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convert coordinates on a property survey to a compass direction

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  • convert coordinates on a property survey to a compass direction

    Hello all,

    I have a property survey that has in the following format S89degrees 17' 49"W on two points on the survey...how do I convert to a compass heading? or is the 89 degrees the proper compass heading?

  • #2
    Re: convert coordinates on a property survey to a compass direction

    Originally posted by Unregistered View Post
    Hello all,

    I have a property survey that has in the following format S89degrees 17' 49"W on two points on the survey...how do I convert to a compass heading? or is the 89 degrees the proper compass heading?
    Surveyors use quadrantal angles 0-90 east or west of due north or due south. The meaning is 8917'49" west of south. 90 west of south IS west, so almost due west.

    Navigators measure bearings 0 - 360, where 0 (or 360) is north, 90 east, 180 south, 270 west. For the SW quadrant, add the quadrantal angle to 180, ie 26917'49", very slightly south of due west.

    For all quadrants, to convert quadrantal angle to true bearing:
    NE: Use angle as is
    SE: Subtract angle from 180
    SW: Add angle to 180
    NW: Subtract angle from 360

    For an actual compass bearing, note that a compass points at the north magnetic pole, not the true north pole (earth axis). The correction for that may be a few degrees and depends on your location. It is sometimes printed on local maps and is called variation or magnetic variation.

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    • #3
      Re: convert coordinates on a property survey to a compass direction

      Thanks for making this site available. It makes problems seem much easier to understand!

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      • #4
        Re: convert coordinates from a surveyor's bearing to a compass bearing

        Pls convert the following coordinates from a surveyor's bearing to a compass bearing
        They are 005 degree, 075 degrees, 156 degrees, 231 degrees and finally 320 degrees
        I'll be very grateful to get the answers as soon as possible

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        • #5
          Re: convert coordinates from a surveyor's bearing to a compass bearing

          Originally posted by Unregistered View Post
          Pls convert the following coordinates from a surveyor's bearing to a compass bearing
          They are 005 degree, 075 degrees, 156 degrees, 231 degrees and finally 320 degrees
          I'll be very grateful to get the answers as soon as possible
          I am not sure what you are asking. Those are, or could be, compass bearings. Surveyors usually use true north as a reference, compass, magnetic north, so you have to know local variation.

          North is both 0 and 360, east, 90, south, 180, west, 270.

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          • #6
            Re: convert coordinates on a property survey to a compass direction

            "Surveyors usually use true north as a reference, compass, magnetic north, so you have to know local variation."

            Other variables exist. First, in addition to true and magnetic north, a survey may also utilize State Plane Coordinates which yields 'grid north' or many surveys utilize an 'assumed north'.
            If indeed the surveyors bearing is a true bearing you would need to know your approximate latitude and longitude so you could find the declination using an on-line tool such as NOAA National Geophysical Data Center Magnetic Field Calculator on-line tool (sorry, site won't let me post link)
            If the surveyors bear was already a magnetic bearing you would need to know your latitude and longitude, the year it was surveyed so you could find the declination for that year and the declination for the present date and then determine the difference.
            If the surveyors bearing is grid, you could approximate the true bearing using the National Geodetic Survey Geodetic Tool Kit State Plane Coordinate on-line tool (sorry, this site won't let me post link) by adding or subtracting (as appropriate) the convergence angle and then prceeding as above with the instuction for a true bearing.
            Lastly, if the survey is on an assumed bearing you could use your compass the determing the bearing of a known line and then apply the difference between the survey bearing and your observation to the other lines of the survey.
            I know this responds to an old post and there is not enough room to answer in greater detail, but I hope this helps!

            Land Surveyor

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            • #7
              Re: convert coordinates on a property survey to a compass direction

              What would be the way if you are running a line back to the starting point. say the call is from a point south 66 deg 48 min 00 secs west and you are at the ending point for this call. The line runs about one mile though heavy brush. I know the ending point need to find the beginning with my compass. That is a long walk to get to the beginning of call. I think it is compass heading of 112deg 12min 00 sec. Is this right????? I need all the help I can get. Thanks

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              • #8
                Re: convert coordinates on a property survey to a compass direction

                Originally posted by Unregistered View Post
                What would be the way if you are running a line back to the starting point. say the call is from a point south 66 deg 48 min 00 secs west and you are at the ending point for this call. The line runs about one mile though heavy brush. I know the ending point need to find the beginning with my compass. That is a long walk to get to the beginning of call. I think it is compass heading of 112deg 12min 00 sec. Is this right????? I need all the help I can get. Thanks
                Note the explanation of quadrantal angles in post #2. To reverse a line 180, change BOTH letters. The reverse line is N 6648'00" E or 066.8 (true). Note that a compass points to magnetic north. You need to determine local variation (angle between true and magnetic north) for your location. Note that a 1 degree error will lead to about a 92 foot crosstrack error at a distance of 1 mile.

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                • #9
                  Re: convert coordinates on a property survey to a compass direction

                  Thanks John,
                  change letters! 180 change! could have had a v-eight. You saved my day and my brain. Sometimes some of us do complicate things????

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                  • #10
                    Re: convert coordinates on a property survey to a compass direction

                    Originally posted by Unregistered View Post
                    Thanks John,
                    change letters! 180 change! could have had a v-eight. You saved my day and my brain. Sometimes some of us do complicate things????
                    As an amateur sailor and navigator, I much prefer 0-360 bearings. However, that is one advantage to surveyor's quadrantal angles. To convert between the two, there are four separate rules (in post #2).

                    I have absolutely done in the hard way before thinking it through and seeing it was trivial. In traverse calculations to determine area, it is necessary to recognize every line points two ways, and the direction the surveyor shot is not always the direction you are traversing; reversal is used frequently.

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