Quick Answer
Different magnetic zones can significantly affect compass performance by altering the accuracy of magnetic declination readings. This can lead to navigation errors if not accounted for. In areas with high magnetic variance, compasses may require regular recalibration.
Magnetic Variance and Compass Accuracy
Magnetic variance is the difference between magnetic north and true north, and it varies depending on the location. In areas with high magnetic variance, such as near power lines, railroads, or industrial sites, compass accuracy can be compromised. For example, in the United States, areas near the Rocky Mountains experience high magnetic variance, with some regions having a variance of up to 20 degrees (360 degrees / 18 = 20 degrees for every 18 miles).
Mitigating Compass Inaccuracy
To mitigate compass inaccuracy due to magnetic variance, it’s essential to use a compass with a declination correction feature. This feature allows users to adjust the compass for the local magnetic declination, ensuring accurate readings. Additionally, using a compass with a built-in declination scale or a separate declination chart can help users make adjustments. In extreme cases, users may need to re-zero their compass or use a magnetometer to calibrate it.
Choosing the Right Compass
When selecting a compass for survival or navigation, it’s crucial to consider the magnetic properties of the area you’ll be operating in. Look for a compass with a robust magnetic shield or a compass specifically designed for high-magnetic variance areas. Some popular compass models, such as the Suunto A-10 or the Brunton Global, feature declination correction and are suitable for areas with high magnetic variance. Always read the manufacturer’s specifications and user manual to ensure the compass is suitable for your specific needs.
Find more answers
Browse the full Q&A library by topic, or jump back to the topic this question belongs to.