UKC

For the next few years the magnetic variation in Great Britain is going to be very small.    If you happen to be navigating in the South West then you will be pleased to know that the Magnetic Variation by July 2018 is effectively zero.  For all parts of the country the variation is going to be so slight that it will be possible to ignore it.  However if Magnetic North continues to move in the same direction we will eventually have to pay attention again and by then I hope someone will have come up with a ditty to help navigators remember the new state of affairs. Any good suggestions out there?

we could number compasses anti-clockwise.

variation east magnetic is least. 

Been around for years amongst aviators and nautical navigators 

Is this a result of brexit?

From sailing, the never-forgotten order of application:
Timid Virgins Make Dull Companions (True Variation Magnetic Deviation Compass). So, sure, we're not dealing with True or Deviation here, but the logic of the order remains.

In reply to Tim Davies:

Error west, compass best.

Error east, compass least.

Of course we shouldn't be dealing in superlatives when comparing two things, but simple comparatives don't rhyme!

Needle to Norway, Map to the Cap

I’ve been ignoring it for years - could explain a few things.

How many years are we taking about. 

Last time I messed about with adjusting compass bearings for magnetic deviation was in the 80s. It always seemed an academic extercise to me. The only time you really need it is if you’re doing back bearings and even then it never seemed particularly far out. 

Depends how long the bearing leg is. A five degree error (about what it was when I were a lad) over 2km is 85m out - for mountain marathon navigation purposes that puts you a whole search box away.

b

simple they will do what they did when the rest of the world was using UTM. Pick up the whole of Britain and move the datum to one side in order to keep the old format.
I am talking on a map based basis here.

In the Falklands I had to explain to a bunch of soldiers that what they had been taught was WRONG. Unfortunately military training is good at teaching fact as absolute and trying to re-teach people and even getting the arsehole officers to accept that magnetic variation isn't always east was a hard slog.  

We were taught "Manchester Grammar School" for "Map to ground subtract". 

It's probably now become an academy, so that's all OK. 

In the 70s I learned MUGS (Magnetic Unto Grid Subtract)

(Only a mug forgets his mugs)

MUGS I think I will change to MUGGA (sounds like Mugger)

Be safe, Look out for Muggers

Magnetic unto Grid Add.   But I might not live long enough to need it of course

I could never remember  the military method of adding/subtractingfor back bearings so I just used the S end of the compass needle and took a bearing (works in the UK) and is quick

It has always been a flawed method, as it's not universally applicable.

The much better method is to use the map annotation, which shows the local difference between grid and magnetic norths, and the yearly variation. If it isn't marked on the map, find out the local difference, and draw it on your map.

You simply have to remember to turn the compass capsule the appropriate number of degrees when changing from grid to magnetic, or magnetic to grid.

If, for instance, you take a magnetic bearing, and want to convert to a grid bearing, if grid N is W of mag N, rotate the capsule to the W (anticlockwise); if grid N is E of mag N, rotate the capsule to the E (clockwise). Don't look at the numbers on the capsule dial as you do it, just concentrate on how many degrees you have to move it, and in which direction. Once you have moved it, then you can take the reading (if needed).

Whatever the capsule position, and how you are holding the compass, imagine a N arrow pointing to the 'top' of the capsule. Then, looking at the map annotation, it should be obvious what to do to convert from mag to grid, and vice versa.

All you are doing is moving the capsule N between the two little N arrows on the map legend. Use the numbers, not the actual arrows, since the arrows may be schematic only, and do not necessarily depict the actual difference.

I have used a true grid compass for a while. Problem solved.

?

I've never bothered at all is that bad?

I presume he meant a compass with the ability to set a declination offset. e.g.

http://silva.se/product/compasses/compasses-outdoor/expedition-s/

ps. Of course, they really mean grid magnetic angle, of which declination is only one component...

Try ignoring it in New Zealand.

Declination between 20 and 26 degrees...

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

Proabably not. With a few degrees variation between the map and the compass is very small. More likely that the difficulty of using a compass to 1 degree precision and walking in a straight line are your limits.

I recall MOUNTAIN= SUBTRACT, MAP=ADD, the link being that each has the same number of letters. Can't for the life of me remember where I picked that up from but it seems to have stuck.

I'm sure it was huge (about 8 or 9 degrees) when I was young in early to mid 60s. We just had 'map to terrain' add and v.v. (map being a shorter/smaller word than terrain) as the mnemonic.

If you have a phone in your coat pocket the magnets in the loudspeakers are probably moving the compass needle more than a degree.   

Those mnemonics have always seemed unhelpful to me, since, as your first posting implies, they only 'work' when the declension is one way (west, in the case of the UK); i.e. they're not applicable planet-wide. Of course, you could make up fancier ditties - but I've always found the best way is simply to mentally 'draw in' the magnetic grid lines on any particular map. Then, the necessary adjustment (either from the map to the field; or vice versa) becomes instantly obvious, and there is no scope for confusion.

As has been pointed out above, you can more-or-less ignore declension in the UK at present - but in some countries, it really matters.

Well yes, then it's worth it! As a child of the early 90s its never made much difference during my lifetime, never being more than a few degrees.