Whenever you transfer a magnetic bearing taken in the field to your map, you add the magnetic declination to get the true bearing. Whenever you transfer a bearing taken from your map to the field, you subtract the magnetic declination to get the magnetic bearing to follow.
How do you know when to add or subtract magnetic declination?
An easy way to remember whether to add or subtract is ” West is best and East is least.” So for West declination, add to the true reading (West is best, and therefore a larger number) and for East declination subtract from the true reading (East is least, and therefore a smaller number).
Do I add or subtract magnetic variation?
Use this mnemonic to remember that with variation west, the magnetic direction is going to be “best” or greater than true. Variation is added to true to arrive at magnetic, or subtracted from magnetic to get true. With variation east, magnetic will be “least” or less than true.
How do you compensate for declination?
To compensate for declination:
- Align the north arrow (the N) of the azimuth ring along a north/south line on the map.
- Check the diagram at the bottom of the map that shows whether magnetic north is to the left or right of true north.
Should I use magnetic or True North?
As it turns, Magnetic North is much more important than True North. The Magnetic North pole is also known as a “dip pole” and, along with Magnetic South, is where the Earth’s magnetic field is at its weakest.
How do you write magnetic declination?
Isogonic lines are lines on the Earth’s surface along which the declination has the same constant value, and lines along which the declination is zero are called agonic lines. The lowercase Greek letter δ (delta) is frequently used as the symbol for magnetic declination.
What is left add right subtract?
If you moved left you should add the angle between grid and magnetic; if you moved right, you should subtract. This concept of LEFT ADD, RIGHT SUBTRACT is known as the LARS Rule.
How do you add declination to a compass?
Turn the compass over. Insert the metal key (provided with your compass) into the adjustment screw. Turn the key until the declination indicator is the correct number of degrees east or west of 0° (15.6 degrees West in this example).
What is declination on a compass?
At most places on the Earth’s surface, the compass doesn’t point exactly toward geographic north. The deviation of the compass from true north is an angle called “declination” (or “magnetic declination”). Declination is simply a manifestation of the complexity of the geomagnetic field.
What is the difference between magnetic variation and declination?
“Magnetic north” is the point on the Earth’s surface where its magnetic field points directly downwards. Magnetic north does not exactly coincide with true north, and its location changes over time. The difference between Magnetic North and True North is called “Declination” or “Variation”.