Pingzhou Ketan

Zhu Yu records Chinese mariners using a south-pointing needle at sea

The famous first use of the compass at sea is a sentence in a Song miscellany, often dated to a work composed between 1111 and 1117 — and published two years after that window closed, in 1119.

What Zhu Yu actually wrote down

No shipboard episode is identifiable in the calendar year 1117. The date belongs to a book: Zhu Yu's Pingzhou Ketan, a Song-dynasty miscellany whose composition is usually assigned to the window 1111–1117.

In its maritime passage, seagoing-ship pilots follow coastal features, steer by the stars at night and the sun by day, and consult a south-pointing needle in overcast or dark weather.

Zhu Yu names no inventor and no particular voyage; the people described are unnamed pilots.

1117, 1119, and which date the record belongs to

1117 is the end of the stated composition window, not a dated first use. The three-volume work was published in 1119, which is why the record is sometimes dated to that year instead.

Either way the passage is evidence that the practice already existed. It is the earliest explicit surviving textual record of a magnetic compass used for maritime navigation, not an account of the compass being invented or used for the first time.

Shen Kuo's earlier account, dated about 1088, describes magnetizing a needle with lodestone and suspending it, but does not explicitly document use aboard ship.

What the passage does not say

The text does not describe how the needle was mounted. Calling Zhu Yu's device a pivoted, suspended or floating compass goes beyond his terse words.

It also does not describe the needle replacing anything. The pilots keep using stars and sun, and turn to the compass when the sky disappears.

A recent scholarly reassessment compares earliest maritime-compass dates of about 1100 in China, 1187 in Europe and 1242 in the Arabic world, and rejects a simple one-way chain of transmission between them.

Sources

Researched 23 Aug 2026 6 sources 2 audit passes, 1 issue open Date disputed

How this was checked

Researched from the web into a fact sheet, rewritten from that sheet, then audited against it by a different model. How the pipeline works →

Date disputed. Sources disagree; the research places it at ~1117.

What the sources leave uncertain

There is no known event that occurred specifically in the calendar year 1117 in which the compass was suddenly used at sea for the first time.
The traditional 1117 date is a bibliographical endpoint assigned to the composition of Pingzhou Ketan, not the date of a named voyage or invention.
Other cataloguing dates place completion or publication in 1119. The safest date is therefore approximate, and the title should say “first recorded,” not “first used.”
The passage does not describe the needle’s mounting. Identifying Zhu Yu’s device specifically as a pivoted, suspended or floating compass goes beyond his quoted words.