Quick Answer
Adjust for declination by adding or subtracting the declination value to your compass bearing. This means if the declination is positive, you add it to the bearing, and if it's negative, you subtract it.
Understanding Declination
Declination is the difference between magnetic north and true north, and it varies by location. To adjust for declination, you need to know the declination value for your location. In the United States, declination ranges from -20 degrees to +20 degrees, with most areas having a declination of around 10-15 degrees. You can find the declination value for your location using a declination chart or by consulting a map.
Measuring and Applying Declination
To apply declination, you need to understand how to read your compass. The direction-of-travel arrow on your compass points towards magnetic north. If you want to travel in a specific direction, you need to set the direction-of-travel arrow to point towards that direction. To adjust for declination, you need to add or subtract the declination value from the direction you want to travel. For example, if you want to travel north and the declination is 10 degrees east, you need to set the direction-of-travel arrow to 90 degrees (north) + 10 degrees (declination) = 100 degrees. This means you need to travel at a bearing of 100 degrees to head in the direction you want.
Tips for Using Declination
When using a compass, it’s essential to understand the relationship between magnetic north and true north. If you’re not using declination, you risk being off course by several degrees. Declination is especially important in areas where the declination value is high, such as near the poles. It’s also essential to understand that declination can change over time, so it’s crucial to check the declination value regularly, especially if you’re traveling to a new area.
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