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Stern tube seal repair on OSV



Type of project:

  • Carry out bonding of the port and starboard outboard and inboard stern tube seals.
  • Replace seal box liners.

Customer name: UK Offshore supply vessel fleet operator

Location: Ulsteinvik, Norway

Initial enquiry: Our team were asked to attend the vessel whilst in dry dock in Norway to replace the shaft seals on the forward and aft seal boxes, utilising parts supplied by the customer.

Project description:

The project started with a meeting between our service team and the shipyard’s supervisor and superintendent. This initial phase was instrumental in establishing a clear scope of work, as well as presenting the Risk Assessment and Method Statement (RAMS).

Our team then meticulously organised the required tools and spare parts before commencing the work. During the disassembly of the port and starboard seal boxes, our engineers identified excessive wear on the liners. This discovery was communicated to the superintendent, and after a thorough discussion, it was decided to include the replacement of the seal liners within the project scope.

The subsequent steps involved the removal of the port rudder, disconnection of the inboard coupling, and control rod, followed by the extraction of the prop shaft with the collaborative efforts of the shipyard team. The same methodical process was then repeated for the starboard side.

Once the prop shafts had been successfully removed, our team transported the seal boxes to the workshop, where they were carefully disassembled, cleaned, and expertly reassembled. During this meticulous process, the engineers installed new seals, gaskets, bolts, and liners, all of which were provided by the customer. Additionally, our team addressed the corrosion in the sealbox chamber, ensuring a secure seal seating area.

The port and starboard seal boxes were reinstalled into the vessel, and the prop shafts were reinserted and securely attached to their stern tubes. Precise alignment of the liner runouts was achieved in accordance with Simplex’s tolerances and guidelines, with bolts secured using lock wire. The seal boxes were then filled with oil.

The project’s final stages involved the removal of the plug on the propeller, filling of the stern tubes with oil, installation, and filling of the inboard sealbox tanks. A comprehensive inspection was conducted to check for oil leaks, and no leaks were observed by the team.

Finally, the installation of the rudders was successfully completed by the shipyard, with our MIT service team actively providing guidance and overseeing the advancement of the cone, adhering to Kongsberg’s specifications.

Unfortunately, on this project, the team could not perform a sea trial due to ongoing issues with the engine coolers, which a third party was rectifying. However, the Superintendent gave this feedback about the team;


(I have) nothing but high praise for the attitude, communication and flexibility (of the team) and as always it was a pleasure to work with. They adapted and completed the job over and above scope and as professionally as any team.


Our engagement with the UK Offshore Supply Vessel Fleet Operator in Ulsteinvik, Norway exemplified our commitment to excellence, precision, and collaboration. This project not only ensured the reliability and safety of the vessel but also showcased our expertise and dedication to delivering exceptional maritime solutions.

We sincerely appreciate the trust placed in us by our valued customer and look forward to future opportunities to serve the maritime industry.




Find out more about our dry dock service and repair capabilities here:

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