swirl error

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The Information Architects of Encyclopaedia Britannica

Last updated

July 14, 2026

Quick Summary

The term "swirl" refers to causing something, often a liquid, to move in a circular motion. It can also describe moving an object in a curved or circular path.1

In the context of navigation, "swirl error" is a phenomenon that can occur with liquid magnetic compasses. These compasses contain needles and a card floating in a liquid mixture of water and alcohol. When a ship changes course, the liquid can shift, causing the compass card to deflect. This deflection is known as swirl error. To minimize this error, the compass card is typically made smaller than the bowl it sits in.2

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The liquid magnetic compass
…causing what is known as swirl error. To minimize swirl error, the card is often made considerably smaller in diameter than the bowl. The directional system is made sufficiently bottom-heavy (pendulous) to counteract the downward pull of the vertical component of the Earth’s magnetic field, which would otherwise cause the…
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…causing what is known as swirl error. To minimize swirl error, the card is often made considerably smaller in diameter than the bowl. The directional system is made sufficiently bottom-heavy (pendulous) to counteract the downward pull of the vertical component of the Earth’s magnetic field, which would otherwise cause the…
Read More