was simple.

    The army taught me to use a compass in places like Fort Sill OK where the tallest "hill" was about 400 feet high and so you couldn't use land reference.

    I still know my pace count, and have a military issue compass as shown above in my get home bag, but truthfully in Montana you don't really need one if you have a map.

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    Anti-social Behavior DerBiermeister's Avatar
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    Damn -- I just saw where my videos are no longer available to view. I am going to have to somehow find a fix for that.
    “Keep your scope up and we’ll shoot that SOB down the throat” -- Dudley "Mush" Morton, USS Wahoo
    "Hit hard, hit fast, hit often" -- Adm William "Bull" Halsey

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    Dinky Dau Montana Rancher's Avatar
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    Quote Originally Posted by DerBiermeister View Post
    Damn -- I just saw where my videos are no longer available to view. I am going to have to somehow find a fix for that.
    The site has upload parameters that are very draconian, more that likely the link is too large. I try to post recent pictures and I usually have to shrink them a LOT to get them to upload.

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    Anti-social Behavior DerBiermeister's Avatar
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    Quote Originally Posted by Montana Rancher View Post
    The site has upload parameters that are very draconian, more that likely the link is too large. I try to post recent pictures and I usually have to shrink them a LOT to get them to upload.
    No this is something from the source site -- where they have yanked the videos. Notice the "This video is unavailable" message when clicking on it. The videos worked fine here for a long time until just recently.

    I've seen this before on other stuff.
    Last edited by DerBiermeister; 02-26-2015 at 07:34 AM.
    “Keep your scope up and we’ll shoot that SOB down the throat” -- Dudley "Mush" Morton, USS Wahoo
    "Hit hard, hit fast, hit often" -- Adm William "Bull" Halsey

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    ədˈminəˌstrātər hawgrider's Avatar
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    Five Map and Compass Skills Every Outdoorsman Should Master

    "The clever cat eats cheese and breathes down rat holes with baited breath." W. C. Fields

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    I taught Land Nav in most of the units I was in during my 21 years it is a perishable skill and too many kids today don't think they need it, they have smart phones and GPS. I teach all my nieces and nephews when I teach them about hunting and fishing. I also taught it to a bunch of third graders this year when I had to do a classroom visit for one of my college classes they actually paid attention even if they did not fully grasp everything. I know many of them through sports teams my nieces play on and have had some asked me to teach them more this summer during camping trips when all the families are out on them.

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