The duty officer is the officer currently on watch. During their watch, they are responsible for the ship, installation, or unit — they exercise the captain’s authority within defined limits and answer for everything that happens.

Watches rotate on a fixed schedule. A typical naval watch is four hours: 0000–0400, 0400–0800, 0800–1200, and so on. The duty officer on the midnight watch has the same authority as the duty officer on the noon watch. The authority belongs to the position, not the person. When the watch ends, authority transfers to the next duty officer.

The handoff is formal. The outgoing officer briefs the incoming officer on the current situation — weather, vessel status, active orders, anything unusual. Both officers must agree the transfer has happened. Until that agreement, the outgoing officer retains authority. If a crisis is in progress, the handoff waits — you do not change watch in the middle of an emergency.

The duty officer keeps a log. Every significant event during the watch is recorded — course changes, contacts, orders received, incidents. The duty officer signs the log at the end of the watch. The log is an official document and the permanent record of what happened and who was responsible.

Standing orders from the captain define what the duty officer can and cannot do without calling for help. “Call the captain if visibility drops below one mile.” “Do not alter course without permission.” The duty officer executes within these bounds. Anything outside them requires waking someone up.

The duty officer is the captain’s authority operating in shifts. The captain cannot be awake 24 hours a day, so command is exercised through a rotation of officers who each take full responsibility for their slice of time. The captain remains ultimately accountable, but during the watch, the duty officer IS the exercise of command.

The key distinction: a duty officer has assumed the watch. An on-call officer has not — they are available but not actively in charge. A staff officer advises but does not command. The duty officer commands.