Feature 4 | BRIDGE SYSTEMS
Martek Marine’s Navgard system, which the company is especially hoping to pitch to the retrofit market.
could be interesting to observe whether new technologies come to the fore, allowing for changes in the BNWAS standards, over the course of the decade.
systems”, adding: “The Navgard motion sensors cover everybody within a 10m radius and pick up on movement and body heat. They have been developed to take into account variables such as the air temperature and atmospheric conditions, so they are looking for a particular signature before
they
record a lack of movement and trigger the alarm. “In this way, the sensors wouldn’t pick
up on, say, a bird which has entered the bridge, just as a burglar alarm system won’t typically be triggered by the movements of a domestic pet, because of the differences in body mass.” In other words, there is scant opportunity for personnel to slink off for recreational purposes while leaving a dog or cat on
the bridge in an attempt to ‘trick’ the BNWAS. However, Taylor does raise the valid
point, backed by recent objections from Lloyd’s Register, that, should the OOW be subject a seizure or a fit, the sensors may still detect ‘movement’ of some sort and therefore automatically ‘assess’ that the individual is fine. Similarly, and theoretically at least, a sleeping OOW may only have to twitch his or her arm every few minutes for the sensors to fail to pick up the individual’s ‘immobile’ state, and for the BNWAS to remain in dormant mode. In the absence of any immediate alternatives amid a pressing deadline,
societies have given motion sensor-led verification the nod for now, although it
Alarm cycles Should the sensors on any system detect non-movement on the bridge in the 3-12 minute period (set at intervals of either three, six, nine or 12 minutes), the new BNWAS requirements call for a multi-stage alarm process to swing into action. Upon the first detection of non-movement, a pre-warning visual alarm must be activated at the bridge, requiring the crew to hit the manual reset button to turn it off. Operators can install as many reset buttons as they choose, provided that they are situated either on the bridge or the bridge wings. In accordance with the standards, the pre-warning alert lasts for 15 seconds. If this is not acted on, ‘Stage 1’ of the
the classification
process sounds an audio alarm on the bridge, in order to provoke crew into effecting a manual reset and enabling the BNWAS to return to dormant mode. Failure to respond to this alarm will then initiate ‘Stage 2’, which activates the alarm at selected back-up officers’ cabins. A lack of response at this phase will finally lead to ‘Stage 3’, where the alarm will be made audible at all officers’ locations and communal areas, including crew mess rooms and TV and recreation areas. Tat the crew cannot manually reset the BNWAS from their cabins or locations is intended to ensure that, should an OOW be injured or incapacitated, his or her colleagues are guaranteed to arrive on the
MARINE DISTRESS SIGNALS
48
Ship & Boat International July/August 2011
www.painswessex.com
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