Log (Log-Book)

The log board was a large sheet of paper, divided into columns for recording wind direction, weather conditions, the ship's course and speed. Officers in charge of each watch also recorded events they thought important on the log-board.

Usually each of the principal officers on board a man of war of East India vessel kept a journal, into which they would copy information from the log board.

Vessels ran on what was known as 'ship's time'. Each day began twelve hours earlier than on land, and ended at noon the following day, not midnight. The day was divided into four watches. At noon on the end of each day, the contents of the log-board were transferred to the log-book, and signed by the vessel's commanding officer.

The name log-book came about because the principal instrument used for measuring the ship's speed at sea was called a log, or log-line. This device was actually a small crafted piece of timber or wooden board, usually balanced with a piece of lead, and attached to a line and reel.

On how the log was used to measure distance, see the entry for log in the South Seas Project's on-line edition of William Falconer's Dictionary of the Marine.

• Falconer, William, Online edition of William Falconer's Universal Dictionary of the Marine, or, a Copious Explanation of the Technical Terms and Phrases employed in the Construction, ...of a Ship...derived from the text of the London 1780 edition published by Thomas Cadell, 2004 edn, South Seas, http://paulturnbull.org/projects/southseas/refs/falc/contents.html. [ Details ]