The Art of Dredging

Dredging and shipping

One man operated bridge


Following article IHC's magazine Ports&Dredging nr. 167 (follow the link) is written on the subject of one-man-operated dredgers, namely "Marieke", "Brabo", "Breydel" and others to follow. "Marieke" is a 5600 m3 hoppercapacity trailing suction hopper dredger (TSHD).

It's a new trend within the Belgian dredging company DEME: one-man-operated dredgers are given all kinds of kudos, including that they are said to be more safe and less prone to misunderstandings between operators. (Obviously: if you have only one operator left; misunderstandings between operators are a thing of the past.)

The article is written by IHC, and you can't blame them to praise the whole idea. IHC has always been client-oriented and business-minded, and they are not a stakeholder in the operation of one-man-operated dredgers. They have only been requested to design and build the darn things.

This was the manning situation before, on this size of dredgers: the wheelhouse was always staffed with two crewmembers, one of them (call him the first mate) handles the ship, navigation, lookout.

The other guy (the dredge operator) handles the dredging equipment, and, when the ship is sailing empty or loaded, checks the dredging equipment and performs preventive or corrective maintenance. During dredging he monitors the dredging equipment, and adjust settings. The actual operation of the equipment is already highly automated on most modern dredgers, and the operator mainly supervises an automated system during the actual dredging.

 The DEME videoclip on the entrance into service of "Marieke".  The clip fails to adress the real issues here.

Section A-VIII/part 3-1 par.16 from the 1995 STCW convention states that:

"In determining that the composition of the navigational watch is adequate to ensure that a proper look-out can continuously be maintained, the master shall take into account all relevant factors, including those described in this section of the Code, as well as the following factors:

Note that the master takes into account how many crew will stand watch. "Marieke" has been built with the aim that one man operates the whole ship, on which one can expect DEME to assert enough pressure on captains to make this a fait accompli.

.1 visibility, state of weather and sea;

.2 traffic density, and other activities occurring in the area in which the vessel is navigating;

Dredgers mostly work in area's with lots of shipping traffic, harbour entrances, rivers, canals, etc... (see this article) The situational awareness of the chief mate on a dredger must be high, demanding a large part -if not all- of his attention.

.3 the attention necessary when navigating in or near traffic separation schemes or other routeing measures;

Add to that: mostly  in a tightly controlled navigational area, requiring listening watch on two or more VHF-channels.

.4 the additional workload caused by the nature of the ship's functions, immediate operating requirements and anticipated manoeuvres;

Clearly this must be the dredging part; which is a fulltime job in it's own right.

.5 the fitness for duty of any crew members on call who are assigned as members of the watch;


Dredgers are operated by two teams, often standing a 12h on / 12h off watch shedule, sometimes an 8h/8h shedule.


Sure thing the layout of the wheelhouse is ergonomically adapted to one-man-operation.  Or more simply put: all is within reach of one man. As you see; the operator is overloaded with information through 6 displays and the normal plethora of alarms, etc...  (picture: operatordesk  TSHD "Brabo").

Since the wheelhouse is positioned in front of the vessel, and the dredging equipment aft, the lone operator needs CCTV-systems to check the equipment aft.

All this seems ok, at first.

But consider this: monitoring all this data, and operating the whole ship with one man, requires more dependance on sensors and high automatisation. Every technological layer that is placed between the operator and the ship is prone to faulty behaviour. One of the core reasons for the very existence of an operator is that he's there when faults come up in the operating system, and that he can step in before any damage occurs.

But if one man has to operate the whole ship, evidently reliance on the operating system must be higher, with all risks involved along that road.

I have -plenty of times- seen how an operator suffers data-overload, and makes grave mistakes because of that, with the data presented in front of him, but unable to act because a human being can only handle so much info at the same time, and has a limited attention-span.

The old adagio was "One man's navigation is always wrong."

The whole idea of one-man-operated-dredgers also ignores the fact that two operators will check and correct each other. A good team of two man will have no misunderstandings, and the sum of them will be more than two.

The design of the wheelhouse onboard the new DEME-dredgers takes watchstanding to a whole new level: not only navigation, lookout, but the entire dredging job is to be handled by one person. This is way beyond the STCW-convention.

This concept is poised to fragment an operator's attention, to cut corners of longstanding good navigational practices,

It's a recipe for disaster.

Marc Van de Velde


"A recipe for disaster" , see also following article on an incident with the "Breydel" .



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