Purpose of BNWAS:-
- The purpose of a bridge navigational watch alarm system is to monitor bridge activity and detect operator disability which could lead to marine accidents.
- The system monitors awareness of the Officer of the Watch (OOW) and automatically alerts the Master or another qualified person if, for any reason, the OOW becomes incapable of performing OOW duties.
- This purpose is achieved by series of indications and alarm to alert first the OOW and, if he is not responding, then to alert Master or another qualified person.
- Additionally, the BNWAS provides the OOW with means of calling for immediate assistance if required.
Operational Modes of BNWAS:-
BNWAS should incorporate the following 3 operational modes:
- Manual ‘ON’
- Manual ‘OFF’
- Automatic: The BNWAS is automatically activated when the vessel is navigating by means of heading or track control system (autopilot / trackpilot) and inhibited when this system is deactivated.
- Manual ON: The BNWAS is always in operation.
- Authorized person (Master) switches on system by single turning the key-switch to position “ON/OFF”.
- Once dormant period (3 min, 9 min, 12 min) is set, the authorized person pulls out the key.
- Dormant period starts from the moment the system has been switched on.
- Manual OFF: The BNWAS is turned off completely.
ALERT SEQUENCE: – If dormant period is over without the OOW resetting, the system activates all reset units by flash light.
ALERT STAGE 1:- If dormant period and flash light period (15 sec) are over and the OOW has not yet resetted the button, the system activates electronic buzzer on terminal board as well as additional buzzers located on the bridge and wing area.
ALERT STAGE 2:- If dormant period, flash light period (15 sec) and alert stage 1 (15 sec) are over without OOW’s reset, system activates further alert via optic / acoustic alarm devices in officer’s area (cabins or staircase) as well as for VDR link.
ALERT STAGE 3:- If dormant period, flash light period (15 sec), alert stage 1 (15 sec) and alert stage 2 (90 sec) are over without OOW’s reset, the system activates the General Alarm as well as for VDR link.
- The OOW generates an emergency call by pushing any reset unit longer than 5 sec.
- That immediately activates alert stage 2 and subsequently alarm stage 3.
- After emergency call has been released, reset is possible by pushing a reset unit.
Requirements of BNWAS:-
- The bridge navigational watch alarm system shall be in operation whenever the ship is underway at sea.
- System is powered by ships main power and MUST have a battery back up giving a minimum of 6 hours usage.
Carriage Requirements of Bridge Navigational Watch Alarm System (BNWAS):-
- Cargo ships of 150 grt and upwards and passenger ships irrespective of size constructed on or after 1 July 2011;
- Passenger ships irrespective of size constructed before 1 July 2011, not later than the first survey after 1 July 2012;
- Cargo ships of 3000 grt and upwards constructed before 1 July 2011, not later than the first survey after 1 July 2012;
- Cargo ships of 500 grt and upwards but less than 3000 grt constructed before 1 July 2011, not later than the first survey after 1 July 2013; and
- Cargo ships of 150 grt and upwards but less than 500 grt constructed before 1 July 2011, not later than the first survey after 1 July 2014.