Chip Log

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£80.00

A chip log consists of a wooden board attached to a line (the log-line). The log-line has a number of knots tied in it at uniform spacings. The log-line is wound on a reel to allow it to be paid out easily in use.

When the navigator wished to determine the speed of his vessel, a sailor dropped the log over the stern of the ship. The log would act as a drogue and remain roughly in place while the vessel moved away. The log-line was allowed to run out for a fixed period of time. The speed of the ship was indicated by the length of log-line passing over the stern during that time.

The log has been used by mariners for a long time. The first occurrence of a description of the device in print was in A Regiment for the Sea by William Bourne in 1574.

Initially, the log-line was not knotted and the length was measured directly on the line. With the introduction of the nautical mile as a standard unit of measure at sea in the 15th century, the line began to be marked at equal intervals proportional to the nautical mile and to the time interval used for measurement. Initially, the markings were in the form of knots in the line. Later, knotted cords were worked into the log-line.

Our Chip Log consists of a reel that is 23" long by 5" high and a log that is 10" wide by 10" high. They are made from 3/4" thick hardwood treated with linseed oil. The log-line is period correct hemp rope with knots tied in it at the correct distances.