Underwater propeller repairs: now class approved

March 25 2024

A damaged propeller can lead to reduced performance, increased fuel consumption, and overload on ships’ engines. Cropping is one solution, but it’s only temporary and requires re-work by welding on new blade material in a workshop. Furthermore, reducing propeller blade surface will result in loss of efficiency and reduced sailing speed. It can even lead to rejection of the propeller if cropping is done beyond certain limits.

To avoid these costly risks and offer customers an alternative, UPE has joined forces with propeller specialist Plug & De Boer to develop a hydraulic press for cold straightening of bent propeller blades.

How it works

Prior to any repair, a detailed inspection followed by a repair proposal plan is submitted to the stakeholders for approval. Then two dive-techs, communicating with each other and the surface team position and use the hydraulic tool in such way that the hydrodynamic balance and efficiency of the propeller is restored to its maximum. A propeller repair specialist from Plug & De Boer guides and supervises the operations.

This repair method is possible for excessively bent blades. It is considered a permanent repair and a very good alternative to cropping, where blade tips are simply cut off. However, cold straightening always holds the risk of cracking or breaking during the repair process. However, with the experience of the UPE team and its partners, this risk is reduced to the absolute minimum.

Class approved

Recent underwater straightening operations have led to approvals from IACS-members Lloyd’s Register and NKK. A procedure for underwater propeller cropping as a temporary repair has been approved by class ABS.

Global coverage

UPE’s specially designed cold straightening propeller repair tools – nicknamed Pacman – are located in the Netherlands (Rotterdam) and the Americas (Panama), but can and have been utilised all over the world.

The unique cooperation of UPE, AEGIR-Marine and Plug & de Boer guarantee the required experience and skills to offer the complicated but time and money saving repair method of cold straightening. We are available around the clock and around the globe. Feel free to contact us when needed.