Magnetic Declination - a VERY simple explanation
Вставка
- Опубліковано 27 вер 2024
- This is the simplest video description of Magnetic Declination you will find online. Declination is simply the difference between True North and Magnetic North. In this video we go through why Magnetic Declination exists and also, again in a very easy to understand way, how to adjust your compass to cope with declination.
I enjoy watching your videos... I've been a land nav chap for going on 6 decades but I watch because I love your relwxed, waffling style!
You're absolutely spot on... declination means little for a trek in the bush with map & compass...
but it's extremely important in sailing .... it's rather a hootenany to take a chart/map and fix a line without taking declination into account and see just how far off the mark you'd be, say, over a 3000 nautical mile distance.
Anyway.. great stuff, mate! Keep keeping it simple... and never stop the waffle! Lots of good info in the waffles! Cheers!
To clarify, he didn't say magnetic declination means little for hikers. He said the difference between true north and grid north (grid variance) means little for hikers but does matter for nautical or aerial applications over longer distances
Another lesson from The Map Reading Company that really helps drive this home is the WAvES declination method video. Thank you TMRC for the help you provide.
To illustrate a few of your points, a 1960 map from this area (1500 km NNW of Utah) shows a declination of about 23 degrees. Today, it's close to 15 degrees. Grid north is only about 1.5 degrees from true. Always interesting to watch your videos.
Excellent breakdown and description. Makes it very simple to understand... Cheers
A few days ago i became an answer from the KMI, the Royal Meteorological Institute (Belgium) about a question i asked them concerning the magnetic South-Pole.
In that answer they write the shift of the magnetic North-pole was about 5 Km annually. Since ± 1990 it's speeding up and since some years it becomes a yearly shift of ± 50 Km annually.
The magnetic South-pole also moves yearly but many slower as the magnetic North-pole. The shift of the magnetic South-pole, on the other hand, remains quite stable.
There are lots of sayings for declination, but the one I found easiest to use and remember:- Declination EAST, compass LEAST. Declination WEST, compass BEST. In the above example of EASTERLY deviation, if you want to follow a map bearing, the compass has to be LEAST, so you take the deviation off the map bearing to get a magnetic bearing. If you want to plot a compass bearing on to the map, the compass still has to be LEAST, so you add the deviation on to the compass bearing to plot the course on the map. I don't mean to be a teacher here, but I have seen so many struggle with deviation calculations. Conversely use the compass BEST for westerly declinations. TMRC, if I am out of turn just delete this, no umbrage taken.
As usual I start watching your videos with a like. In this case I was “first”.. yeah for me. Funny thing, counter didn’t chance to 1 but remained 0! So… I don’t count hahaha.on video topic, a find it amazing when looking to a movement map of the true north magnetic pole! It changes “constant”!
Thank you for this video!
I find Navigation in General Fascinating. I was dating a GAL 15 years ago before G maps and we where in residential neighborhoods in a hurry to get to a very important B-Day Party and I kept asking here which way North was as she was looking at the map and she kept saying North is Up!!!!😂😂😂😂…. If that don’t want a person to learn about Nav. Nothing will!!!! 😂😂😂
CAMS
Compass Add Map Subtract
Is that for east declination or west?
East
The simplest thing to do is to extend the declination line shown at the bottom of your map unto the map and then duplicate that line in parallel across the rest of the map. Then, instead of finding a grid bearing by aligning your compass bezel to the map grid you can align it to a declination line and read the magnetic bearing directly off the map.
On UK maps this isn’t possible as the declination graphic on the map is not drawn to the amount of declination - it’s just a diagram.
Great explanation of declination and magnetic vs. geographic north poles. Would you happen to know what creates the magnetic north pole? Is it the rotation of the earth on its axis or is it the composition of the earth below its crust? It seems to me that the rotation is the causative factor in the creation of the magnetic north pole since that specific location tends to vary slightly from year-to-year as does the axis. Am I close? Thanks.
I wrote a blog about this a while ago - I may do a video one day. Here is the explanation of what creates the Magnetic North Pole. mapreading.co.uk/why-the-magnetic-north-pole-moves/
@@TheMapReadingCompany Thank you! That is an excellent explanation in your blog. Well done!
MuGS - Magnetic unto Grid Subtract GuMA - Grid unto Magnetic Add (Westerly Declanation) or MuGA - GuMS (Easterly Declanation).
good video.
Im not sure about this - but I think I´ve heard you say that you can´t take a bearing from a map with a compass with dialed in declination - you have to "zero" the declination of the compass to take the bearing from the map - and then punch in the declination to the compass before useing the bearing in the terrain. Is that right?
If you have a compass which you can pre-set the declination then you can use this to take the bearing from the map - don’t forget to use the orienting Lines, not the orienting arrow. The compass I used on the video can’t be pre-set so I had to subtract the declination after I took the grid (map) bearing.
Sorry for any confusion.
@@TheMapReadingCompany ok, thanks for clarifying that. I love you videos. You do a amazing job!! 😉👍
👍
If I'm standing on the south pole and my compass points to the north pole, how does it work on a sphere?
It makes more sense on flat earth and north pole is center of our topographical realm.
If you were at the South Pole all directions are north so your compass would either spin or not work (as the mag fields
are pointing upwards)
Hi. I am interested to know more about the Brunton compass used in this video. Not sure I have seen a compass with curved sides before, is that for decoration or do they serve a purpose? Also what are 3/4 circular cuts for? Thank you.
Hi Chris. The Cut-outs are EPE holes. See the first part of this video for more details.
ua-cam.com/video/LVf0v0TqoOg/v-deo.htmlsi=LKgbWrCbtupk3voV
The compass is a Brunton TruArc 10. You can get some information about this on the Brunton site.
Thank you for the explanation, I appreciate it. That video is what lead me to your channel and to me subscribing. Cheers.
It should also be remembered that a compass is not an "end it all" device. The information gleaned from a compass, north or south etc, must be used in conjunction with other local landmarks and waypoints to orientate your directions. I can't think of anyone who would be involved in navigating who would rely solely on a compass alone.
Grid to mag add mag to grid get rid.
That only works in half of the world. And it doesn't work in Salt Lake City
That only works with western declination. The UK actually has both east and west declination at the moment, depending on which side of the country you're on and my area, in the midlands, has basically no declination at all
@@waelisc interesting.Thanks 👍
Heard it is opposite in Australia
I love your stuff but I have to be honest, not the best descripion of mag. declination i've come across.
Thanks for the feedback Shaun.
what no waffle?! 😉
I sneaked in the bit about the North Pole being the south end of the magnetic field 😊
A minor waffle... wouldn't be a proper video without it. 🤷
MAG EAST + GRID - IN EAST PLACES. opposite for west. Best to write this on some tape and put your one on your compass so you dont have to remember it.