Five underwater stern tube seal repairs in one month

Five underwater stern tube seal repairs in one month

Recently our teams traveled across different continents and performed underwater seal replacements on five vessels in just over a month. Our diver/technicians travelled for repairs to Spain, then to Belgium, next on to Trinidad and Tobago, then to Colombia and finally back to Spain. By using our flexible mobdocks, all the repairs could be performed on-site and the ships did not have to go to drydock.

We can perform shaft seal operations on all types and sizes of shaft seals. This is illustrated by the range of ships our divers worked on: a yacht, a ferry, a roro vessel, a general cargo ship and a tanker.

On four of the five vessels oil leaks were the reason for the operation. These were caused by ropes and nets that got tangled in the stern tube seal assembly. The same procedure was followed for each repair.

Our flexible mobdock technique

After arriving on-site, the diving team first set up a monitoring station next to the vessel. Each operation started with a thorough underwater inspection of the stern tube seal assembly, and removal of the rope guard.

Our divers then cleaned the assembly and removed any fishing lines or nets that had become entangled. They then installed the flexible mobdock creating a dry underwater environment where they could work in drydock-like conditions.

Next the split ring was removed and brought to the surface to be cleaned. The divers then removed the first seal and replaced it with a new one which was bonded. Next, they did the same for the other two seals.

Hydrex truck and equipment next to yacht in Barcelona.

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

The operation on the yacht was slightly different. No oil leak was found on either of the two seal assemblies of the vessel, so only the two water seals needed to be replaced on each of the shafts. The procedure used for these repairs was the same as described above.


Taking advantage of our flexible mobdock technique, our men were able to carry out the repairs on-site and underwater. Because all the required material is ready to be transported at all times, no time was lost making preparations.

With Hydrex organizing everything from start to finish, the owners did not have to worry about making any arrangements for the repair. After the seals had been successfully replaced, they could sail the ships to their next stop free of oil leaks.

If ever you need assistance with the underwater part of your vessel, give us a call. We can then tell you if the repair is feasible and start working on its handling.

+32 3 213 53 00

Click on the images below for more case studies.

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