IMO MSC.86 (May 2009) decided to make the BNWAS mandatory for all ships of 150 GT and upwards, engaged in international voyage, and passenger ships irrespective of size, constructed on or after 1 July 2011, also engaged in international voyage, shall be fitted with the BNWAS which shall be in operation when the ship is underway at sea.
Ships constructed prior to 1st July 2011 will have to retrofit the BNWAS by the 1st survey after that date.
The purpose of BNWAS (Bridge Navigational Watch Alarm System) is to monitor bridge activity and detect operator disability which could lead to marine accidents.
BNWAS monitors the watch officer’s presence through watch safety system functions.
A watch officer is required to press the button on a Timer Reset Panel or to operate navigation equipment (e.g. ECDIS, Radar, etc.) at certain intervals.
When the officer fails to press the button within pre-set intervals, visual and audible alarms will be generated in the wheelhouse.
If the officer doesn’t respond to the alarm, the system transfers the alarm to the Cabin Panels installed in other sections of the vessel in order to inform backup officers of the watch officer’s incapacity.
The timer reset may be facilitated by one of following means:
It is important to keep in mind when planning a BNWAS installation that the external devises, which can act as reset devises, need to be located in position where proper lookout can be done by the watch officer.
For the motion sensor, it is critical to locate it in such a way that it cannot be activated by the ships movements. Thus, any curtains present on the bridge deck should not come in the way of the sensor.
For first line of alert, in accordance with IMO Res. MSC.128(75), sufficient number of visual indications (flashing lights) are to be installed and connected.
The visual indications should be visible from all operational positions within the bridge where the OOW (Officer of the Watch) may be stationed to perform his duties.
These positions are made up by, but not limited to, Conning work station, Navigation support work station, steering work station and 2 x docking work stations.
BNWAS should incorporate the following 3 operational modes:
For use of languages other than English, please consult with the flag administration and/or class society concerned, before operating BNWAS in those languages.
1. The watch officer in the wheelhouse has to press the button on Timer Reset Panel or operate interfaced equipment at certain intervals. (Dormant period, 3-12 min.)
2. If the watch officer does not press the button on Timer Reset Panel or operate interfaced equipment, the Main Alarm Panel, the Timer Reset Panel and the Flash Beacon (optional) generate the visual alarm in 15 seconds. (Prewarning)
3. If the visual alarm is not acknowledged in the prewarning period, the Main Alarm Panel and the Timer Reset Panel generate the audible alarms as well as visual alarm in 15 seconds. (1st Stage)
4. If the officer doesn't respond to the alarm in the 1st Stage, the BR-500 transmits the alarm to the selected Cabin Panels in the selected back-up officer's and/or the captain's room as well as the cabin panels in pubic rooms. (2nd Stage)
5. If the alarm is not acknowledged within the pre-set time, the system transmits the alarm to all Cabin Panels. (3rd Stage)
6. The buzzer stops when the officer presses the [RESET] button. The Main Alarm Panel will reset the timer and return to the dormant period, when the alarm is acknowledged by the watch officer.