Underwater Activities at Hydrex One of Hydrex’s diver/technician teams reently carried out an underwater stern tube seal repair on a 300 m containership berthed in Antwerp. The ship was suffering from an oil leak, making an immediate repair necessary. Using a Hydrex flexible mobdock the team was able to carry out the entire operation on-site and underwater, saving the owner an expensive and timeconsuming trip to drydock. Once the operation was confirmed all preparations were handled swiftly and the lightweight equipment was mobilised immediately from Hyrex’s headquarters in Antwerp. After arriving on-site, the diving team first set up a monitoring station next to the vessel. The operation then started with the removal of the rope guard and a thorough underwater inspection of the stern tube seal assembly. After the inspection the divers cleaned the assembly and installed the flexible mobdock. By doing this they created a dry underwater environment so that they could work in drydocklike conditions. The split ring was then removed and brought to the surface to be cleaned. After cleaning the entire assembly, the divers removed the first seal and replaced it with a new one which was bonded. The procedure was repeated with the other seals. A successful operation was concluded with leakage tests, the removal of the flexible mobdock and the reinstallation of the rope guard. Working together with the OEM allowed Hydrex to provide the customer with original spare parts which guarantees the best quality material. A technician of the seal manufacturer was also present during the operation. By organising everything from start to finish the owner did not have to worry about making any arrangements for the repair. After the seals had been successfully replaced he could sail his vessel to her next stop free of oil leaks. Meanwhile, oil was leaking from a propeller blade of a general cargo vessel, which could not use her propeller anymore and the blade seal needed to be replaced. Time was critical and a fast and on-site solution was essential in keeping the ship on schedule. Hydrex therefore mobilised a team to the ship’s location in São Vincente, Cape Verde to perform emergency repairs. The team started the repair with the installation of chain blocks to rig the blade. They then removed the blade bolts and lifted the
A Hydrex diver/technician removing propeller blade bolts
blade. The damaged blade seal was replaced with a new one. After the new seal was installed the blade was repositioned and the bolts were secured again. A successful oil pressure test and an underwater inspection of the entire propeller were performed, concluding the repair. With the oil leak repaired the vessel was able to leave Cape Verde with a working propeller. The owner could keep to the sailing schedule without any delay. Removing a propeller blade allows Hydrex to perform work on the propeller while the vessel stays afloat, but sometimes one or more blades need to be replaced or overhauled. Divers can remove them and replace them or reinstall them when they return from the workshop. A good example was the operation on a ro/ ro ship berthed in Tasmania. This operation
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consisted of the underwater replacement of the damaged blade as well as the opposite blade of the main propeller of the vessel. This propeller was designed with a special system to close it off from water ingress during a blade replacement. The operation was performed under supervision of an engineer of the propeller’s OEM. Once the first blade had been lifted, a spare blade was lowered into the water and put in position. After it was secured and the bolts put on torque, the ship crew turned the propeller 180° to bring the opposite blade in 12 o’clock position. The Hydrex diver/technicians then repeated the same procedure on this blade. The operation was finished swiftly to enable the owner to sail his ship on schedule. No costly drydock visit had to be planned.
