• Hydrex performs a wide range of propeller operations, keeping ships out of drydock

    Hydrex performs a wide range of propeller operations, keeping ships out of drydock


    Hydrex teams carried out a wide range of underwater propeller operations on tankers around the world. Among them a propeller blade straightening on a 248-meter ship in Algeciras, Spain, a blade cropping on a 183-meter vessel in Flushing, the Netherlands, and a spinner cone replacement on a 110-meter vessel in Rotterdam, The Netherlands.

    Underwater propeller blade straightening in Algeciras

    With three of the four blades of its propeller severely bent, a 248-meter tanker 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 a cold straightening of the blades.

    After the equipment arrived at the vessel’s location with one of the Hydrex workboats the team started the repair with a detailed underwater survey of the damaged propeller blades. The inspection revealed that the three blades had suffered deformations along the trailing edges.

    The team then carefully positioned the straightening machine over the bends of the trailing edges of the first blade and, in close communication with the team leader on the work boat, applied pressure to return the bent blade to its original state. This procedure was then successfully repeated for the other damaged blades, restoring the propeller’s efficiency.

    Underwater cropping of damaged propeller blades in Flushing

    Hydrex mobilized a diver/technician team to carry out a detailed inspection and necessary repair to the damaged propeller blades of a 183-meter tanker during the ship’s stop in Flushing.

    To make a full assessment of the damage, the team first performed an underwater inspection. This revealed that all four blades had been damaged. The affected areas of the blades therefore needed to be cropped to restore the propeller’s balance. The team then used the information acquired during the inspection to calculate and determine the correct measurements needed to modify the trailing edges of the propeller blades. The area to be cropped was marked out on each of the four blades and verified. Next the divers cropped the blades one by one and ground their edges to give them the correct radius. When the cropping was complete, the Hydrex technicians polished the blades to make sure that any remaining loss of efficiency would be minimal.

    All types of permanent underwater propeller repairs now possible
    Damaged propeller blades will have a below average performance.  The engine will thus have a higher workload, resulting 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 and optimum efficiency of the propellers can be restored.

    If straightening is not an option, the affected area on the blade will be cropped to restore the hydrodynamic balance. This is done to achieve the greatest possible efficiency for the vessel. This kind of repair is carried out with the propeller blade cutting equipment that was also developed by the Hydrex research department.

    Both types of repairs can be carried out on-site and underwater, allowing the ship to return to commercial operations without the need to drydock.

    The Hydrex R&D department has also developed a repair system that allows Hydrex to perform permanent underwater repairs to every type of propeller in dry conditions. All kinds of repair or maintenance work can be carried out on propellers, twin propellers, variable pitch propellers, azipod and collapsible thrusters.

    This is especially important news for offshore supply and work vessels, navy ships or any vessel under contract or on a location far away from available drydock possibilities. Staying on hire for underwater repairs will save precious time and money.

    This new repair system can be transported by air transport to any location around the world from the Hydrex fast response centers within a very short time frame. It can be assembled very quickly (12 hours) on-site.