Military Records

A History of Naval Deck Logs

In Navy parlance, any kind of running record is called a "log." Many such logs are kept on board Navy ships, but only deck logs of commissioned Navy ships are retained permanently. A commissioned ship is a Navy command in her own right, having a distinctive administrative identity and creating records in her own name. Most service vessels (such as harbor tugs, landing craft, or launches) are classified as "in service" instead of "in commission" and do not possess their own administrative identity. Instead, they report through a higher-echelon parent command. While "in service" vessels may produce logs that are submitted to their parent command, those logs are not retained as permanent records. (The World War II era is a partial exception to that rule. Note, however, that there are logs for only 3 of the 1,465 LCTs [Landing Craft, Tank] constructed during the war.)

Deck logs were created to form a chronological account of notable events occurring in and around a ship (or other command, as appropriate), to serve as a reminder to the officers of the deck of their various duties, and to serve as a check on the activities of the officers of the deck. They were also maintained to serve as potential evidence in legal proceedings in naval, admiralty, or civil courts.

These records are often referred to as deck logs, or by more colloquial terms, such as ship logs, captain's logs, smooth logs, or rough logs. Deck logs are not daily diaries written by ship captains or other officers. Therefore, the common term "captain's log" is a misnomer. The term has never been applied to logs created in the US Navy (although the British Royal Navy did use the term at one time).

Deck logs consist of chronological entries documenting the daily activities of a commissioned Navy ship, unit, station, or other command. Individual logbooks are arranged chronologically by date, with entries in each day's log arranged chronologically by the time of day as indicated on the 24-hour clock. Information contained in the logs was often generated from the quartermaster's notebook, also known colloquially as the rough log.

During the 1940s, 1950s, and early 1960s, many logbooks were typed, though others were handwritten (logbooks of most large vessels being typed); beginning in the early 1960s most logs were handwritten. There are a few logs of non-ship units, such as receiving stations or Motor Torpedo Boat squadrons (MTBRONs), but none dating from after 1942.

A deck log's title page, which precedes all entries for a given month, contains spaces to enter the name and/or hull number of the vessel; the name of the commander; the division, squadron, flotilla, or fleet to which that particular ship was attached; the beginning and ending dates of that particular log; and sometimes where the ship was located on those dates. However, title pages often are incomplete.

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