(With extra pictures) Hydrex has removed and installed a new thruster underwater during a vessel’s stop in Limbee, Cameroon.
During an inspection of a 69 m offshore supply vessel it became clear the thruster was damaged too severely for an on-site repair and needed to be replaced with a new one. To save time and money, it was decided to replace the thruster underwater instead of in drydock and on location in Cameroon.
The removal of the old stern thruster unit and the installation of the new unit took place during a single operation. A team was mobilised to Cameroon and set up a monitoring station next to the berthed ship.
Detaching Blades
One by one the diver/technicians then 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 stern thruster engine room for the removal of the unit so that there would be no ingress of water once the unit was taken out.
Extracting the Thruster
The team then disconnected the stern thruster from the thruster room and carefully lowered it in the tunnel. The divers extracted it from the tunnel and brought it to the surface. Simultaneously, a blind flange was installed to seal off the thruster tunnel from the engine room.
Installing the New Thruster
For ease of handling, the new stern thruster unit was put on a cradle. The divers then lowered it into the water and brought it inside the tunnel.
Next, the diver/technicians sealed off the thruster tunnel with Hydrex flexible mobdocks and emptied all water from it. This created a dry working environment in which they could complete the reinstallation of the stern thruster unit in the best possible conditions. They repositioned the gearbox using chain blocks and secured it with bolts.
The thruster propeller blades were then reinstalled one by one and the thruster unit was reconnected to the engine room.
Picture: Hydrex diver getting ready for underwater operation
Below a photoalbum of the operation. Please click the pop-out link (the little squares at the bottom right) to view the pictures in their proper dimensions.
