The difference between magnetic north and true north that is typically several degrees is called what?

Prepare for the Water Survival 929 Test. Use flashcards, multiple choice questions, hints, and explanations. Get water safe!

Multiple Choice

The difference between magnetic north and true north that is typically several degrees is called what?

The difference between magnetic north and true north is measured as magnetic declination, also called variation. The Earth’s magnetic field isn’t aligned with geographic north, so a compass points toward magnetic north while maps and charts are drawn relative to true north. This angle varies by location and over time, which is why charts show a local declination value. You use this by adjusting bearings: if magnetic north lies east of true north, you add that declination to convert true bearings to magnetic bearings, and subtract it to go the other way. If it lies west, the opposite adjustment applies. In practice, this lets you translate between the direction your compass shows and the actual geographic direction you intend to follow. Compass error is a broader term that can include local influences on the compass itself (like nearby metal), not the natural difference between true and magnetic north. Deviation refers to those local effects on a specific vessel or instrument, separate from the global magnetic declination. Variation is another name for magnetic declination in many contexts.

The difference between magnetic north and true north is measured as magnetic declination, also called variation. The Earth’s magnetic field isn’t aligned with geographic north, so a compass points toward magnetic north while maps and charts are drawn relative to true north. This angle varies by location and over time, which is why charts show a local declination value.

You use this by adjusting bearings: if magnetic north lies east of true north, you add that declination to convert true bearings to magnetic bearings, and subtract it to go the other way. If it lies west, the opposite adjustment applies. In practice, this lets you translate between the direction your compass shows and the actual geographic direction you intend to follow.

Compass error is a broader term that can include local influences on the compass itself (like nearby metal), not the natural difference between true and magnetic north. Deviation refers to those local effects on a specific vessel or instrument, separate from the global magnetic declination. Variation is another name for magnetic declination in many contexts.

More practice questions