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  • Severe bend of a propeller shaft 
  • Grena Knutsen - repair of 4 huge propeller blades
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When time is money - this bend propeller shaft belongs to a Cruise Ship

Most bends of shafts are not visible for the eye, but recently we had this 16460 mm long propeller shaft with a severe bend in the workshop for cold straightening.

We received the job from Wärtsilä Danmark and the propeller shaft belongs to a Cruise Ship. After agreement with the owner and Wärtsilä we will not mention the name of the cruise ship that suffered an unplanned grounding in November while cruising with passengers along. An underwater inspection revealed damage to the propulsion unit and the current cruise was cancelled and the vessel went by its own power to port where the passengers were disembarked and the Cruise Ship continued to another port for drydock repair.

An urgent repair was in need and we received the propeller shaft in our workshop a Thursday afternoon. The propeller shaft was sent by aircraft  to Denmark where our team was ready to work 24/7.
Before any cold straightening we run an ultrasonic test of the bended area and inspected by the classification society – in this case Bureau Veritas. The cold straightening was completed and bearing journal was machined to a new diameter.
Scratches and impact marks on the coupling end of the propeller shaft we repaired with micro welding leaving no heat input in the base material. This welding requires only hand grinding and polishing afterwards. (read more about micro welding here)

Finally, a magnetic particle test of the propeller shaft after cold straightening and an Ultrasonic test of cold straightened area in aft bearing journal was carried out and a Bureau Veritas surveyor made the Final inspection and run-out measurement of the propeller shaft. 

The following Thursday morning – less than 7 days later - the propeller shaft was repaired, packed for air freight and on its way back ensuring the cruise ship being able to re-enter service after a short downtime.
Shuttle Tanker M/V Grena Knutsen

Cavitation on propeller blades is an un unavoidable problem and also the situation for the 4 bronze propeller blades belonging to the Shuttle tanker M/V Grena Knutsen. During a planned docking at a Danish Shipyard MarineShaft received the 4 blades weighing 6 ton each for repair.
We welded the cavitated areas and manufactured 4 new plugs. DNV-GL class-approved the repair.
I was lucky to find many of our propeller blade welders in the workshop to get a good shut showing the impressive size of the 4 blades.

Best wishes to you for a Merry Christmas and a Happy New Year. Thank you for your interest in our newsletter and I look forward to sharing the repairs to come.
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MarineShaft · Pier 2 · Hirtshals 9850 · Denmark

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