What is variation in navigation?

What is variation in navigation?

• A. The difference between true north and compass north
• B. The rotation of the Earth
• C. The difference between magnetic north and true north
• D. The deviation caused by metals

Answer: (A)

Variation is the angular difference between true north and magnetic north. This happens because Earth's magnetic field isn’t perfectly aligned with the geographic axis, and the difference varies by location and over time. On charts you’ll see a variation value labeled east or west. If variation is east, magnetic north lies to the east of true north, so true heading plus variation gives the magnetic heading, and magnetic heading minus variation gives the true heading when going in the opposite direction. If variation is west, magnetic north lies to the west of true north, and the conversions work with the opposite signs. For example, with 10° East variation, a true heading of 045° becomes a magnetic heading of 055°, while a magnetic heading of 055° corresponds to a true heading of 045°. Variation is different from deviation, which is caused by metals and structure on the vessel.

Variation is the angular difference between true north and magnetic north. This happens because Earth's magnetic field isn’t perfectly aligned with the geographic axis, and the difference varies by location and over time. On charts you’ll see a variation value labeled east or west. If variation is east, magnetic north lies to the east of true north, so true heading plus variation gives the magnetic heading, and magnetic heading minus variation gives the true heading when going in the opposite direction. If variation is west, magnetic north lies to the west of true north, and the conversions work with the opposite signs. For example, with 10° East variation, a true heading of 045° becomes a magnetic heading of 055°, while a magnetic heading of 055° corresponds to a true heading of 045°. Variation is different from deviation, which is caused by metals and structure on the vessel.