Offshore Installations: No Pitch Control, No Problem

Emergencies happen in even the remotest locations. While operating off the West Coast of Africa, pitch control was lost on a retractable azimuthing thruster. After the original equipment manufacturer (OEM) performed a full evaluation, it was determined that there was an internal defect within the lower unit of the azimuthing thruster. This required immediate attention considering the critical mission of the vessel and its location.

As the vessel’s owner had worked with the Subsea Solutions Alliance on other vessels with thruster incidents, he was fully aware of the capabilities of the diver / technicians of the Subsea Solutions Alliance. As the member companies of the Subsea Solutions Alliance are the preferred supplier of underwater services to the OEM, the vessel’s owner engaged both the OEM and the Subsea Solutions Alliance to develop a suitable repair to this damaged thruster.

Meetings commenced at the OEM’s facilities in Europe to determine an approved method of repair to this retractable azimuthing thruster as a repair of this type was never performed before. A repair procedure was developed, timeline created and critical spare parts were packaged and shipped to the repair location in West Africa.

Concurrently, the Subsea Solutions Alliance office in The Netherlands packaged the necessary dive support gear and critical tools for the execution of this repair. Upon arrival of the gear and critical spare parts, trained diver / technicians from the Subsea Solutions Alliance’s office in The Netherlands and OEM service support was mobilized to the site.

Within a day of mobilization a dry environment was created inside the retraction column of the azimuthing thruster so that a repair to the unit could be executed. The propeller blades were removed from the propeller hub and the lower gearbox was methodically disassembled in accordance with the OEM repair procedure and under the supervision of the OEM.

The propeller hub was completely disassembled and it was found that a ‘sliding block’ had failed and was jamming into the ‘crank ring’. After consultation with the attending OEM service engineer, the diver / technicians removed the damaged sliding block and crank ring from the propeller hub.

Upon inspection it was determined that these critical components were the root cause of the pitch control problem and were replaced. Reassembly of the azimuthing thruster immediately commenced, tests were performed and the team in accordance with the time line completed the repair.

With the vessel back to work, the client credited the repair to the dedication and professionalism of the diver / technicians from the Subsea Solutions Alliance. Experience does make a difference and by maintaining a fully employed workforce, the member companies of the Subsea Solutions Alliance are able to continually train and develop its diver / technicians to become the standard to be measured against. We look forward to applying their skills to your installation!

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