
The world’s first underwater robot to repair ship hulls using friction stir welding has reached a milestone with the completion of the system’s concept design.

The RESURGAM project (Robotic Survey, Repair and Agile Manufacture)Funded by the European Commission and developed by 13 partners, it will eventually make it possible to repair a ship’s hull at sea, eliminating the need to go to dry dock.
With RESURGAM, responsive repairs can be performed remotely from anywhere in the world and is expected to save the industry time, money and make it safer by removing the need for specialized divers.
Engineers from Cumbria-based Forth have been appointed as the technical managers of the project. To date, the team has completed a Functional Means Analysis to determine all the features of the new tool, and completed a full option process to decide on the concept model. An initial concept design for the weld head and frame mechanics has also been completed and will be developed in the coming months.
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In a statement, Chris Downham, Forth’s Operations Manager, said: “The RESURGAM project is such an exciting initiative to be involved in and the input from companies from across Europe demonstrates the true power of collaboration, with each representative providing a unique set of skills for the project.”
Forth is tasked with designing a custom underwater friction rudder welder that can be mounted on the side of a ship’s hull and create a friction rudder weld in a vertical plane between a repair site and the defective part of the hull.
To secure the machine to the hull, the team designed a circular track frame to hold the welding head, which is attached to the hull via a frame using four R1000 solenoids, each of which must force 7.5 tons. and allow the weld head to provide the required force on the Z axis to continue welding.
The system will be tested at the company’s Deep Test Pond, one of the largest facilities of its kind in the UK.
Forth’s engineers will now begin a detailed design program using design risk assessment analysis to explore the features the robot needs and identify early design and functional complications.
Once the design has been completed, it undergoes a final assessment before moving on to the final stages of the project and fabrication of the system.
RESURGAM project partners include The Welding Institute; Lancaster University’s Joining 4 Innovation Center; Element Six (all in the UK); ACLUNAGA (Spain); AISTER (Spain); European Welding Federation (Portugal); University of Limerick (Ireland); TU Delft (Netherlands): STIRWELD (France); Engitec Systems International (Cyprus); and GISBIR (Turkey).