Deck Log

The deck log — also known as the official log book — is the primary contemporaneous record of a vessel's voyage, maintained on the bridge by the officer of the watch or as directed by the master. It records the ship's position at regular intervals, course and speed, weather conditions, watch handovers, drills, crew incidents, security events, and any incidents affecting the vessel or persons on board. The deck log is a legal document: entries must be made in ink, contemporaneously, and must not be altered. For an officer of the watch, the log is part of the duty. Completing the log accurately at each watch — recording compass bearings, engine status, voyage notes, and any significant events — is not merely a bureaucratic task but creates the official narrative of the voyage. In the event of a collision, grounding, or injury, the log will be one of the first documents requested by investigators, insurers, flag state surveyors, and lawyers. Port state control inspectors review the deck log for evidence of drills, rest hour compliance, and incidents. An absence of drill records, gaps in position entries, or entries made in pencil or with visible alterations are red flags. The log must be kept on board for the period prescribed by the flag state, typically several years. Masters are responsible for ensuring that all officers understand their logging obligations and that the log accurately reflects events on board.