Recently Hydrex teams carried out a wide range of underwater propeller operations on tankers around the world. Among them a spinner cone (Propeller Boss Cap Fin –PBCF) replacement on a 110-meter vessel in Singapore, a propeller blade straightening on a 248-meter ship in Algeciras, Spain, and a blade cropping on a 183-meter vessel in Flushing, the Netherlands.
Underwater spinner cone (PBCF) replacement in Singapore
Hydrex was contacted to install two new spinner cones (PBCF) during a LPG tanker’s scheduled stop in Singapore.
The diver/technicians removed the port side propeller spinner cone (PBCF) and hoisted it on board the vessel. After they had cleaned the area under the spinner cone (PBCF), the team lowered the new cone into the water and positioned it on the propeller. When this was done, grease was inserted in the space underneath the propeller cone for lubrication and the bolts were put on torque and secured with wire, finishing the replacement of the first spinner cone (PBCF).
The divers then repeated this procedure with the starboard side propeller.
Underwater propeller blade straightening in Spain
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. 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 underwater operation 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 the Netherlands
In September, 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 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.
Press Release, October 31, 2012