Quick Answer
Understanding declination is crucial for accurate navigation because it allows you to account for the difference between magnetic north and true north, which can be as much as 20 degrees at high latitudes.
Declination Basics
Declination is the difference between magnetic north and true north, which is the direction a compass needle points towards the Earth’s magnetic field. This difference can vary depending on your location, with some areas having a declination of up to 20 degrees. To use a compass accurately, you need to know your location’s declination, which can be found on a topographic map or by checking with a local authority.
Calculating Declination
To calculate declination, you need to know the magnetic variation for your area, which is usually expressed in degrees. For example, if the magnetic variation is 15 degrees east, you need to adjust your compass reading by 15 degrees to the west to get a true bearing. It’s essential to note that declination can change over time due to the Earth’s magnetic field shifting, so it’s crucial to update your knowledge of declination regularly.
Applying Declination in Navigation
To apply declination in navigation, you need to adjust your compass reading based on the declination for your area. For example, if you’re trying to get a true bearing, you need to add or subtract the declination from the magnetic bearing. If you’re traveling with a compass, it’s essential to set the declination on your compass before use, usually by turning a bezel or adjusting a button. This ensures that your compass is giving you accurate readings, which is critical for navigation.
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