A team of experienced Hydrex diver/technicians performed underwater thruster operations on two vessels simultaneously in Coatzacoalcos, Mexico. Repairs were carried out on both azimuth thrusters of an FPSO while the thruster seals of a heavy load carrier were replaced.

Both vessels are managed by the same company. They were suffering from leakage problems on their propulsion system. We received these inquiries and were able to combine both repairs in one operation. This gave our costumer the advantage of only one mobilization for both vessels and kept the cost within budget.

The stern thruster tunnel of the heavy load carrier was sealed off with our flexible mobdocks. All water was then emptied from the tunnel, creating a dry workspace around the thruster unit. A full inspection of the unit revealed that all blade and shaft seals were leaking. Our diver/technicians first replaced the four blade seals. The three shaft seals were then replaced in cooperation with the representative of the OEM.

The other vessel was an FPSO which had suffered a problem in the oil distribution box of one azimuth thruster. A special cofferdam was designed by the Hydrex R&D department to create a dry environment around this part of the thruster. This enabled our team to perform a complete repair without removing the thruster. The other azimuth thruster had more serious problems and a complete removal was required. As the thruster was not designed to be removed underwater, we created a custom procedure for this.

Flexibility is an important element of every job we carry out, but in this case it was crucial that both repairs were adjusted to each other. Because we were able to fulfill the needs of our customer he could keep the vessels out of drydock and on contract.

Conclusion
Performing jobs like these on a tight schedule takes a lot of planning. This can only be done successfully by staff who have familiarity with such operations and the relevant know-how and equipment. Hydrex has a technical department capable of executing all the required planning. Our diver/technicians are trained and qualified to perform the full range of required class-approved repair procedures in even the harshest conditions. Hydrex also has very well-equipped rapid response centers including customized workboats, ready to mobilize directly to the job site. An effective, competent team is the only way to consistently achieve a high quality result in the short periods of time usually available to ships.