Posted: 26th July 2016
Being able to repair a vessel without any interruption to its schedule will be music to the ears of ship owners, charterers, crew and the fleet superintendent too. And in our latest case, UMC were able to offer their expert advice to evaluate and advise on suitable in-water propeller repair solutions.
John-Paul Engels, general manager, explains: “The client requested the repair did not involve cropping the deformations of this 6300mm diameter, four-bladed propeller. We reviewed the damage and were confident that any deformations could be successfully straightened in-water using our network partner – One Ocean’s™ cold static straightening equipment and technology.”
Three propeller technicians were mobilised to execute the repair supported by a local dive team who supplied diving equipment and logistics support.
“The team started with a detailed inspection to confirm repairs of the deformations could be conducted without the need for dry docking,” says John-Paul. “With no micro fractures visible, cold static straightening of the blades resulted in successful restoration of the edges back to near design geometry. Residual deflections and small mechanical impacts were removed using grinding techniques and faired back into the original blade edge contour, leaving a minimum of 120 degrees angle at the apex,” he adds.
To determine if the blades would require balancing following the smoothing of the mechanical impacts a mass balance calculation was conducted explains Jean-Paul: “The material removed was well within the tolerance of the propeller so there was no further work required.”
The repair was documented with still photographs and video footage, which confirmed the blade surfaces were free of any micro fractures and the propeller was released accordingly.
Within less than eight hours the propeller was fully restored while cargo operations were ongoing to allow the vessel to maintain its schedule.