What caused this vibration?
In 2016 the Lady A was involved in a grounding incident whilst under tow. This incident damaged the port propeller blades which were repaired during later dry dock. However, when back in service the yacht still suffered minor vibrations and it was agreed with classification society ABS to investigate this matter at next scheduled dry docking, and here MarineShaft was contacted.

Class approved cold straightening
We received the Ø235 x 11270 mm long propeller shaft in our workshop in Hirtshals and performed alignment test and measurement.

The bend of the propeller shaft was 1.7 mm. Even a minimal bend can cause damaging vibrations to a vessel.

Laser Cladding
Before we proceeded with the cold straightening, the shaft was inspected for cracks with a 100% liquid penetrant test carried out by us and Force Technology. The shaft was found intact and cold straightening was carried out. Besides a bend the propeller shaft had suffered damage on the forward bearing journal due to corrosion.  This we repaired using our laser cladding technique welding up the cavitated areas with Inconel 625 – a stainless steel material ideal for reconstruction. Check out our video about laser cladding

Our laser cladding welding technique ensures a 100% binding to the base material and we can machine afterwards requiring no previous post-heat treatment, as the laser cladding leaves minor heat input.
This was followed by the final inspection and run-out test carried out by ABS surveyor before the shaft was returned to Gibraltar.

M/V Lady A was able to get this 11270 mm long propeller shaft straightened and repaired within 2 weeks.