HEY ALL YOU SCIENCE GEEKS!..

[knot smart]

I just read another interesting article about the magnetic poles shifting 50km a year. It got me thinking about navigation the old fashion way with charts. Obviously, with GPS chartplotters, probably no one navigates with a chart. However, one would assume that NOAA (or whoever) would have to annually update their charts to compensate for the adjustment. Can anyone confirm this?

Anyway, I thought it was interesting..



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[Tillsbury]

I’m going to hope you’re trolling. Yes, paper charts are regularly updated and magnetic variation noted at each rose. They also tell you how much it’s changing by per year. Are you seriously telling us you have a boat and have never studied a chart?

[Singularity]

Yes, maps are updated. I assume the only people who pay attention are old-school die-hard types or students in a navigation course.

https://en.wikipedia.org/wiki/Magnetic_declination

[Stu Jackson]

Originally Posted by Singularity

Yes, maps are updated. I assume the only people who pay attention are old-school die-hard types or students in a navigation course.>>>>>>>>>>>>>

I resemble that remark!!!


Really I navigated just yesterday and the entire day before with just GASP! paper charts, no GPS.


Sure, inland coastal in the Gulf Islands, but ya gotta count the islands as they go by so ya know where you were and are.


It's a fun technique I've been using for five + more decades.


Try it sometime, you'll like it!

[David M]

It is fun navigating the old school way and probably a good idea as a backup so one is not 100% dependent on only one method.

[knot smart]

Yup, just drinkin and thinkin and making conversation.. The nature of the question is; how regularly are they updated? Annually? Or every few years?. And no, I definitely don't recall ever seeing anywhere on a chart the words "magnetic variation is abcxyz" ...based on your answer, I had to look for myself. Yes, you're right. It's printed smack dab in the middle of the chart. The chart I looked at was from 2017. And it says right on it "annual decrease 1 degree "...just never noticed it.. I'm always using the chart for scouting purposes , not navigation..see that, learn something new everyday!

[JPA Cate]

Originally Posted by knot smart

Yup, just drinkin and thinkin and making conversation.. The nature of the question is; how regularly are they updated? Annually? Or every few years?. And no, I definitely don't recall ever seeing anywhere on a chart the words "magnetic variation is abcxyz" ...based on your answer, I had to look for myself. Yes, you're right. It's printed smack dab in the middle of the chart. The chart I looked at was from 2017. And it says right on it "annual decrease 1 degree "...just never noticed it.. I'm always using the chart for scouting purposes , not navigation..see that, learn something new everyday!

Hello, Knot Smart,

The paper charts we have state what the magnetic variation for different places is. For example, it's about 14 deg. in Tasmania, where we sailed north from. It is less here near Sydney. The charts have printed upon them what the rate of change is. Some places it's about a degree per year, but it does vary.

I do not know how often the charts are updated.


Ann

PS. Just my opinion, but I think it is easier to conceptualize the geography involved using paper charts, all the detail is right there, your eye zooms on it automatically, you see what you have to change scale to see if using electronic charts. ....and incidentally, getting paper charts wet with sea water does not necessarily destroy them: we got some wet on a trip, and dried them in the cockpit over a few days. The ink stayed fast, didn't run, and the paper dried out. There's a lot of chat on the internet to the effect that all your charts must be up to date, but the truth of the matter is that the rocks and hazards don't move much, or fast, for the most part, although man may add new ones, but those are usually lit.

PS. Definitely, I'm not a science geek.

[Don C L]

Actually it's not a bad question because though charts are updated and each compass rose has the yearly variation change, I believe the speed and acceleration of the poles' movements recently may call into question what is printed on the most recent charts.

[knot smart]

Ann, I completely agree on it being easier to conceptualize .. I always plan ours trips using a regular chart. It's so much easier. I find having to constantly zoom in and out on the plotter to be a major pain. I like to formulate the rough plan at home on a regular chart and when we get to the boat, set the way points and go.

[knot smart]

Originally Posted by Don C L

Actually it's not a bad question because though charts are updated and each compass rose has the yearly variation change, I believe the speed and acceleration of the poles' movements recently may call into question what is printed on the most recent charts.

Don, my recollection from the last article I read was that the poles were changing about 60ft every year. Maybe I'm remembering it wrong, wouldn't be the first time. I was impressed when this article stated 50km a year. I'm mean seriously, that seems like a lot.

[Reefmagnet]

Something like this may help with older charts...


Magnetic Declination

[Don C L]

Originally Posted by knot smart

Don, my recollection from the last article I read was that the poles were changing about 60ft every year. Maybe I'm remembering it wrong, wouldn't be the first time. I was impressed when this article stated 50km a year. I'm mean seriously, that seems like a lot.

This is not a very scholarly article but I believe it captures the recent studies accurately. 50km is the more correct number. But its speed and direction have not been moving at a steady rate lately too as I recall. I'm not sure where I read that, gotta look for it.
https://www.newsweek.com/earth-magne...moving-1412603
By the way, I have not read yet anyone saying there is an imminent flip in the works, but it's not ruled out.
This one's better, but I'll keep looking.
https://www.nature.com/articles/d41586-019-00007-1
From what I can see I was wrong about it taking any turns. It looks like its on a fairly straight trajectory.

[Singularity]

Originally Posted by Don C L

...From what I can see I was wrong about it taking any turns. It looks like its on a fairly straight trajectory.

I'm not certain to which self-correction you're making, but the isogonal lines themselves do meander relatively erratically with respect to each other, presumably a function of the underlying rolling/boiling molten core (meandering depicted on the animated map halfway down this wiki page: https://en.wikipedia.org/wiki/Magnetic_declination).

For dog lovers, I'll repeat a tangential trivial point referenced in another thread, which is that dogs have on on-board magnetic sensing system...tending to relieve themselves with respect to magnetic fields, preferring north/south (thought I think they are influenced by Van Allen belt activity more than a compass is). See:
https://www.pbs.org/newshour/science...ld-study-finds
https://frontiersinzoology.biomedcen...742-9994-10-80

[SeanPatrick]

From NavList:

Originally Posted by Frank Reed

The speed of the north magnetic pole has barely changed since the beginning of the century. There are some issues here, yes, but they have no bearing on any practical navigation issues. The north magnetic pole did not "speed up" but it did defy some educated guesses that it would finally slow down. That's about it. For most mid-latitude navigators, there is no measurable effect.


Note also that there is a coordinate effect at work here. The longitude of the magnetic north pole is changing rather rapidly right now because the pole is passing through very high geographic longitude. Even without changing its speed over the ground, its rate of change in longitude accelerated sharply a few years ago.

Click here to see the original post in its entirety along with some interesting maps.


(Note: Frank is a cartographer by trade.)

[GordMay]

The World Magnetic Model (WMM) is a joint effort from BGS and the NOAA NCEI, on behalf of the UK’s Defence Geographic Centre and the US’ National Geospatial-Intelligence Agency.
Typically, a new and updated version of the World Magnetic Model (WMM) is released every five years. With the last release in 2015, the next version was scheduled for release at the end of 2019. Due to unplanned variations in the Arctic region, scientists have released a new model (MIL-PRF-89500B) to more accurately represent the change of the magnetic field between 2015 and now. As Earth's magnetic field evolves between the 5-year release schedule of the WMM, these predicted values can become off, as the rate of change in Earth's magnetic field evolves, due to unpredictable flows in Earth’s core. The north polar region is experiencing one of these erratic changes. Since the mid-1990s, the pace of the shift (from Canada towards Siberia) has increased from 15 kilometers per year to around 55 kilometers per year.
NCEI ➥ https://www.ngdc.noaa.gov/geomag/WMM...PRF-89500B.pdf
BGS ➥ World Magnetic Model (WMM) | BGS Geomagnetism

Calculator ➥ https://www.ngdc.noaa.gov/geomag/cal...ml#declination


As always, the ultimate source of accurate information remains the CF:

➥ http://www.cruisersforum.com/forums/...on-212668.html

➥ http://www.cruisersforum.com/forums/...ift-56266.html