Recently Dive Marine Services attended to a vessel calling Singapore that required urgent attention. They experienced noise and vibrations from the propulsion system. When a ship’s propeller is damaged it becomes imbalanced which reduces the vessel’s performance and efficiency and leaves it prone to severe vibrations that can lead to bearing failure of the main shaft. This ultimately hinders the vessel from continuing operations with off-hire and other costs or delays as possible results.
Based on the severity of the propeller and the complex assignment, our specialized repair team from Dive Marine (Europe) BV was deployed to Singapore.
A preliminary inspection by our specialists revealed that the propeller was impaired as all four blades were damaged. Two blades had broken tips while the other two suffered from cracks in the leading edge. The damage was further exacerbated as the broken blades were adjacent to each other that made a simple cut-to-balance operation unfeasible. The damage was so critical that the vessel couldn’t continue its voyage any further.
The teams of Dive Marine Services Singapore and Europe then measured all damages and plotted it onto the propeller’s mock-ups to give a visual overview of the damage to all stakeholders and devise a strategy for repair. Our inhouse capabilities and experience with complex repair situations allows our divers to provide multiple plausible solutions. The team worked closely with the owner and class to obtain approvals and finalize the repair proposal on the same day. The repair agreed upon involved replacing one of the broken blades with a spare blade onboard, and performing cuts to calculated dimension on the remaining blades to ensure the propeller is balanced.
As it was a 4-blade propeller, the blades were worked on in pairs i.e., blades attached opposite to each other. So, each set of blades had a blade with a broken tip and a crack. For the first set of the blades, one was replaced whereas the crack on the other was cut out. This exact cut was also made on the new blade. For the second set of the blades, a straight cut was performed on the broken blade which was also replicated on the opposite blade. Although this blade only suffered a small crack, it’s tip had to be cut out the exact way to ensure the blades were balanced.
Dive Marine’s uniquely designed propeller cutting machine allows to perform such precision work easily and efficiently. Once all the repair works were performed, the vessel was trimmed (adjusted) to allow the blade to come out of the water for replacement.
The old blade was replaced with the new one and lowered in position. All bolts were tightened to the maker’s recommended torque and secured by welding. Pitch testing confirmed all blades were installed correctly with no leakages. To conclude the repair, an independent NDT party performed NDT tests on all blades in accordance with Class approved repair procedure. No further cracks were detected in the findings. The propeller was given a 2-stage polishing to Rupert Scale A finish prior to handing over to the owner. Finally, the vessel was sent for sea trials with no loss of speed detected.
If you suspect abnormality in your propeller or any other part of your vessel, we are ready to assist. Besides propeller repairs, we also perform PBCF installations, renewal of scrubber pipes or any defect to your underwater hull or components. With Dive Marine’s vast range of in-house capabilities and global presence, we can provide integrated tailored solutions, quick mobilization and round-the-clock service support.
Contact us for more information. Our experienced team is ready to assist you:
[email protected] (HQ)
[email protected] (Europe)
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Eugene’s responsibilities include business development and performance of the company’s business. He has spear headed the diversification of businesses and developed the various subsidiaries within the Group.