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Annual r eport 2002 Annual r eport 2002 - Boskalis

Annual r eport 2002 Annual r eport 2002 - Boskalis

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Robert de Vlaming, Regional Manager<br />

<strong>Boskalis</strong> Offshore<br />

Precision dredging with high-tech equipment<br />

The fallpipe vessel Seahorse is equipped with a<br />

grab that can work at depths up to 1,000 meters<br />

below the surface. The state-of-the-art steering<br />

system means that the grab can be kept in position<br />

within tolerances of only a few centimeters.<br />

More and more often, oil and gas are being drilled for<br />

in deep waters. The Grand Banks near Newfoundland,<br />

Canada are a case in point. In order to protect the<br />

underwater oil and gas drilling installations against<br />

passing icebergs, <strong>Boskalis</strong> Offshore dredges ‘glory<br />

holes’ here. These are nine-meter-deep pits the size<br />

of a football field. They are located in the seabed at<br />

a depth of 120 meters. The new grab was specially<br />

developed for this purpose.<br />

“Development and production took more than a year,”<br />

explains Robert de Vlaming, Regional Manager for<br />

<strong>Boskalis</strong> Offshore. “A great deal of very high-grade<br />

technology was used. For example, the positioning<br />

system contains technology that is used in the<br />

aerospace technology. Nevertheless, the grab can<br />

be controlled by a single operator on the bridge.”<br />

The grab, with the remote system, weighs 80 tons<br />

and it is lifted on board by a hydraulic hoisting<br />

frame (an A frame). Furthermore, a second hoisting<br />

point was installed on the Seahorse so that the grab<br />

can be moved over the full length of the ship using<br />

a winch. And then there is the ‘umbilical cord’. This<br />

line feeds the grab with electricity, and with data in<br />

three dimensions about the position of the ship and<br />

its movements.<br />

The three links ensure that close steering of the grab<br />

remains possible, even at large depths. The active<br />

swell compensation also positions the grab with<br />

respect to the movements of the ship so that work<br />

is still possible in heavy seas.<br />

10 <strong>Annual</strong> R<strong>eport</strong> <strong>2002</strong>

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