Bridge Navigational Watch Alarm System (BNWAS): A Comprehensive Guide
Bridge Navigational Watch Alarm System (BNWAS) is an automated system designed to enhance maritime safety by monitoring the alertness of the Officer on Watch (OOW) and ensuring timely intervention if the OOW becomes incapacitated. This guide provides a detailed overview of BNWAS, including its history, functionality, stages of alarms, operational requirements, maintenance, and testing.
History of BNWAS
The concept of BNWAS was introduced by the International Maritime Organization (IMO) to address the risks associated with the incapacitation of the OOW. The IMO adopted performance standards for BNWAS in 2002, and the system became mandatory for new ships over 150 gross tonnage from July 2011. The BNWAS was designed to prevent accidents caused by the OOW falling asleep, becoming incapacitated, or being absent from the bridge for too long.
Functionality of BNWAS
BNWAS monitors the activity on the bridge and detects any signs of the OOW's incapacity. The system operates in several stages:
- Dormant Stage: When the ship's autopilot is engaged, the OOW must signal their presence to the BNWAS system every 3 to 12 minutes by moving an arm in front of a motion sensor, pressing a confirmation button, or applying pressure to the BNWAS center.
- Stage 1: If the OOW fails to signal their presence within the set interval, an alarm sounds on the bridge after 15 seconds.
- Stage 2: If there is still no response after another 15 seconds, the alarm is extended to the captain's and first officer's cabins.
- Stage 3: If neither the captain nor the first officer cancels the alarm within a specified time period (90 seconds to 3 minutes), an alarm sounds in locations where other personnel are usually available.
These stages ensure that any incapacity of the OOW is promptly detected, and appropriate action is taken to maintain navigational safety.
Operational Requirements
BNWAS must be operational whenever the ship is underway at sea. The system has three modes of operation: Automatic, Manual ON, and Manual OFF. The dormant period, during which the system is active without sounding an alarm, is between 3 to 12 minutes. The system must be tested regularly to ensure it is functioning correctly.
Maintenance of BNWAS
Regular maintenance of BNWAS is essential to ensure its reliability and effectiveness. Maintenance activities include:
- Routine Inspections: Regular checks of the system's sensors, alarms, and indicators to ensure they are in good working condition.
- Software Updates: Keeping the BNWAS software up-to-date to benefit from the latest features and improvements.
- Battery Checks: Ensuring that the backup batteries are fully charged and capable of powering the system in case of a main power failure.
- Record Keeping: Maintaining a log of all maintenance activities, including test results and any repairs or replacements made.
Testing of BNWAS
Testing of BNWAS involves verifying that the system meets the performance standards set by the IMO. This includes:
- Type Approval Testing: Conducted to ensure the BNWAS complies with the IEC 61174 standard for BNWAS.
- Integration Testing: Checking the integration of the BNWAS with other navigational equipment to ensure seamless data collection and recording.
- Functional Testing: Regularly conducting functional tests to ensure the system's alarms and indicators are working correctly and that the OOW's presence is accurately detected.
Conclusion
BNWAS is a critical safety system that enhances maritime
safety by ensuring the alertness of the OOW and providing timely intervention
in case of incapacitation. Regular maintenance and testing are essential to
ensure the system's reliability and effectiveness. By understanding the
history, functionality, stages of alarms, operational requirements,
maintenance, and testing of BNWAS, mariners can ensure they are well-prepared
to handle any incidents at sea.