The Art of Dredging

Dredging and shipping


Ships have been running aground on the Great Barrier Reef ever since captain James Cook set the example.

On April 3rdh, 2011, bulkcarrier "Shen Neng 1" hit a coral reef off the Australian west coast.

In its final report, the Australian Transport Safety Bureau put forward that the chief mate was fatigued, affecting his performance as Officer of the Watch (OOW).

"Fatigue is one of the key safety risks facing seafarers, and watchkeepers in particular."

The ATSB urged ship operators to comply with international requirements and properly manage the hours of work and rest of watchkeepers.

The report stated that a succession of quite simple and small errors on the part of a tired crew led to the ship's grounding.

The problem of fatigue onboard is closely connected with the concept of "safe manning".

The flagstate of a ship decides what is the minimal safe manning of a ship, based on IMO resolution A.890(21).

Normally, these IMO resolution sets out high standards, but flagstates do not follow this IMO-resolution, since they are only "recommendations", leading to very low "safe manning" crew numbers on ship's"safe manning" certificates.

An example: Panama-flagged VLCC's may sail with a captain and two mates, and that's perfectly legal. 

Serious shipping companies make their own assesment of necessary crew levels onboard; but other companies just go with the (deflated) crew numbers on the "safe manning certificate".

Only recently, Port State Control officials (Paris MOU) have been writing deficiencies against low "safe manning", tackling the root of the problem; namely the flagstates.

Another connected issue is the actual bridge complement; STCW-95, VIII-15 states:

The lookout is -day and night- standard modus operandi. By daytime, the lookout can be removed from the bridge; but only after careful assesment. This, in many cases, has been nibbled away to a mere OOW solo on the bridge, day or night, in all circumstances. The OOW, now also the sole lookout, has been burdened with extra tasks; GMDSS, ever-growing administration, ISM., etc...

A poor level of manning induces fatigue, and is a root cause for maritime accidents.





B.N.W.A.S., or "Bridge Navigational Watch Alarm System" is a system that will be phased in onboard ships in the coming year(s).

The system was proposed to IMO by Denmark. Denmark already had national legislation on watch alarms, since the M/V Karen Danielsen crashed into the Great Belt bridge in 2005. This too was caused by -amongst others- fatigue.


M/V Karen Danielsen after her crash with Great Belt bridge, Denmark.


IMO agreed on the idea, set up a time schedule for phasing in BNWAS, and wrote performance standards for the system.



BNWAS is -basically- a watch alarm system that requests bridge watchkeeping crew to periodically push a button; if not an alarm is triggered in the cabins of deck officers, and the captain.

BNWAS is aimed to detect inability of the watchkeeping crew on the bridge of a vessel.


Example of a Navitron BNWAS bridge panel; the captain switches on the system with a key. The system requests (with a prte-alarm)  the OOW to  reset button every cycle (here: preset to 10 minutes). If there follows no operator feedback, alarms will sound in cabins of other crew, captain, and finally, throughout the whole accomodation. Some systems use motion sensors on the bridge to reset the timer.


BNWAS is a piece of kit that may facilitate single-handed watchkeeping, and it may be perceived by many ashore as a quick-and-easy fix of fatigue problems.

"Watchkeepers falling asleep ? Put a buzzer beside them to keep them awake."

A modern bridge is already overflowing with alarms and buzzers; all frittering away the watchkeeper's attention, distracting from his main task. A system equipped with motion sensors is much less intruding. (But at least one classification society -LR- does not accept infrared motion sensors.)

BNWAS is not a magic potion: it will do nothing for the tired watchkeeper; to help him avoid "a succession of quite simple and small errors", the chain of errors than can lead to a catastrophe. It does not guarantee that a watchkeeper is mentally fit. Ships fitted with watch alarms have already crashed into islands, coral reefs, the works.

BNWAS is not adressing the real problems in the shipping industry, like undermanning,  proper hours of rest, OOW as sole lookout, etc... 

Watchkeepers can become unable for a number of reasons; not only sleep. A watch alarm is an extra safety net, to warn others onboard about a disabled watchkeeper.

And that is, in some situations, enough to save the day, without prejudice.


 Containership "Alvastar" smashes into a Greek island, november 2006. Probably the most embarassing grounding ever. Fatigue was also involved.




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