Memory map question

[+Big Wolf]

Within Memory Map there is a setting called Magnetic Variation. (In V5 this can be found in the Mode menu then Units)

 

According to the Ordanance survey 'Magnetic Variation' is defined as the difference between True and Magnetic North) but if you want to get a magnetic bearing from an OS map then you need a value called the Grid Magnetic Angle

 

If you don't change this setting then Memory Map displays True bearings so the question is, if you want to get magnetic bearings (to solve a puzzle cache) should you use the value for 'Magnetic Variation' or enter the 'Grid Magnetic Angle' (Currently there is a about a 1º difference between the two angles here, which, when projected over 2km makes a big difference in the final cache location!)

 

To find the value for your local Grid Magnetic Angle Click Here

 

To find the value for your local Magnetic Variation Click Here (Note: Magnetic Variation and Magnetic Declination are the same thing)

 

Can any one help as the program manual is as good as useless?

Edited August 5, 2007 by Big Wolf

[+macroderma]

Within Memory Map there is a setting called Magnetic Variation. (In V5 this can be found in the Mode menu then Units)

 

According to the Ordanance survey 'Magnetic Variation' is defined as the difference between True and Magnetic North) but if you want to get a magnetic bearing from an OS map then you need a value called the Grid Magnetic Angle

 

If you don't change this setting then Memory Map displays True bearings so the question is, if you want to get magnetic bearings (to solve a puzzle cache) should you use the value for 'Magnetic Variation' or enter the 'Grid Magnetic Angle' (Currently there is a about a 1º difference between the two angles here, which, when projected over 2km makes a big difference in the final cache location!)

 

To find the value for your local Grid Magnetic Angle Click Here

 

To find the value for your local Magnetic Variation Click Here (Note: Magnetic Variation and Magnetic Declination are the same thing)

 

Can any one help as the program manual is as good as useless?

 

Well what I would do is work out the first, say 2 degrees west, then find the second, say 7 degrees east, apply any corrections to each for the date (although the websites seem to give out data accurate to the month)

 

Then combine them: 2W+7E=5E

 

Then go to the Mode/Units/Magnetic variation menu option to put the calulated variation in

 

After that all you need is to use the route option to start at your bearing origin and then draw out a route line on the appropriate bearing(as you move the cursor the box alongside updates with the bearing[degrees 'M'])