Military Records

A History of Naval Deck Logs

View the list of logbooks that are online in the National Archives Catalog:

Through 1940

1941 and later

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 a few 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.

The standard term for these records is deck logs, however, more colloquial terms are sometimes used 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 deck logs were typed, though others were handwritten. This was applied inconsistently, with most logs being handwritten by the mid 1960s. There are a few logs of non-ship units, such as receiving stations or Motor Torpedo Boat squadrons (MTBRONs), but none dating from after 1945.

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. Some of this data is carried over onto the top of each deck log page depending on format and style of deck log in use at a given time.

Deck Logs of commissioned U.S. Navy Ships are held at the National Archives in Washington, DC and at the National Archives in College Park, MD. Generally, Deck Logs dated 1940 and earlier are held at the National Archives in Washington, DC and Deck Logs dated 1941 and later are held at the National Archives in College Park, MD. On rare occasions Deck Logs dated 1940 are held at the National Archives in College Park, MD. This usually occurs if a ship was commissioned in the last quarter of the calendar year of 1940. Conversely, Deck Logs dated 1941 on rare occasions are held at the National Archives in Washington, DC. This usually occurs when a ship was decommissioned in the first quarter of the calendar year of 1941.

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