Map Reading Tips- Part 3 – North, North and North

Did you know that the north on your map can be different to the north on your compass? and the north on your compass and map is also not the same as true north? This fact can often be overlooked and can effect the outcome of your navigation.

mag_diagram_eng_gmt
Diagram from British Geological Survey

Grid North

Grid North is the north as it appears on a map and the north that we use for taking bearings

Magnetic North

This is the direction your compass needle points too and is the direction you will use as north when navigating.

True North

This is the actual north where you will find the geographical north pole. If you were to draw a line from your location to the north pole this would be the true north.

Converting map north to grid north and visa versa

Converting between grid north and magnetic north is fairly simple, the difference between grid north and magnetic north is about 2 degrees west so we need to ensure our bearings are corrected to take this into account.

When you take a bearing on your map the magnetic north will be 2 degrees west. So if your bearing is 298 degrees you will need to add 2 degrees to your compass to ensure your aiming in the right direction, this will give you a bearing of 300 degrees.

When your converting a bearing from your compass to the map you will need to subtract 2 degrees from your compass to give you the map bearing, If your bearing on the compass is 300 degrees you will need to subtract 2 degrees to give your bearing on the map, this will give you a map bearing of 298 degrees

a popular way to remember this is (Grid To Mag Add) ( Mag To Grid Get Rid)

Further reading

Ordnance surveys blog about the different Norths.

British Geological Survey blog

Thanks for reading, this blog was developed as part of National Map Reading week.

For more information about me and my navigation courses visit my Facebook page.

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