â€œGoing to drydock was not an option as the nearest suitable location was South Africa and this would have taken the repairs far beyond the available time frame. On hand, at the Hydrex Office in Port Gentil, Gabon, was a large mobdock (mobile mini drydock) measuring 9 x 6 x 2 meters and weighing over 25 tons by itself that was constructed under Hydrex proprietary technical supervision in Belgium. This allowed for very fast mobilization and execution of the 40 ton azimuth thruster repairs that was just carried out,â€ said Alex Meerbergen, head of the Hydrex in Port Gentil, Gabon.
First an operations base was set up on a work barge next to the crane barge. The mobdock was then installed and all water was pumped out of it to create a dry working environment underwater. The water sensitive parts of the thruster were then sealed off after which the mobdock was removed. The thruster unit was lowered onto a special support unit under the barge and brought to the work barge.
Subsequently Hydrex engineers dismantled the thruster under the supervision of a representative of the manufacturer. The entire gearing was taken out, thoroughly checked, cleaned and reinstalled. The thrusterâ€™s propeller was disconnected in its entirety and replaced by the propeller of a spare thruster that had also been brought onto the barge. The spare thruster (together with the old propeller) was then brought to shore for transportation to the workshop where it would be overhauled. Once it is returned the owners will have a fully operational thruster ready to be installed if another breakdown should occur in the future.
Meanwhile the fully checked original thruster with its new propeller was reinstalled into the crane barge following the reverse procedure. Finally commissioning and testing was carried out satisfactorily. The offshore unit is fully operational again, well before the start of its next operation. This presented a major saving in time and money for the owner as the offshore unit did not have to go off hire to be taken to drydock.
Meerbergen went on to say, â€œIt was an extremely precise operation requiring a great deal of coordination and organization to ensure that all went smoothly. There were detailed safety and technical procedures that had to be met in order to access the thruster from within the engine room as the thruster was located outside the vessel under the water line. Despite this, all technical work was performed smoothly by qualified Hydrex diver-technicians. They worked in shifts to finish the operation as soon as possible and without any loss of quality.â€
Underwater ship repair (http://www.hydrex.be) and maintenance company, Hydrex N.V. was founded in Antwerp, Belgium in 1974. The company, serving both the shipping and offshore industry, has grown to become one of the leading international companies providing a comprehensive range of underwater maintenance and repair services. Hydrex specializes in cutting edge underwater repair and maintenance technology and solutions that are performed in-situ resulting in ship owners often finding drydocking is not necessary so time, trouble and expense are saved. Hydrex underwater services cover all types of repair including highly technical repairs or replacements such as thrusters, propellers, rudders, stern tube seals, and damaged or corroded hulls. All job categories are approved by classification societies. For more information on Hydrex and to contact the West Africa office or one of their other international offices visit http://www.hydrex.be.