By carrying out both parts of the operation underwater the ship could stay operational and did not have to go to drydock.

After the team set up a monitoring station next to the vessel, the divers started the operation with a detailed inspection of the bow thruster and tunnel. 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 it was taken out.

The divers first action was to take off the external thruster tunnel grids to provide access for removal of the unit. Next pad eyes were welded inside the tunnel to hoist the thruster unit up and down.

The next step was to secure the gearbox with hoisting equipment. The team then disconnected the unit from the engine room and removed it from the thruster tunnel. It was then brought to the surface where it was overhauled by the OEM’s technician, with assistance of the Hydrex diver/technicians.

Because the thruster was fully assembled and prepared, it could be installed in its entirety without the need to create a dry environment in the tunnel as is required when the blades are installed separately. The team lowered it into the water and brought it into the thruster tunnel. They secured the unit and connected it to the engine room.

The operation ended with the removal of the pad eyes and the reinstallation of the thruster tunnel grids.

Conclusion
Hydrex assists shipowners with almost any problem they encounter with their vessel’s thrusters. A wide range of underwater repair or maintenance work can be carried out on all types of thrusters. An entire unit can be overhauled, propeller blades or seals can be replaced or repair work on a specific part of a thruster performed while the ship remains afloat. 

By performing the operation in Naples on-site and underwater the divers made it possible for the owner to keep the vessel out of drydock. The team worked in shifts around the clock to finish the operation as quickly as possible.