Large reel with (later) hand log, circa 1880
Anonymous, Netherlands
Maker:
Collectie:
NavigArte
With the traditional hand log, the ship’s speed was measured using the ‘log chip’ cast astern. The line, knotted at intervals of 14.42 metres, was allowed to run out by hand. When the sailor called ‘stop’ using a sandglass of 28 seconds, the number of knots counted indicated the ship’s speed in ‘knots’ or in ‘nautical miles per hour’ (1.852 km).
Common, English or Hand log as used between 1574 till 1920( 60) The log and line was first described by William Bourne in 1574 and was used for measuring ship’s speed into the 20th century.
This wooden log-reel would originally have carried a line with knots tied at fixed intervals attached to a log-ship, a piece of board in the shape of the segment of a circle with its curved edge weighted. This was used to measure a ship’s speed. To do this, the log-ship was dropped overboard and the line was allowed to pay out from the log reel for a time set by a sand-glass. As the line paid out the number of knots that passed through the hand was counted, thus giving a measure of the ship’s speed in Knots, during each 28 or 14 seconds on sand-glass.