Another way to remember if you need to add or subtract is as follows: If you going from a grid to a mag bearing then 'add' because the world is bigger than the map. If your going from a magnificent bearing to a grid bearing then subtract/takeaway as the map is smaller than the world. This has helped quite a few students I have taught with dyslexia .
This is the best land navigation site that I have come across. Techniques are clear and concise, no sidebars yapping about this and that while someone is trying to learn something new.
Hi mr Steve I really appreciate your great and successful effort This is been wonderfully explains everything I’ve watched 20s of videos about it but couldn’t get my head around I’ve learnt everything in these short 8 videos Wonderful Steve I can appreciate your knowledge and hard working and thinking for how to make a Beginner understand Very helpful Thank you
Too fast, lacks detail. Even on pause i have no idea what he is aligning with what. i can see the 5 degrees W declination on my compass, now what? Do I ignore the gig red arrow in the bezel?
The BGS website is also not very good for finding a quick degree figure for a particular location - it's far too specialist for this purpose. This is easier - www.magnetic-declination.com/.
yep agree could have explained it better for the purpose of using your own map for your area...although less than 2 degrees is not much of an adjustment to make
Because of the coming micronova, declination is moving much farther, and much faster and so declination information is likely incorrect but there is still a way to recalibrate magnetic declination using the shadow of sticks recording the path of the sun---rotation of the earth has not yet changed. First stick will show East. Mark it with a sharp stick pushed in. After a few minutes you can mark sun shadow travel where the shadow has moved - Push another stick in to mark West. Lay a straight stick from the E mark to the W mark. Geographic north or True North is 90 degrees from the E-W line. With your compass pointing toward True North, note how far off your compass is now. That is your true up-to-date declination. My up-to-date declination is 30 degrees, 15 degrees off from the official declination for my area. More on micronova in my 2nd book, Surviving the Micronova: This Train Is on the Tracks will be available in September.
The variation data on the legend is only correct at the date the map data was collated - not even when it was bought. I have some very old maps which are still useful but the variation is now significantly different to what they say. So before setting out on a trip, I get the OS grid reference more or less central to the area I will be visiting and head off to www.geomag.bgs.ac.uk/data_service/models_compass/gma_calc.html From there I can get recent data and know the correct correction (if you see what I mean)! If you have a posh compass which can be adjusted to allow for this, you can also do that before you go - but keep a note of it anyway just in case it gets lost and must be replaced during the trip.
mistake in video.....you will sometimes hear people talk of magnetic declination, when they really mean magnetic variation in the UK. Declination is different, as it is the measure of the difference between true north and magnetic north, and as we in the UK don’t need to concern ourselves with True north, we can forget the proper definition of declination
You have copied and pasted text from www.mountainsafety.co.uk/Nav-Magnetic-Variation-Declination.aspx to make your point. You are correct but it would be helpful to expand a little by explaining that we don’t need to concern ourselves with declination in the UK because our maps are aligned to a “grid North” which is neither True North nor Magnetic North. Consequently, magnetic variation is the angle between magnetic north and GRID North whereas magnetic declination is the angle between Magnetic North and True North. In the majority of the rest of the world however, maps are aligned with true North so for anyone navigating outside the UK (or pedants like myself) it’s good to know about declination as well.
@@CaptainBirdSi68 depends how old the map is. I have some 20 years old, Walking short distances in the uk is probably fine, We can still wonder off course, going long distances so whats a few degrees. its good practice to do the calculation
This didn't really explain anything about the magnetic declination on OS maps. I'm a begginer to map reading, and maybe I'm missing something, but there was zero information in this clip.
We're sorry this video didn't help you Gary. The information and links on our blog may help: www.ordnancesurvey.co.uk/blog/2019/03/magnetic-north-continues-its-march-to-the-east/. If you need further assistance, please email us at customerservices@os.uk.
If we may add, and with the caveat that we are amateurs and the trouble with theory is that you need to make it work in practice: Magnetic declination is the difference between magnetic north shown on compass and the gridlines on maps, where these maps use true north (the North Pole) for referencing their vertical gridlines. The UK situation is slightly different due to the standardised layout of the National Grid, which is in turn referenced by OS to draw gridlines on OS maps. So square and 2D area representations of what are in reality curved and 3D surfaces of the globe. Only one of the north/south National Grid meridians (vertical gridlines), broadly at the centre of the entire National Grid map projection is aligned to true north. The rest veer off slightly either east or west. OS maps therefore state the necessary correction to account for the difference between their grid lines and magnetic (compass) north as it reads when navigating in various parts of the UK. This correction is specific to the area being mapped and known as grid magnetic angle. A final complexity is that magnetic north itself is shifting position over time, so the correction for grid magnetic angle in the present has to take this into account. Your printed OS map has 'fixed at the time of printing' gridlines, but your compass is following ever drifting magnetic north! The explanation for grid magnetic angle correction provided on your 1:25,000 (and some other scale) OS map will state the correction for the year it was published and the additional corrections for navigation in future years. All of the above is to say that it is useful to have a first principles understanding of both your specific map projections and the general method of compass and map wayfinding. Relying on heuristics and catchy mnemonic phrases, while very often an excellent way to learn, in this case is sometimes unhelpful as they oversimplify. In many instances, popular navigation catchphrases are inaccurate applied to the UK or now out of date. Hope that helps. If this is incorrect please correct us! And as ever there's no substitute for the field.
ok that website is exactly wats needed and is now saved thx ,however my gripe is if you only have a map in front of you ,The explanation on the map legend does not read easily,(to me anyway) however now I have that website I no longer need to try and decipher wots written ,I am doing the "fan dance" Wednesday and according to your website there is less than one degree variation which isn't worth worrying about anyway + theres a well trod footpath by the looks of it 8-) .many thx and apologies,was having a bad night .colin
Grid to Mag add is gradually losing its relevance in the UK. If you are in the far west its already wrong, and as you head towards the middle there is no meaningful difference at all. Its only in the East we still use it and even then we're only at about 2 degrees and closing.
Yes, these videos are 5 years old now, so made when the change was only just to the west of Penzance. You can see our blog on the topic here though and the link to calculate the latest figures: https:www.ordnancesurvey.co.uk/blog/2019/03/magnetic-north-continues-its-march-to-the-east/
He has slightly cocked up his terminology in this video....The different between grid north and magnetic north is irrelevant....Grid north is simply north on your map...The top edge of it....The difference between True North (north pole) and magnetic north is what's known as Declination.....Map north has nothing to do with it.
Honestly this is a bit rubbish. The declination and G-M angles are give in degrees and minutes rather than decimal degrees. And the estimated annual variation is also given in minutes. This makes it a total pain to actually calculate in the field. Why not provide it in decimal degrees I have no idea. And for all the room the diagram takes up it really isn't helping the reader to apply the G-M angle adjustment.
