1. SnaggyBloke1664

    SnaggyBloke1664 New Member

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    quick quezy:
    I've always been taught to calculate the GMA on any map you find difference of map date, to today's date (so map in 2010 to now is 6) then multiply the difference in mills it changes per year (etc 3 mills a year from W-E).. Finally minus this answer from the maps GMA (eg 70) . E.g 6x3=18 70-18=52=GMA.

    But now I'm told that magnetic north has changed to the east of grid north (as of 2015), so now we would add rather than subtract (e.g 70+18 as seen above), going from East-West.
    Could someone with recent map reading knowledge clear this up please?
    Cheers
     
  2. R4Robotics

    R4Robotics Spectator

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    Who has told you that?

    It is still taught as -
    (Year Now) - (Map Year) = No. Years

    No. Years x Annual Change = Total Change Map

    GMA - Total Change = GMA
     
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  3. DhobiWanKenobi

    DhobiWanKenobi Royal Marines Commando

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    I know the angle has been getting smaller but not sure if it has changed to east yet, don't have a map from this year right now to find out.
     
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  4. SnaggyBloke1664

    SnaggyBloke1664 New Member

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    Think this has just come about, saw it online somewhere. Plus according to RM map reading disc I have the rules of GMA where due to change end of 2015?
    I know other European countries are already sitting east of grid north, but not sure when that affects the UK.
     
  5. R4Robotics

    R4Robotics Spectator

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    I'm not close enough to that side of things and as the maps I use are years out of date - its not going to affect me anytime soon - Will watch "this space" and find out
     
  6. thegingerone

    thegingerone New Member

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    Any updates on this?
     
  7. ERFC

    ERFC Royal Marines Commando

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    All the mapping we’re currently using is 2014/2015 and it’s still to the west of magnetic north. I did some research and it changed around 2014 however due to how slow the change is it’ll still be years before it’s implemented into maps. It also varies from what area you are in. For example Scotland compared to the South East of the UK will have quite a different GMA due to the angle it is from magnetic north.

    As it stands I’ve not heard anything about changing the way we work out the GMA however I’ll discuss it and see if I can find out any more information on this.