True North or Magnetic North?

[ODB]

They do, but declination also shifts over time so it's often out of date. There are websites with the current values like https://www.ngdc.noaa.gov/geomag/calculators/magcalc.shtml and https://www.magnetic-declination.com/
According to them, Campbell, KY is now 6.6 degrees west.

I like trying to be accurate, but I don't think a few degrees has ever made a difference for my use.

This is a good reminder. I once tried to map out a piece of property using an old land plat from the 20s or so. I did the work on Illustrator drawing out the rods and chains/ bearing etc, but it didn’t overlay on my satellite map like I expected because one border of the property was a known road and it just didn’t fit. . I remembered that declination changed over time, went back and checked what the declination was 100 years ago and reset my boundaries.perfect. It was like a puzzle piece clicking into place. Very satisfying.

 

[dutch_henry]

This is a good reminder. I once tried to map out a piece of property using an old land plat from the 20s or so. I did the work on Illustrator drawing out the rods and chains/ bearing etc, but it didn’t overlay on my satellite map like I expected because one border of the property was a known road and it just didn’t fit. . I remembered that declination changed over time, went back and checked what the declination was 100 years ago and reset my boundaries.perfect. It was like a puzzle piece clicking into place. Very satisfying.

That is super cool. Love hearing stories like this.

 

[nodakian]

This is what my surveyor friend suggested, and what I'll do.


[True or Magnetic] It will probably matter but I'm not sure which is best, probably true north. I recommend you run a random line and correct back like the surveyors did in the old days.

What you do is choose a north heading and keep pushing that line as perfectly straight as you can marking it with flagging as you go. It doesn't matter if you hit the second corner with your line, you just want to push the line as straight as possible. It will help if you pull a 100' tape measure or shoot the distance to each piece of flagging with a rangefinder and write the total distance traveled on each piece of flagging with a sharpie.

Then when you get to the other corner, the line you pushed will miss that corner on one side or the other. So let's say for example you measured 2600' and the line you pushed ended up 30' west of the second corner. So then you know that the straight line you pushed and flagged was deviating to the west of the true line. So now you can go back and move all the flagging the proportionate amount to the east to be approximately on the true line. That's why writing the distance on the flagging helps because you can figure out the proportion. It's just a straight proportion 30/2600 = x/distance measured. With x being the correction offset. So let's say for example you have flagging at 425' up the line, cross multiply and divide to determine the offset: 30/2600 = x/425. x = 4.9 feet.

In ideal world--one with fewer lawyers and annoying neighbors --this would work fine. However, reality being what it is, what's the chance your surveyor would stake the line with modern equipment for a respectable quantity of his favorite adult beverage? We surveyors can often be persuaded to work as long as we're not thirsty.

Good luck with your project.

 

[Q child]

When using a real compass I use true north.

 

[littlerhorner]

A humble word of caution. I think it is cool that you have taken the time to understand the theory and application of proportion to find the true line. That is what the "old timers" did and in all fairness they did it pretty dang well.

In the case of the general land office and later the BLM they were in fact using the best avaible tech to do there job. They also were using 3-5 mam crews. This is important because the instrument man was using a theodolit or transit to keep a rod man on a straight line.

Probably the most important difference though is that the US government owned both sides of the line. That is important because they could not infringe on a neighbors property rights because they owned both sides of the line. In your case you only own one side. The other difference is they were preforming and original survey. That means that the monuments they set are viewed to be without error. You are retracing a survey. There is an established line. You will not be afforded the same notion of without error. I think you would do well to look at a few of those surveys and see just how much they missed the north quarter section monument in one mile using the techniques you are proposing.

To my knowledge, in the areas I work, there is nothing to stop you from doing what you propose, but you should also aquiant yourself with the state statues regarding fence law, adverse possession, and tresspass.

I am not trying to stop you, just putting this out there for anyone who may dig this thread up later so that they can have some resources to look into further if they choose.

 

[couesbitten]

I'm just going to follow her lead.

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[Pharmseller]

Error east, compass least.



P

 

[RockAndSage]

Not so much about your property surveying, but given that you brought up the subject of magnetic vs. true north, there are some things related to the shifts in magnetic north that are probably worth bringing up here...

Magnetic north has started shifting pretty rapidly in the last 20 years - it's not as stable as it used to be. Historically it's been moving away from Canada and toward Siberia at about 5 miles per year, but for the last 20ish it's been moving at around 30 per year. Presently it's about 1,300 miles off where it was two hundred years ago, and is still moving away. It's a pretty good idea to know how to find true north day or night, and keep up to date on being able to adjust for declination in your area.

Something that may be related that can also affect our backcountry navigation, is that there's some pretty good evidence that our planet's magnetosphere, which blocks out a lot of the electromagnetic radiation coming out of the sun, is weakening - it's lost about 10% of its strength in the last century or so, and it's increased that rate of weakening for the last 15. About half of this loss in strength has occurred during this recent period. Weaker magnetosphere means more electromagnetic energy penetrating deeper toward the planet's surface, causing more damage to satellites and possibly other electronic equipment than it could have just 20 years ago. Elon Musk lost a bunch of satellites a few months back from a solar storm that shouldn't have caused that much damage, likely because of the differences in magnetosphere strength between what existed and what was engineered for.

Add to this that the sun's on an upswing in one or more of its cycles, and it's increasingly pumping out solar storms and coronal mass ejections - a couple of weeks back it ripped out a solar flare at least as big as the Carrington Event one in the 1800s that fried the world's infant telegraph systems, to the point where it was lighting some of it on fire. We got lucky in that this recent one was pointing almost exactly opposite of Earth, but had it hit us there's a good chance the sun-facing side of the planet would have had its electrical grid go down, along with most of the planet's orbiting satellites.

While I rely on GPS and OnX in the back country, I also try to find the best paper maps I can of an area as backup, but it's increasingly difficult to find them. Anyone have any good sources?

 

[PurpleDriver]

I prefer magnetic so that the app will match my wet compass if I have to fall back to the old school compass.

 

[Coveyleader]

I prefer magnetic so that the app will match my wet compass if I have to fall back to the old school compass.

FYI……. GPS is based off True, mapping program most likely grid, so it’s not going to match a “compass”

 

[littlerhorner]

Not so much about your property surveying, but given that you brought up the subject of magnetic vs. true north, there are some things related to the shifts in magnetic north that are probably worth bringing up here...

Magnetic north has started shifting pretty rapidly in the last 20 years - it's not as stable as it used to be. Historically it's been moving away from Canada and toward Siberia at about 5 miles per year, but for the last 20ish it's been moving at around 30 per year. Presently it's about 1,300 miles off where it was two hundred years ago, and is still moving away. It's a pretty good idea to know how to find true north day or night, and keep up to date on being able to adjust for declination in your area.

Something that may be related that can also affect our backcountry navigation, is that there's some pretty good evidence that our planet's magnetosphere, which blocks out a lot of the electromagnetic radiation coming out of the sun, is weakening - it's lost about 10% of its strength in the last century or so, and it's increased that rate of weakening for the last 15. About half of this loss in strength has occurred during this recent period. Weaker magnetosphere means more electromagnetic energy penetrating deeper toward the planet's surface, causing more damage to satellites and possibly other electronic equipment than it could have just 20 years ago. Elon Musk lost a bunch of satellites a few months back from a solar storm that shouldn't have caused that much damage, likely because of the differences in magnetosphere strength between what existed and what was engineered for.

Add to this that the sun's on an upswing in one or more of its cycles, and it's increasingly pumping out solar storms and coronal mass ejections - a couple of weeks back it ripped out a solar flare at least as big as the Carrington Event one in the 1800s that fried the world's infant telegraph systems, to the point where it was lighting some of it on fire. We got lucky in that this recent one was pointing almost exactly opposite of Earth, but had it hit us there's a good chance the sun-facing side of the planet would have had its electrical grid go down, along with most of the planet's orbiting satellites.

While I rely on GPS and OnX in the back country, I also try to find the best paper maps I can of an area as backup, but it's increasingly difficult to find them. Anyone have any good sources?

The USGS has the standard 1:24000 quad maps to download load or order. It is a great resource.

 

[PurpleDriver]

FYI……. GPS is based off True, mapping program most likely grid, so it’s not going to match a “compass”

Good point. I never thought about the mapping program being grid…and I can’t find a definitive answer for OnX.

I do know for a GPS, the satellites are giving signal in true, but you can typically set declination, so I don’t think I’d assume GPS is set to True. For me personally, my career uses magnetic headings via GPS, so setting up my handheld to mimic that makes sense to me. You are correct that it may not work for everyone.

This link is pretty good with some suggested setups and their advantages from GPS-Map-compass.

North References for Navigating with Map, Compass and GPS

MapTools - Tools and instructions for GPS users to work with UTM, MGRS and lat/lon coordinate systems.

www.maptools.com