Do I really need to know declination??

Discussion in 'Garmin GPS' started by lisach, Sep 23, 2023.

  1. lisach

    lisach

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    Hi Guys... I'm a complete newb. So Newb, I'm not even sure I'm in the right place to ask these questions. I have a large piece of rural remote mountainous wilderness property. (it's out there) I have a Garmin GPS device. I've been experimenting with the device on the property with waypoints and tracks and stuff. I need to walk the boundaries to mark the trees and locate survey markers. I have a really good survey that was done 23 years ago in 2000, and I have located the very beginning point from the survey. But from there it give 35 calls using bearings and distances. I thought if I could stand on the beginning point and mark the waypoint on my GPS device that I could then convert the 35 bearings and distances to GPS points which I could put into my device and create a route that I could use to walk the boundaries, mark the trees and locate the rebars that were set back then also. I've figured out how to put in the GPS coordinates to the device but then I've ground to a halting STOP.

    How do I convert these survey calls to GPS coordinates? I've found a couple of calculators but most of them use miles/KM. I'm dealing with feet and I do think that using a smaller fraction of miles will eventually be really off over 35 calls. It's not like someone's been breaking a rod on a lawnmower hitting these rebars over the years.

    And.... then... the survey has a declination note for a location and date of Dec 2000. 1st.... do I really need to know this? And how do I use this? Do I reverse calculate today's GPS point to what it would have been back then, convert the bearings and distances to what they would have been back then, then convert everything to what it is today? Will it really make a difference? OMG it makes my head spin....

    So.... is declination from 23 years ago really that important? What is a really quick and time-saving way to convert bearings and distances from a known starting point to GPS coordinates? Surely someone really smart has created a spreadsheet for this somewhere. (prayerfully, hopefully).

    Appreciate in advance advice from people who understand this better than I do.
     
    lisach, Sep 23, 2023
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  2. lisach

    Nuvi-Nebie Moderator

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    The projection of these Waypoints are best created in Garmin Basecamp, first you need to setup Basecamp to use Magnetic (rather than real) North, you can also enter your East / West offset for 23 years ago here using Edit >> Options >> Measurments >> Use Magnetic Variation, I have set it to West 10 Degrees eg :-

    proj-1.jpg

    Then Create your First Waypoint (001) by entering its co-ordinates, zoom into this Waypoint as much as possible on the screen, select the measurement tool and click on the Waypoint 001, while holding the left mouse button move the cursor to a new location, say 197 feet away at an angle of 100 Degrees, mark this location on screen (using a sticky paper marker), then select New Waypoint and create a new Waypoint say 002 at this new location, you can then repeat this process to project the remaining Waypoints

    proj-2.jpg
     
    Nuvi-Nebie, Sep 24, 2023
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  3. lisach

    lisach

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    I'm so thankful for your response. I have Basecamp and spoke with Garmin support about using it but with no solution. I'm on the mountain the next couple of days and will will dig deeper into your response when I return. Please hold on.
     
    lisach, Sep 24, 2023
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