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Bridge Navigational Watch and Alarm System (BNWAS) is a monitoring and alarm system that alerts other navigational officers or the ship’s Master if the Officer on the watch (OOW) fails to respond or is incapable of performing watch duties effectively, resulting in maritime accidents.

Bridge Navigational Watch and Alarm System

The system checks the Officer of the Watch (OOW) and immediately warns the Master or another qualified OOW if the OOW becomes incapable of fulfilling their duties. It’s accomplished through alerts and indicators that warn backup OOWs and the Master.

In the event of the watchkeeping officer’s incapacity due to an accident, illness, or a security violation, such as piracy and hijacking, BNWAS alerts are issued. Unless the Master decides otherwise, the BNWAS must be functioning at all times.

Why Do Ships Require Bridge Navigational Watch and Alarm System?

There have been numerous situations where ships collided or grounded due to poor decision-making or inefficiency in making a timely decision.

If a navigational officer cannot address an emergency, it can result in disastrous consequences. To avert this, the bridge has a BNWAS system, which works similarly to a dead man alarm in the engine room.

BNWAS sounds a succession of alerts and alarms in the Navigation Bridge to inform officers on duty. If the series of alarms receive no response, BNWAS will notify other Deck officers, So that someone can arrive on the bridge and deal with the situation and solve the problem with the Master of the ship.

BNWAS sounds a succession of alerts and alarms in the Navigation Bridge to inform officers on duty. Suppose the series of alarms receive no response. In that case, BNWAS will notify other Deck officers, including the Master of the ship, so that somebody can arrive on the bridge, deal with the situation, and solve the problem.

BNWAS Operational Requirements

The BNWAS has three main modes of operation:

    • Manual ON

    • Manual OFF

    • Automatic

The Function of Reset

  • Only physically placed portions of the bridge can be reset, ensuring sufficient visibility.
  • Only a single operator action (for those acquainted with BNWAS, one stroke to the round reset switch) can be used to reset the system, which extends the inactive period and cancels the alarms/indications.
  • Constant activation of the latent period in relation to the reset button should not extend the dormant period beyond what is configured or cause the alarms/indications to be suppressed.


  • To skip directly to the second and third-stage alarms, an “Emergency Call” function must be present. This is where the OOW can call for help right away.
  • The BNWAS’ accuracy should be within a 5 percent or 5-second window, whichever is less. Operational Mode and the Dormant Period setting should be limited to the Master alone. All aspects of the Emergency Call facility, including the fault indicator, should be powered by a battery.
  • If necessary, outputs should be compatible with other bridge equipment.

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