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question on compass


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  • #1968619
    Jeremy and Angela
    BPL Member

    @requiem

    Locale: Northern California

    Orient your map to the magnetic north of the compass and then shoot your azimuth.

    If the map is not sufficiently recent, the map's idea of magnetic north will be different from the compass's idea of magnetic north, and you're back to making an adjustment.

    shoot two azimuths to recognizable landmarks and draw lines on your map using the edge of the compass

    And if you draw a third line, from a third point, chances are you have a small triangle rather than a point.

    I'd only assume a compass is accurate to about 1-2 degrees even if it has markings for additional precision. I believe the spec for the military ones is markings at 20 mils, with a max error of 40 mils (i.e. 2.25 degrees).

    #1968620
    Martin M. Clark
    BPL Member

    @martin_m_clark

    Locale: Southeast US

    I believe I'll be skipping the mirror and have decided based off several opinions on picking up the Suunto M3-Global Compass. I feel like this should be sufficient for my needs.

    THanks in advance to all who have contributed their knowledge.

    If this compass doesn't work out or I need a mirror, I'll just have to return it to REI : )

    #1968639
    BPLwiia
    Spectator

    @bplwiia

    I have two Silva Rangers and both have declination adjustments. I'm likely the minority but I never use that feature.

    Before I go out, I draw magnetic north lines on my maps. That way when I'm hiking I don't have to add or subtract the declination adjustment.

    There's no right, or wrong, only that which is more comfortable.

    #1968646
    Rob E
    Spectator

    @eatsleepfish

    Locale: Canada

    I used to only be interested in compasses with adjustable declinations, but now that I've used the declination scale on a few, it's quite easy, and I prefer it in some instances. For example it allows you to switch between magnetic and geographic bearings without mental gymnastics to ensure you've added (or subtracted) to remove the declination properly without getting the sign mixed up, you can cut the annoying lanyard without being worried about losing the adjustment tool (if applicable), and you don't need to worry about inadvertently changing the tool free declination, which happened to me once while doing a geoscience job, which was quite embarrassing.

    I'll be going to South America with the Suunto M3G in a few months, and I'm quite interested to see how it performs.

    #1968673
    David Thomas
    BPL Member

    @davidinkenai

    Locale: North Woods. Far North.

    >"I'll be going to South America with the Suunto M3G in a few months, and I'm quite interested to see how it performs."

    In Zimbabwe I found the N-S thing more confusing at times than driving on the wrong side or the million-Zim-dollar notes, etc.

    What, the sun is in the NORTH at noon? And the analog watch as a compass, I found trickier than I would have expected. after thousands of hiking hours with things being the other way around. . .

    #1968691
    Jim Colten
    BPL Member

    @jcolten

    Locale: MN

    In Zimbabwe I found the N-S thing more confusing at times than driving on the wrong side

    An acquaintance who moved to the US from Australia reported the same thing … could never get east/west right because the bleeping sun is the wrong place!

    #1968713
    peter vacco
    Member

    @fluffinreach-com

    Locale: no. california

    is a novice deal, but one can get dec of the day at yer location by setting most any garmin gps to the "magnetic" (as opposed to "true") option, and this will show you the local declination.
    i am not so totally sure how accurate the data is, but it beats to heck the numbers on an old map.

    cheers,
    v.

    #1968928
    Eric Blumensaadt
    BPL Member

    @danepacker

    Locale: Mojave Desert

    Nick, don't worry about compasses with declination. Any month now the poles will reverse and we'll all have to rely on our GPSs. (You DO have a GPS, right?)

    Yes, Nick, the magnetic apocalypse is coming. We will all get high doses of solar radiation due to the ionosphere thinning with this cataclysmic event.

    BUY A GPS AND SPF 100 SUNSCREEN!! BE PREPARED! (Jus' messin with ya Nick ;o)

    OTOH, if you are into orienteering and other precision wayfinding activities DO get a compass with declination adjustment. No more mental gymnastics, no more trying to erase old declination lines off your map. Just point and shoot that azimuth.

    But "seriousnessly", there IS a magnetic anomaly in the area of the South Atlantic near the Falklans Islands with a large magnetic NORTH area slowly drifting toward southern South America and about this I kid you not. Further it IS causing more solar radiation to hit the earth in that area. I don't understand the meterology about that but it's well documented.

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