• Fast on-site propeller repairs in Germany and Spain keep ships out of drydock

    Fast on-site propeller repairs in Germany and Spain keep ships out of drydock

    19/04/2013

    Last month, Hydrex teams carried out underwater propeller operations in Bremen and Rostock (Germany) and Algeciras (Spain). In Algeciras a 200-meter vehicle carrier had its five propeller blades cropped. In Germany three of the five blades of a 183-meter tanker were grinded, re-profiled and polished while a fourth one was straightened. Both repairs were carried out on-site, preventing the need to drydock.

    Damaged propeller blades will have a performance below average.  The engine will have a higher work load. This results in increased fuel consumption and added stress. By taking advantage of Hydrex’s in-house developed cold straightening technique, damaged blades can be straightened underwater. In this manner optimum efficiency of the propellers can be restored. If straightening is not an option, the affected area on the blade will be cropped. By doing this the greatest possible efficiency is achieved for the vessel. These repairs are carried out with the Hydrex propeller blade cutting equipment. Both types of repairs can be performed on-site and underwater. This allows the ship to return to commercial operations without the need to drydock.

    Underwater cropping of damaged propeller blades in Algeciras
    With all five blades of its propeller severely bent, a 200-meter vehicle carrier in Algeciras needed a fast, on-site solution to restore the propeller’s balance and efficiency. Hydrex diver/technicians are trained to carry out repairs underwater in the shortest possible time frame. A team was rapidly mobilized to the ship’s location close to the Hydrex office in Algeciras Spain to perform propeller blade cropping.

    An underwater inspection revealed that all five blades had suffered deformations along the trailing edges too extensive to be straightened.

    Cropping the affected areas of the blades was the only option. This would restore the propeller’s balance. The team then calculated the cutting line needed to modify the trailing edges of the propeller blades. The area to be cropped was marked out on the five blades and verified. Next the divers cropped the blades one by one and ground their edges. This gave them the correct radius. Finally, the Hydrex technicians polished the blades to minimize any remaining loss of efficiency.

    Underwater propeller blade straightening in Bremen and Rostock
    One of the five blades of a tanker’s propeller was severely bent. Three of the others four propeller blades were also damaged, but less severely. A fast, on-site solution was required to restore the propeller’s balance and efficiency. A Hydrex team therefore mobilized rapidly to the ship’s location in Bremen.

    The underwater survey of the damaged propeller blades revealed that three blades had suffered cracks and dents along their trailing edges. The Hydrex diver/technicians therefore ground away the cracks and polished the edges of these blades.

    The ship then continued on its schedule. In the next port of call, Rostock, the team met up with the vessel again. The team positioned the straightening machine over the bends of the trailing edges of the bent blade. The blade was then returned to its original state. This restored the propeller’s efficiency.

    These repairs were carried out in extreme winter circumstances. Icy conditions like this will not prevent Hydrex divers from providing the service you need. They are professionally trained to perform a wide variety of operations, both above and below water, anywhere in the world and under extreme conditions.

    Conclusion

    Our R&D department is constantly looking into ways to enhance the available propeller repair techniques even further to improve our services. New models of both the straightening and the cutting machines have recently been put into service. These allow us to straighten blades that could previously only be cropped and to crop extremely damaged blades with only a minimal loss of efficiency for the propeller.

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