compass card
Quick Summary
A compass card is a navigational instrument that displays directions. Historically, before the widespread use of magnetic compasses, wind roses on charts served as guides for sailors, indicating the directions of the eight principal winds.1
The modern compass card, often combined with a magnetic compass, shows wind frequency and strength. It typically features eight radiating lines, with lengths proportional to wind frequency. Wind strength can be indicated by the thickness of these lines or attached feathers. Calm air percentages are shown in the center.1
The development of the compass card involved mounting a painted wind rose on a needle. This allowed navigators to read their heading directly from the card. Early compass cards marked cardinal directions, and over time, the system evolved to include 32 points. The magnetic compass works because Earth acts as a large magnet, causing a freely moving magnetic pointer to align with its magnetic field.234
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compassA card with the points painted on it was mounted directly under the needle, permitting navigators to read their direction from the top of the card. The bowl itself was subsequently hung on gimbals (rings on the side that let it swing freely), ensuring that the…
Read MoreA card with the points painted on it was mounted directly under the needle, permitting navigators to read their direction from the top of the card. The bowl itself was subsequently hung on gimbals (rings on the side that let it swing freely), ensuring that the…
Read More- magnetic compass
…which the north on the compass card and the “needle north” were the same when the ship passed a point in Cornwall, England. (The magnetic poles, however, wander in a predictable manner—in more recent centuries, Europeans have found magnetic north to be west of true north—and this must be considered…
Read More…which the north on the compass card and the “needle north” were the same when the ship passed a point in Cornwall, England. (The magnetic poles, however, wander in a predictable manner—in more recent centuries, Europeans have found magnetic north to be west of true north—and this must be considered…
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navigationThe lodestone and the compass cardBy the 13th century a card bearing a painted wind rose was mounted on the needle; the navigator could then simply read his heading from the card. So familiar has this combination become that it is called the compass, although that word originally signified the division of the horizon. The…
Read MoreBy the 13th century a card bearing a painted wind rose was mounted on the needle; the navigator could then simply read his heading from the card. So familiar has this combination become that it is called the compass, although that word originally signified the division of the horizon. The…
Read More