Underwater bow thruster propeller blade cropping on drill rig in Scotland11/05/2012
Last month a Hydrex diver/technician team cropped all four blades of the bow thruster of a semi-submersible drill rig stationed in Invergordon, Scotland for maintenance. The blades had suffered multiple dents and cracks and needed to be modified to restore the propeller’s balance.
The team first carried out a detailed underwater inspection of the propeller to get a full assessment of the damage. This revealed that each blade had suffered so many small damages that straightening the blades was not an option.
The information acquired during the inspection was then used to determine the correct measurements needed for the cropping. The area to be cropped was marked out on the four blades and verified. The team then 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.
The cropping was completed on-site, during a maintenance service. The operation restored the propeller’s balance and brought its performance as close to its optimum condition as could be achieved.Back