In July, Hydrex performed the removal of a bow thruster that needed to be overhauled, and reinstalled a spare unit in one take. Both parts of the operation were carried out during a 200-meter container vessel’s stop in Antwerp.
A diver/technician team carried out a preliminary inspection and took the necessary measurements prior to the ship’s journey to Antwerp, while the ship was berthed in Algeciras. This allowed the Hydrex technical department to prepare every step of the operation in detail to make sure that the team could carry out both the removal of the old bow thruster unit and the installation of the new unit during a single operation, in the fastest possible time and without any loss of quality.
Together with all the necessary equipment, the team mobilized from the headquarters in Antwerp to the vessel’s location. One by one the diver/technicians detached the blades and replaced them with blind flanges to prevent oil from leaking from the thruster. In the meantime, initial preparations were made in the bow thruster engine room for the removal of the unit so that there would be no ingress of water once the unit was taken out.
Next the team cut the support brackets connecting the gearbox to the thruster tunnel and secured the unit with chains. It could then be fully disconnected from the thruster room and was carefully lowered, extracted from the tunnel and brought to the surface. Simultaneously the team installed a blind flange to seal off the thruster tunnel from the engine room. Once the old unit has been overhauled it will be used as spare thruster for future operations.
Next the new bow thruster unit was put on a cradle which was designed specially for bow thruster operations and which prevents the unit from tipping. As it can be adjusted to the size of the thruster, it allowed the Hydrex divers to bring the unit back into the thruster tunnel in one take.
The diver/technicians then sealed off the thruster tunnel with the Hydrex flexible mobdocks and emptied all water from it. This created a dry working environment for them in which they could complete the reinstallation of the bow thruster unit in drydock-like conditions. Next they repositioned the gearbox using chain blocks and secured it with bolts. The thruster propeller blades were then reinstalled one by one. The team completed the operation by reconnecting the thruster unit to the engine room.
Hydrex took on, organized and executed the entire job, start to finish, relieving the customer of all the hassle of coordination, planning and supervision. This was done in close cooperation with the customer and third party suppliers.
To keep the delay for the customer to the absolute minimum, diver/technicians worked in shifts around the clock. By performing both the removal and reinstallation of the bow thruster unit underwater the vessel did not have to go into drydock, saving the owner valuable time and money.
Press Release, August 31, 2012; Image: Hydrex