Why Are Magnetic Declination Charts Useful for Hikers?

Understanding Magnetic Declination

Magnetic declination is the difference between magnetic north and true north, varying depending on geographical location. A magnetic declination chart provides a map of these variations, enabling hikers to adjust their compass readings accordingly. Typically, declination ranges from -20 to 20 degrees, with most areas experiencing a declination of around 10 degrees.

Charting the Course

To use a magnetic declination chart, hikers need to identify their location on the chart and note the corresponding declination value for that area. For example, if hiking in the Pacific Northwest, a chart may show a declination of 15 degrees west. This means that the magnetic needle on their compass will need to be adjusted 15 degrees to the west to align with true north. It’s crucial to update this value periodically as declination changes over time, often at a rate of about 0.5 to 2 degrees per year.

Navigating with a Declination Chart

When using a magnetic declination chart, hikers should follow these steps:

1. Identify their location on the chart and note the declination value.
2. Adjust their compass by the declination value to ensure accurate north readings.
3. Use the adjusted compass to navigate through their route.
4. Periodically update the declination value as it changes over time.

By incorporating magnetic declination charts into their navigation routine, hikers can ensure accurate and reliable compass readings, reducing the risk of disorientation and increasing their overall safety on the trails.