BRIDGE NAVIGATIONAL WATCH ALARM SYSTEM
(BNWAS)
PURPOSE:
• To monitor bridge activity and detect operators disability which
could lead to marine accident.
• To monitor presence of the OOW and automatically alert the
Master or other qualified Officer if for any reason the OOW
becomes incapable of performing his duties.
WORKING:
• BNWAS achieves its objectives 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 officer.
• Additionally, the BNWAS may provide the OOW with a means of
calling for immediate assistance if required.
SOLAS requirement:
• BNWAS is a safety system that is made mandatory by SOLAS
V/19 for all passenger ships and cargo ships of 150 GT and above.
• BNWAS should be in operation whenever the ship is underway at sea.
(All other characteristics of BNWAS are covered in the required
Performance Standards as described below)
PERFORMANCE STANDARDS
RESOLUTION MSC.128(75) (adopted on 20 May 2002) PERFORMANCE
STANDARDS FOR A BRIDGE NAVIGATIONAL WATCH ALARM SYSTEM
(BNWAS)
1. Operational modes
The BNWAS should incorporate the following operational modes: -
A) Automatic (Automatically brought into operation whenever the
ship’s heading or track control system is activated and inhibited
when this system is not activated)
B) Manual ON (In operation constantly)
C) Manual OFF (Does not operate under any circumstances)
2. Operational sequence of indications and alarms
• Once operational, the alarm system should remain dormant for
a period of between 3 and 12 min.
• At the end of this dormant period, the alarm system should
initiate a visual indication on the bridge.
• If not reset, the BNWAS should additionally sound a first stage
audible alarm on the bridge 15 s after the visual indication is
initiated.
• If not reset, the BNWAS should 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.
• If not reset, the BNWAS should 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.
• 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.
3. Reset function
• It should not be possible to initiate the reset function or cancel
any audible alarm from any device, equipment or system not
physically located in areas of the bridge providing proper look
out.
• The reset function should, 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 should be re-initiated to run
for its full duration from the time of the reset.
• The reset function should be by a single operator action. The
reset function may be by use of reset devices that are part of
the Main BNWAS panel or by external inputs from other
equipment capable of registering physical activity and mental
alertness of the OOW.
• A continuous activation of any reset device should not prolong
the dormant period or cause a suppression of the sequence of
indications and alarms.
• Means of activating the reset function should only be available
in positions on the bridge giving proper look out and preferably
adjacent to visual indications. Means of activating the reset
function should be easily accessible from the conning position,
manoeuvring position, look out positions and bridge wings.
• Reset devices - should be designed and installed so as to
minimise the possibility of their operation by any means other
than activation by the OOW. Reset devices should all be of a
uniform design and should be illuminated for identification at
night.
4. 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.
5. Accuracy
• The alarm system should be capable of achieving the required
timings with an accuracy of 5% or 5 s, whichever is less, under all
environmental conditions.
6. Security
• The means of selecting the Operational Mode and the duration
of the Dormant Period should be security protected so that
access to these controls should be restricted to the Master only.
7. Malfunctions
• If a malfunction is detected or power supply failure to the
BNWAS is detected, this should be indicated. This indication
should be repeated on a central alarm panel if fitted.
8. Presentation of Information, Alarms and indications
• Operational Mode - The operational mode of the equipment
should be indicated to the OOW.
• Visual indications - The visual indication initiated at the end of
the dormant period should be a flashing indication, that is visible
from all operational positions on the bridge where the OOW
may reasonably be expected to be stationed. The colour of the
indication should be chosen so as not to impair night vision and
dimming facilities (although not to extinction) should be
incorporated.
• First stage bridge audible alarm - The first stage audible alarm
which sounds on the bridge at the end of the visual indication
period (15s) should have its own characteristic tone or
modulation intended to alert, but not to startle, the OOW. This
alarm should be audible from all operational positions on the
bridge where the OOW may reasonably be expected to be
stationed. It may sound from one or more sounding devices.
Tone/modulation characteristics and volume level should be
selectable during commissioning of the system.
• Second and third stage remote audible alarm - The remote
audible alarm which sounds in the locations of the Master,
officers and further crew members capable of taking corrective
action at the end of the bridge audible alarm period should be
easily identifiable by its sound and should indicate urgency. The
volume of this alarm should be sufficient for it to be heard
throughout the locations above and to wake sleeping persons.
9. System physical integrity
• All items of equipment forming part of the BNWAS should be
tamper-proof so that no member of the crew may interfere with
the systems operation.
10. Power supply
• The BNWAS should be powered from the ships main power
supply. The malfunction indication, and all elements of the
Emergency Call facility, if incorporated, should be powered from
a battery maintained supply.
Implementation Schedule
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.
