Bridge navigational watch alarm system

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A Bridge Navigational Watch Alarm System, abbreviated 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.[1]

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.[2]

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,[3] 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.[2] 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.[2]

In addition an emergency call function may be provided, by which bridge personnel can activate a Stage 2 or Stage 3 alarm to call for help.[4]

IMO requirements under the SOLAS resulting from an amendment of June 5, 2009,[5][6][7] come into force on the following dates for ships classified by size:

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

Specific nations have added further regulations. For example, vessels of the Norwegian coastal fishery are required to activate a speed sensor connected to the vessel's motor or GPS.

Wired and wireless versions are available.


  1. ^ Maritime Safety Committee, International Maritime Organization, Resolution MSC.128(75) (Adopted on 20 May 2002): Performance Standards for a Bridge Navigational Watch Alarm System, MSC 75/24/Add.1 (pdf) p. 2.
  2. ^ a b c Maritime Safety Committee, p. 3.
  3. ^ Maritime Safety Committee, pp. 3, 5.
  4. ^ Maritime Safety Committee, p. 4.
  5. ^ USA. Furuno BR500 delivers BNWAS solution, BYM Marine & Maritime News, 20 December 2011.
  6. ^ IMO: Sub-Committee on Safety of Navigation, Report of the 54th Session, London, June 30 to July 4, 2008 1 at The Daily Telegraph, 4 February 2011.
  7. ^ "Piracy: IMO panel still gun-shy", Marine Log, 18 June 2009.