Last month, one of our diver/technician teams carried out an underwater stern tube seal replacement on a 180-meter container ship berthed in Algeciras. Seawater had been found in the air chamber and the seal leak alarm had gone off, confirming that the seals where damaged and needed to be replaced.

Using one of our flexible mobdocks, the team was able to carry out the entire operation on-site and underwater, saving the owner an expensive and time-consuming trip to drydock.

Once the operation was approved, all preparations were handled swiftly, and the required equipment was mobilized to the vessel. Because the ship’s mooring location could only be reached via the water, our team made use of a workboat during the operation.

The operation started with the removal of the rope guard. Our diver/technicians then took a tail shaft wear-down measurement and cleaned the seal housing components.

The flexible mobdock was installed around the stern tube seal assembly. Communication systems, a camera and lighting were installed inside the habitat, creating a dry underwater environment where our technicians could work in drydock-like conditions.

The intermediate rings were then opened and the liner and rings thoroughly cleaned. A fishing net tangled around the damaged seals was removed by our divers. New seals were then installed and bonded, after which the intermediate rings were closed again.

A successful operation was concluded with leakage tests, the removal of the flexible mobdock and the reinstallation of the rope guard.

Working in drydock-like conditions on-site

Taking advantage of the Hydrex flexible mobdock technique, the entire seal replacement could be carried out with the vessel afloat. The system creates a dry working environment around the stern tube seal assembly, allowing our diver/technicians to perform the work under conditions similar to those in drydock.

Having the equipment and experienced personnel available for rapid mobilization also means that repairs can be organized without losing valuable time. This is especially important when a damaged stern tube seal requires immediate attention.

Despite changing currents at the location, the team was able to carry out the complete procedure as planned in just under 48 hours.

The fact that Hydrex organized everything from start to finish meant that the owner did not have to make separate arrangements for the underwater part of the repair. Our team arrived at the ship with the equipment needed to carry out the seal replacement and complete the operation on-site.