BNWAS – BRIDGE NAVIGATION WATCH ALARM SYSTEM

BNWAS is a system that monitors the bridge and the Officer of the Watch (OOW) to prevent
mari me accidents. It automa cally alerts the Master or another qualified OOW if the OOW
is unable to perform their du es. BNWAS should be opera onal when the ship is underway
at sea, unless the Master inhibits it.
The purpose of a bridge naviga onal watch alarm system (BNWAS) is to monitor bridge
ac vity and detect operator disability which could lead to marine accidents.
The system monitors the awareness of the Officer of the Watch (OOW) and automa cally
alerts the Master or another qualified OOW if for any reason the OOW becomes incapable
of performing the OOW du es. This purpose is achieved by a series of indica ons and alarms
to alert first the OOW and, if he is not responding, then to alert the Master or another
qualified OOW.
Addi onally, the BNWAS may provide the OOW with a means of calling for immediate
assistance if required.
BNWAS warnings are given in the case of incapacity of the watchkeeping officer due to
accident, sickness or in the event of a security breach, e.g. piracy and/or hijacking. Unless
decided by the Master only, the BNWAS shall always remain opera onal.
There have been many incidents in the past wherein ships have collided or grounded due to
wrong decision or inefficiency in taking a decision at the correct me.

If during an emergency, a naviga onal officer is not capable of handling that situa on, it can
lead to devasta ng scenarios. To avoid this BNWAS is installed on the bridge which acts like a
dead man alarm in the engine room.

A series of alert and alarm is first sounded by BNWAS in the Naviga on Bridge to alert officer
on watch. If there is no response to the series of alarms, then BNWAS will alert other Deck
officers, which may include Master of the ship, so that someone can come out on the bridge
and handle the situa on and tackle the problem.

The BNWAS primarily has three modes of opera on:

 Automa c

 Manual ON

 Manual OFF
Alarms and Indica ons
1. Once the BNWAS is put into opera on, the dormant period should be between 3 to
12 minutes. This dormant period is the me in which the BNWAS is ac ve without
giving any the alarm.
2. Once the dormant period ends, a visual indica on (first stage; flashing indica on) will
be ac vated indica ng/demanding that the officer reset it, if available and ac ve
3. If not reset within 15 seconds of the visual indica on, an audible alarm is sounded
(first stage)
4. If at the first stage the audible alarm is not reset, 15 seconds a er the audible alarm,
another audible alarm (second stage; the sound should have its own characteris c
tone or modula on intended to alert, but not to startle, the OOW) is sounded in the
backup officer’s and/or Master’s cabin
5. If at the second stage the audible alarm is not reset, 90 seconds a er it, another
audible alarm is sounded (third stage; easily recognisable, indicates urgency, a
volume sufficient for it to be heard throughout the loca ons above and to wake
sleeping persons) at the loca ons of further crew members capable of taking
correc ve ac ons
6. Except for passenger vessels, the second and third stage alarm can be combined to
sound at all loca ons. If this is applied, the third stage alarm may be omi ed
7. For very large vessels, sufficient me of up to 3 minutes must be accounted for the
backup officer or the Master to the reach the Bridge to tend to the situa on
The Reset Func on
1. Reset can only be done from physically located areas of the bridge providing proper
look out

2. Reset can be only be done with a single operator ac on (for those familiar with
BNWAS, one stroke to the round reset switch) which starts the dormant period
further, cancelling the alarms/indica ons

3. Constant ac va on of the dormant period vis a vis the reset bu on should not
extend the dormant period to more than that is set or bring about any suppression of
the alarms/indica ons

Addi onally,
1. An “Emergency Call” feature is available to immediately skip to the second and third
stage alarms. This is present for the OOW to summon immediate assistance

2. Accuracy of the BNWAS is within the window of 5% or 5 seconds, whichever is lesser

3. Opera onal Mode and the dura on of the Dormant Period se ng is restricted to the
Master only

4. It is powered from the main power supply. The malfunc on indica on and all
elements of the Emergency Call facility are powered from a ba ery maintained
supply

5. Outputs are available for connec on of addi onal bridge visual indica ons and
audible alarms and remote audible alarms.
All ships of 150 gross tonnage and upwards and passenger ships irrespec ve of size shall, in
addi on to the requirements of paragraph 2.1, be fi ed with a bridge naviga onal watch
alarm system (BNWAS), as follows:

.1 cargo ships of 150 gross tonnage and upwards and passenger ships irrespec ve of size
constructed on or a er 1 July 2011;

.2 passenger ships irrespec ve of size constructed before 1 July 2011, not later than the first
survey* a er 1 July 2012;

.3 cargo ships of 3,000 gross tonnage and upwards constructed before 1 July 2011, not later
than the first survey* a er 1 July 2012;

.4 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* a er 1 July 2013; and

.5 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* a er 1 July 2014.

The bridge naviga onal watch alarm system shall be in opera on whenever the ship is
underway at sea

A bridge naviga onal watch alarm system (BNWAS) installed prior to 1 July 2011 may
subsequently be exempted from full compliance with the standards adopted by the
Organiza on, at the discre on of the Administra on.