Chip log
instrument used to measure the speed of a ship at sea

A chip log, also called common log, ship log, or just log, is a navigation tool mariners use to estimate the speed of a vessel through water. The word knot, to mean nautical mile per hour, derives from this measurement method.
History
All nautical instruments that measure the speed of a ship through water are known as logs. This nomenclature dates back to the days of sail, when sailors attached a piece of lumber (a "log" of wood) to a rope knotted at regular intervals off the stern of a ship. Sailors counted the number of knots that passed through their hands in a given time to determine the ship's speed. Modern sailors and aircraft pilots still express speed in knots.
Construction
A chip log consists of a wooden board attached to a line (the log-line). The log-line has a number of knots at uniform intervals. The log-line is wound on a reel so the user can easily pay it out.
Over time, log construction standardized.
This brief starts where responsible research should: with the source description of “Chip log” as instrument used to measure the speed of a ship at sea. Everything that follows is an evidence route, not borrowed authority.
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The subject matters to the places & architecture register because the source frames it as instrument used to measure the speed of a ship at sea. Its deeper value depends on whether names, dates, institutions and citations support that framing.
Maps, plans, fabric surveys and administrative records can establish how the site’s name, extent and function changed over time. The source revision retrieved here is dated Jul 18, 2026. The linked authority identifier is Q638004. None of the 0 selected statements returned an explicit reference.
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This entry incorporates text from “Chip log” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.