Hydrex Conducts Underwater Stern Tube Seal Repairs in Panama and UAE

Hydrex Conducts Underwater Stern Tube Seal Repairs in Panama and UAE

In July, Hydrex diver/technician teams carried out underwater stern tube seal repairs on a 271-meter oil tanker in Fujairah, and on a 195-meter roro vessel in Panama.

Because both vessels were experiencing oil leaks, a fast repair was required by the classification societies. Using the company’s flexible mobdocks, Hydrex teams were able to perform both operations on-site and underwater, saving time and money for both owners.

Both stern tube seal repairs had to be carried out in less than perfect conditions. The water temperature in Fujairah was close to 45° Celsius while stormy weather caused strong swell. In Panama the circumstances were slightly less tropical, but still far from ideal. This brought about no problem for the Hydrex diver/technicians. They are trained to be flexible and adapt to constantly changing working conditions. On top of this, our technical department has many years of experience in dealing with all kinds of weather circumstances in locations around the world. The combination of this theoretical knowledge and the means for a practical execution, allowed Hydrex to perform both stern tube seal repairs in these harsh circumstances. This was done under the strictest possible safety regulations, to the highest quality standards and without any unnecessary delay.

Hydrex has carried out on-site, underwater repairs and replacements on all types of seals for a number of years now by creating a dry environment underwater, in which the divers can work. The technique has won prestigious Lloyd’s List Awards on two occasions. Several major classification societies have also awarded Hydrex certificates that accept the Hydrex revolutionary flexible mobdock technique to perform permanent underwater seal repairs which previously would have had to be done in drydock.

 Fujairah, U.A.E.

The lightweight flexible mobdocks packed in flight containers allowed for a very fast mobilization and a timely arrival in Fujairah of the Hydrex team. A storm was passing over when the team arrived at the oil tanker’s location. This meant that the Hydrex divers had to pause the repair on several occasions due to strong swell and could only start the underwater operations again when the weather had improved slightly and full safety could be guaranteed for the divers. This only caused minimal delay and did not prevent the job from being completed on schedule.

After the inspection, the team removed the rope guard of the vessel. Fishing lines tangled around the liner had caused the oil leak. These were removed by the diver/technicians. The team then installed the flexible mobdock around the stern tube seal assembly creating a dry underwater environment for the divers to work in drydock-like conditions, a necessity for permanent stern tube seal repairs. Next the split ring was disconnected and brought to the surface to be cleaned. Subsequently the team removed the three damaged aft seals one by one and replaced them with new ones.


When oil was leaking from the stern tube seal assembly of a roro vessel, Hydrex diver/technicians mobilized to the vessel’s location in Panama, together with all the needed equipment. After the diving team had set up a monitoring station, the operation started with a thorough underwater inspection of the stern tube seal assembly.

The underwater inspection revealed that a fishing line had caused the leak. The team removed the rope guard and installed the flexible mobdock around the assembly. After cleaning the entire assembly, the divers removed the first seal and replaced it with a new one which was then bonded. This procedure was repeated with the other two damaged seals. The team also installed a spacer ring, thus creating a new running area for the seals.

Both operations ended with the conducting of pressure tests with positive results, the removal of the flexible mobdock and the reinstallation of the rope guard.

Off hire causes a substantial loss of money. The teams therefore worked in shifts to perform the stern tube seal repairs within the shortest possible time frame. This saves both owners the time and money which going to drydock would entail.


Press Release, August 31, 2012; Image: hydrex