The Officer of the Watch (OOW) bears full responsibility for the safe navigation of the vessel during their watch period. Under STCW (Standards of Training, Certification and Watchkeeping for Seafarers), specific competences are required of every deck officer standing a navigational watch, including proficiency in collision avoidance, position monitoring, and meteorological observation.
Core OOW duties
- Maintain a proper lookout — visual, radar, AIS, and sound (COLREGS Rule 5)
- Monitor the vessel's position — fix at regular intervals appropriate to the proximity of hazards
- Assess all vessels for collision risk — plot radar contacts, calculate CPA/TCPA
- Apply COLREGS — take the correct action as give-way or stand-on vessel
- Call the Master — whenever in doubt, when visibility deteriorates, or when approaching congested traffic
- Record — maintain the deck log and record events and position fixes
STCW rest hour requirements
Fatigue is the single largest contributing factor in maritime casualties. STCW mandates minimum rest periods: at least 10 hours rest in any 24-hour period, and at least 77 hours in any 7-day period. No officer should stand a watch in a fatigued state, and the master must not order a watch that would violate STCW rest requirements.
32 free maritime games — no account needed
Binnacle AI Arcade has games for every aspect of seamanship, from cargo stowage to COLREGS to heavy weather. Free to play, global leaderboards, daily challenges.
Browse all games ▸
Frequently asked questions
What certificates are required to stand a navigational watch?
Under STCW, a STCW II/1 Certificate of Competency (Officer in Charge of a Navigational Watch) is required for officers on vessels over 500 GT. This requires specific sea service, approved training, and passing STCW assessments.
When should the OOW call the Master?
The OOW should call the Master if in doubt about any aspect of navigation, when visibility is restricted, when traffic density requires close attention, when approaching a difficult anchorage or port, or when equipment fails.
What is the 20/20 rule for fatigue?
The 20/20 rule is an industry guideline: an officer who has slept fewer than 5 hours in the past 24 hours or fewer than 20 hours in the past 48 hours is considered impaired to a degree comparable to a blood-alcohol level above the legal limit.
What is a navigation brief?
A navigation brief is the master's briefing to the watch officer before a critical passage — narrow channel, traffic separation scheme, port approach — covering the passage plan, critical hazards, special instructions, and call criteria.