When a military operations vessel experienced a failure in the feedback system of one of its thrusters, Hydrex mobilized a team to Den Helder, the Netherlands, to perform the necessary repairs afloat with the use of the company's flexible mobdocks.
These lightweight flexible mobdocks are easy to transport and are used to close off the thruster tunnel on both sides, allowing divers to empty all water from the room and create a dry environment around the unit. In this way the required operation can be performed underwater in dry conditions, whether it entails the removal or installation of an entire unit or, as was the case with the operation described in this article, repair work on a specific part.
The repair started with the installation of the flexible mobdocks and emptying of all water from the thruster tunnel. The bolts securing the cover of the gearbox were removed and two of them were replaced by threaded bars. This enabled the Hydrex diving team to push back the hood while keeping it in the correct position. A video inspection of the internal part of the gearbox could then be performed, revealing that the feedback rod had broken off.
A replacement rod was acquired and brought inside the tunnel where it was installed. The cover was then slid back into place and secured again. Tests confirmed the repair to be successful and the flexible mobdocks were removed.
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