Brisbane has a Magnetic Declination of 11 degrees East. That is, Magnetic North is 11 degrees East of Grid North, where Grid North is a line of longitude that “points” to the NCP of the axis of rotation of the Earth.
So, in Brisbane, I need to “offset” the magnetic needle on my compass 11 degrees to the East, that is, 180-11=169 degrees as seen on the white, inner, rotating bezel. See attached file.
So, for Perth, if the Magnetic Declination is 2 degrees West, then Magnetic North lies 2 degrees West of grid North. So, using the same logic, in the attached (1st) diagram the inner white bezel would read 182 degrees.
Hope that helps and better still, hope that I’ve got it right!
Cheers
Dennis
PS - Link to
Mag Dec maps here