Pin compass
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A traverse board , also plug or cutlery compass , waking or Dutch board called, was a tool for dead reckoning in the earlier sailing ships.
It consisted of a board with the cardinal points, similar to the wind rose on a compass , and holes in eight concentric circles. The eight circles correspond to the eight glasses , i.e. four hours, of the watch at the wheel. Every half hour (= 1 glass) the helmsman put a small stake ('embroidery') into the hole on the pin compass, which corresponds to the course that was held during this time.
In addition, the speed - measured with a log - was recorded in a field below the compass rose, which was driven during the corresponding glass. At the end of the watch, the overall course traveled could be reconstructed and transferred to a nautical chart.
Web links
- Navigation instrument, pin compass . In: Catalog of the scientific collections of the Humboldt University in Berlin , accessed on January 12, 2012