H y d r e x Team Performs U n d e r w a t e r W o r k O n S a i p em

This past summer marked the entrance of large crane vessel Saipem 7000 into Botlek Harbor of Rotterdam. Within hours of its arrival, Hydrex's diving and repair crew boarded the vessel to carry out underwater servicing work, which required extensive dismantling of the vessel's thrusters.

The Hydrex team, which did research prior to the Saipem job, removed some the vessel's large thrusters. Since the available water depth was not sufficient to allow for the lowering and safe passage of them, dredging work was the first underwater task to be completed Hydrex's underwater ship repairers dug a trench using a six in. salvage pump.

Five days after intense dredging and removal of debris and rocks — a crater of 5 m deep was created under one of the four main propulsion thrusters.

Concurrently, Saipem's engineers had disconnected the 70 ton thruster onboard, which was then lowered underwater, and with the help of Hydrex divers, hoisted to the surface so that maintenance work could be performed.

The vessel was then transported to a different location beneath the crane mammoth to commence dredging under one of the six DP retractable thrusters.

Access space had to be created for the installation of a large cofferdam over the thruster-garage.

Exact positioning and installation is required to install these cofferdams. The team also removed the vessel's heavy lower gearbox of thruster number five.

The removal was carried out by the smallest crane vessel in the port of Rotterdam due to the difficulty in having to pass under Saipem's bracings.

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Maritime Reporter Magazine, page 38, Mar 2001

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