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Thread: Tater or other Surveyor...

  1. #1
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    Default Tater or other Surveyor...

    Trying to locate a property line using a compass or GPS. I know where all the pins are but lines are long and line of sight is currently not possible.

    I know not super accurate but...

    If this is my line from my survey :


    Am I correct in converting it to a Azimuth Bearing of approximately 86* but with my local declination approximately 93* and if I am walking the line the other way 266* or 273* with declination?





    If that is correct then because of declination I would actually set my bearing to 93* or 273* depending on which way Iím walking correct?

    Thanks for any info or help!




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    Last edited by Johnny Reb; 08-18-2019 at 03:33 PM.

  2. #2
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    In theory, yes. In practical application? Probably not.

    The ref bearing used for the plat is what you need to know.

  3. #3
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    I would mark the pins with a handheld gps and then hit go to. Walk the line. Need to zoom way in doing this.

  4. #4
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    But, since you know where the pins are you can drop a waypoint on each. Set a track from one to the other and follow the bearing on your compass.

    You wonít be dead nuts, but youíll be close. I would say worst case you are 60í off and will most likely be within 30í at any given point.

  5. #5
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    Default Tater or other Surveyor...

    Quote Originally Posted by Tater View Post
    In theory, yes. In practical application? Probably not.

    The ref bearing used for the plat is what you need to know.
    This?



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    Last edited by Johnny Reb; 08-18-2019 at 05:35 PM.

  6. #6
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    Look at the north arrow on the plat. It should say Grid or SCSPCS Grid. If it does then donít worry about declination, just roll with your iPhone or GPS bearing.

  7. #7
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    Quote Originally Posted by Bad Habit View Post
    I would mark the pins with a handheld gps and then hit go to. Walk the line. Need to zoom way in doing this.
    Quote Originally Posted by Tater View Post
    But, since you know where the pins are you can drop a waypoint on each. Set a track from one to the other and follow the bearing on your compass.

    You wonít be dead nuts, but youíll be close. I would say worst case you are 60í off and will most likely be within 30í at any given point.


    Thatís what I planned to do to check my line from original thought above. Guess I will just go that route.

    When you say 30 to 60 off you are talking feet to one side or another?




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  8. #8
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  9. #9
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    Your azimuth will be 79 degrees if following the plat direction or the reverse will be 259. Those numbers are already taking in the declination. The declination is -7 so you will always subtract it from an azimuth. The plat bearings run clockwise from the sc grid tie point. Which is the point the coordinates is on.

    Therefore 86-7= 79. Because it is in the NE quadrant the azimuth is the same as the bearing.
    Last edited by banded_mallard; 08-18-2019 at 05:36 PM.

  10. #10
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    State Plane grid north doesnít give a damn about declination and never changes with declination.....

    If anything, youíre thinking about convergence, which is the angle between grid north and the central meridian, 81W in SC for those keeping score at home, and and most will be measured in seconds, not degrees.

    Treat the bearing as true and rock on.

  11. #11
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    Surveyor talk is Rad...

  12. #12
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    Quote Originally Posted by Steelin' Ducks View Post
    Surveyor talk is Rad...
    Yes it is.

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  13. #13
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    Quote Originally Posted by Steelin' Ducks View Post
    Surveyor talk is Rad...
    I see what you did there...

  14. #14
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    Quote Originally Posted by Tater View Post
    State Plane grid north doesn’t give a damn about declination and never changes with declination.....

    If anything, you’re thinking about convergence, which is the angle between grid north and the central meridian, 81W in SC for those keeping score at home, and and most will be measured in seconds, not degrees.

    Treat the bearing as true and rock on.
    I will preface this with that in this case we are splitting hairs. However Tater, correct me if I am wrong, but State plane is very close to true north. A compass that does not do declination is reading magnetic north which would put you off 7į. If you had a compass with a declination of -7į then yes you could read it right off the plat.

  15. #15
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    Compass yes, but not the iPhone or GPS that I told him to use. They both run on true north. Grid north is equal to true north only along the central meridian, which is 81W In SC. Heís in Lexington county and Lexington the town is at 81.2362W.

    Even at the far eastern and western longitudes in SC the convergence angle is minuscule.

    Thatís why I told him to use his phone or GPS.

  16. #16
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    Thanks for the help Tater and Banded Mallard. I appreciate it!


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  17. #17
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    Quote Originally Posted by Steelin' Ducks View Post
    Surveyor talk is Rad...
    AND TATER is the MAN. He really is the best I ever seen. I seen his work with the help of TaterTot.
    Gettin old is for pussies! AND MY NEW TRUE people say like Capt. Tom >>>>>>>>>/
    "Wow, often imitated but never duplicated. No one can do it like the master. My hat is off to you DRDUCK!"

  18. #18
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    Quote Originally Posted by banded_mallard View Post
    Just FYI the iPhone compass only reads true north if you turn that on in the settings. Tater and I are in agreement on this though.

  19. #19
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    Mousetrap?

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