What is BNWAS, its Performance & Carriage Requirements?

BNWAS
Written by Amit Sharma
What is BNWAS (Bridge Navigational Watch Alarm System)?

A Bridge Navigational Watch Alarm System,( BNWAS) , is an automatic system which sounds an alarm if the watch officer on the bridge of a ship falls asleep, becomes otherwise incapacitated, or is absent for too long a time. The BNWAS is automatically engaged when the ship’s autopilot is activated.

The bridge navigational watch alarm system shall be in operation whenever the ship is underway at sea; 

Bridge Navigational Watch & Alarm System – BNWAS is a monitoring and Alarm system which notify other navigational officers or master of the ship if the officer on watch (OOW) does not responds or he/she is incapable of  performing the watch duties efficiently which can lead to maritime accidents.

The minimum requirement for a BNWAS under International Maritime Organization standards is to have a dormant stage and three alarm stages, except that on a non-passenger vessel, the second stage may be omitted. 

Stage 1: When the autopilot is engaged, the bridge officer is required to signal his presence to the BNWAS system every 3 to 12 minutes in response to a flashing light, either by moving an arm in front of a motion sensor, pressing a confirmation button, or directly applying pressure to the BNWAS centre.

Stage 2: When a confirmation signal fails to occur within 15 seconds in Stage 1, an alarm will sound on the bridge, and if there is still no confirmation signal after a further 15 seconds, in the captain’s and the first officer’s cabins. One of them must then go to the bridge and cancel the alarm.

Stage 3: If neither the captain nor the first officer cancels the alarm within a specified time period (between 90 seconds and 3 minutes depending on the size of the vessel), an alarm will sound in locations where other personnel are usually available.

What is the need of  BNWAS?

“The purpose of the bridge navigational watch alarm system (BNWAS) is to monitor bridge activity and detect operator disability which could lead to marine accidents. The system monitors the awareness of the Officer of the Watch (OOW) and automatically alerts the Master or another qualified OOW if for any reason the OOW becomes incapable of performing the OOW’s duties.

This purpose is achieved by a series of indications and alarms to alert first the OOW and, if he is not responding, then to alert the Master or another qualified OOW. Additionally, the BNWAS may provide the OOW with a means of calling for immediate assistance if required.

The BNWAS should be operational whenever the ship’s heading or track control system is engaged, unless inhibited by the Master.”

What is Carriage requirements of BNWAS as per SOLAS?

The requirements making it mandatory to have a bridge navigational watch alarm system (BNWAS) fitted to all passenger and cargo vessels can be found in the amendments made to SOLAS Chapter V Regulation 19 that were adopted by the IMO. 

  • cargo ships of 150 gross tonnage and upwards and passenger ships of any size constructed on or after 1 July 2011;
  • passenger ships of any size constructed before 1 July 2011, not later than the first survey after 1 July 2012;
  • cargo ships of 3,000 gross tonnage and upwards constructed before 1 July 2011, not later than the first survey after 1 July 2012;
  • cargo ships of 500 gross tonnage and upwards but less than 3,000 gross tonnage constructed before 1 July 2011, not later than the first survey after 1 July 2013; and
  • cargo ships of 150 gross tonnage and upwards but less than 500 gross tonnage constructed before 1 July 2011, not later than the first survey after 1 July 2014.

The new Resolution MSC.350(92) now clarifies in SOLAS V, Reg.19.1.2.4, the implementation schedule for the carriage of BNWAS for ships constructed before 1 July 2002 as follows:

  • passenger ships irrespective of size, not later than the first survey after 1 January 2016;
  • cargo ships of 3,000 gross tonnage and upwards, not later than the first survey after 1 January 2016;
  • cargo ships of 500 gross tonnage and upwards but less than 3,000 gross tonnage, not later than the first survey after 1 January 2017; and
  • cargo ships of 150 gross tonnage and upwards but less than 500 gross tonnage, not later than the first survey after 1 January 2018.

July 2011: new vessels in excess of 150 tonnes

July 2011: all passenger vessels

July 2012: all vessels in excess of 3,000 tonnes

July 2013: all vessels between 500 and 3,000 tonnes

July 2014: all vessels between 150 and 500 tonnes

The bridge navigational watch alarm system shall be in operation whenever the ship is underway at sea.

Is it necessary to connect the BNWAS to the VDR?

According to the Code on Alerts and Indicators, Resolution A.1021(26), implemented on 18 January 2010, the BNWAS first-stage audible alarm and the malfunction of, or power supply failure to, the BNWAS are classified as a mandatory alarm. The BNWAS should be connected to the VDR on ships whose keel is laid on or after 18 January 2010.

What is IMO  performance standard requirements  for BNWAS?

IMO performance standard for BNWAS are as follows:

Operational modes

The BNWAS shall incorporate the following operational modes:

  • Automatic (Automatically brought into operation whenever the ship’s heading or track control system is activated and inhibited when this system is not activated)
  • Manual ON (In operation constantly)
  • Manual OFF (Does not operate under any circumstances)
  • Operational sequence of indications and alarms

Dormant period

Once operational, the alarm system shall remain dormant for a period of between 3 and 12 min (Td). At the end of this dormant period, the alarm system shall initiate a visual indication on the bridge.

bnwas 1

Figure:   Alarm  Sequence Without  Acknowledgements.

First stage alarm

If not reset, the BNWAS shall additionally sound a first stage audible alarm on the bridge 15 s after the visual indication is initiated.

Second stage alarm

If not reset, the BNWAS shall additionally sound a second stage remote audible alarm in the back-up officer’s and/or Master’s location 15 s after the first stage audible alarm is initiated.

Third stage alarm

If not reset, the BNWAS shall additionally sound a third stage remote audible alarm at the locations of further crew members capable of taking corrective actions 90 s after the second stage remote audible alarm is initiated.

Alarm alternatives

In vessels other than passenger vessels, the second or third stage remote audible alarms may sound in all the above locations at the same time. If the second stage audible alarm is sounded in this way, the third stage alarm may be omitted.

In larger vessels, the delay between the second and third stage alarms may be set to a longer value on installation, up to a maximum of 3 min, to allow sufficient time for the back-up officer and/or Master to reach the bridge.

Facilities shall be provided to inhibit the third stage alarm and to increase the delay between the second and third stage alarms to 3 min.

Reset function

The reset function shall, by a single operator action, cancel the visual indication and all audible alarms and initiate a further dormant period. If the reset function is activated before the end of the dormant period, the period shall be re-initiated to run for its full duration from the time of the reset.

Initiation of reset function

To initiate the reset function, an input representing a single operator action by the 00W is required. This input may be generated by reset devices forming an integral part of the BNWAS or by external inputs from other equipment capable of registering physical activity and mental alertness of the 00W.

Continuous activation

A continuous activation of any reset device shall not prolong the dormant period or cause a suppression of the sequence of indications and alarms.

Emergency call facility

Means may be provided on the bridge to immediately activate the second, and subsequently third, stage remote audible alarms by means of an “Emergency Call” push button or similar.

Facilities shall be provided for an “Emergency Call” system.

Accuracy

The alarm system shall be capable of achieving the timings stated in above paragraph  with an accuracy of 5% or 5 s, whichever is less, under all environmental conditions.

Security

The means of selecting the Operational Mode and the duration of the Dormant Period (Td) shall be security protected so that access to these controls should be restricted to the Master only.

Malfunctions, alarms and indications

If a malfunction of, or power supply failure to, the BNWAS is detected, this shall be indicated. Means shall be provided to allow the repeat of this indication on a central alarm panel if fitted.

About the author

Amit Sharma

Graduated from M.E.R.I. Mumbai (Mumbai University), After a brief sailing founded this website with the idea to bring the maritime education online which must be free and available for all at all times and to find basic solutions that are of extreme importance to a seafarer by our innovative ideas.