Danish firm’s specialised and class-approved cold straightening technique restores bent shafts to their original condition without the need for heat
Denmark-based MarineShaft has recently carried out a major repair involving the cold straightening of two intermediate shafts on a 65m-long superyacht. The propeller shafts had suffered minor deflection and wear on the coupling ends and bearing journals, as well as pitting damages to the centre and forward parts of the shaft body.
The shafts were cold straightened, and liquid penetrant tests were conducted before and after the straightening work. The pitting and damaged areas on the coupling end and bearing journals were machined and, using laser cladding, these areas were rebuilt and machined to their original dimensions.
Another recent superyacht repair undertaken by MarineShaft involved work on a vessel that had suffered damage to both its rudder and propeller. While the luxury yacht was docked at a European shipyard for extensive upgrades, the equipment was sent to MarineShaft’s workshop in Hartshals, Denmark. Both propeller shafts had excessive wear, and it was decided that the best option was to replace them.
The job included: manufacturing the port and starboard stainless steel propeller shafts, as well as a new hydraulic coupling and nuts; modification of the blade shape on the fixed propellers after geometric measurement and balancing; and final fitting and class approval by Bureau Veritas (BV).
The same vessel also requested repairs to its two-rudder arrangement, and this project is still underway at MarineShaft’s workshop. This will include the repair of worn rudder stock journals, stock keyways and upper threads; post-weld heat treatment; a repair to the rudder tiller by laser cladding; and the manufacturing of tiller keys and nuts for the upper threads. All the work will again be class approved by BV.
