Our field of expertise
Engineering the OSV Elena cable repair mobilization
When a subsea cable at the Burbo Bank Offshore Wind Farm off the coast of Liverpool required fixing, N-Sea needed a fast, reliable mobilization solution. They turned to Saltwater Engineering to deliver the complete engineering package for the Offshore Support Vessel (OSV) Elena. A bare vessel that we needed to transform into a fully operational cable repair ship.
The challenge was clear: we had to determine if the vessel could safely accommodate the heavy cable repair equipment, design all custom foundations and sea fastening arrangements, and support the mobilization within a demanding project schedule. Working closely with N-Sea, Saltwater Engineering provided the full engineering package, construction support, and on-site assistance to ensure the vessel was ready for operations on time.
From bare vessel to cable repair ship
To execute the cable repair campaign, the OSV Elena required a wide range of specialized equipment, including a cable carousel, loading tower, tensioner, roller boxes, cable chute, winches, and a work-class remotely operated vehicle (WROV) launch system.
We kicked off the mobilization process with a detailed assessment of the vessel’s deck structure. Our engineers evaluated whether the existing deck could withstand the operational loads generated by the repair equipment. Saltwater performed comprehensive structural calculations to verify deck strength and determine the exact requirements for foundations and sea fastening arrangements.
Using 3D scanning to reduce installation risks
To maximize accuracy during the engineering phase, Saltwater Engineering performed a full 3D scan of the vessel. The scan provided an exact digital representation of the available space and existing structures on board.
Using this data, our engineers identified and resolved potential clashes during the design phase, allowing us to optimize equipment positioning before fabrication even started. While offshore mobilizations inevitably encounter unforeseen challenges during physical construction, our 3D model significantly reduced installation risks and boosted overall project efficiency.
Designing custom foundations and a mezzanine deck
Based on our structural analyses, Saltwater Engineering designed the custom foundations and sea fastening solutions required to secure all equipment to the deck. We produced detailed engineering drawings specifying equipment locations, foundation arrangements, and precise installation requirements.
Beyond the cable handling system, the project also required a dedicated solution to deploy a WROV. To facilitate this, our team designed a custom mezzanine deck capable of supporting both a winch and an A-frame launch system. This additional structure created the necessary workspace on board while meeting all structural and operational safety requirements.
Full engineering scope and project support
Within this project, Saltwater Engineering carried out a broad scope of work. We performed FEM analyses to verify the structural strength of both the A-frame and the deck. In addition, we developed construction drawings, along with all required outfitting drawings for items such as stairs, platforms, and railings.
We also prepared demolition drawings, as well as drawings for reinstating the structure after removing existing components. This included modifications such as relocating doors, bollards, and stairs.
Based on a 3D scan, we verified whether the deck is sufficiently level for the installation of the foundation. In addition, we developed a load test arrangement and the corresponding test protocol in close collaboration with Geoquip.
During the construction phase, Saltwater Engineering also provided construction support, working closely with the yard to address questions and to effectively implement any changes arising during execution.
Supporting construction and mobilization
Following the engineering phase, Saltwater Engineering remained closely involved throughout fabrication and mobilization.
Our team supplied the cutting files for steel fabrication and prepared detailed material inventories to streamline procurement and logistics. This ensured that the metal processing company ordered and received all necessary materials in time for construction activities.
As project engineers, we also provided vital on-site support during the mobilization itself. Because we developed the engineering package from the ground up, we could quickly answer drawing-related questions, resolve unexpected issues on the spot, and deliver practical solutions whenever construction challenges or minor clashes arose.
Managing a tight schedule
Planning was the biggest challenge. Repair campaigns cannot always be planned far in advance, but the mobilization still has to be completed before the vessel leaves port. That meant the engineering, procurement, and fabrication all had to stay on schedule.
Despite these challenges, close collaboration between N-Sea, the shipyard, and Saltwater Engineering ensured that the mobilization was completed successfully, and the vessel was ready for the cable repair campaign.
Result
By combining structural engineering, 3D scanning, foundation design, fabrication support, and on-site mobilization assistance, Saltwater Engineering successfully transformed the OSV Elena into a fully operational cable repair vessel for the Burbo Bank campaign.
This project highlights our ability to deliver comprehensive mobilization engineering packages under demanding schedules, supporting offshore contractors with practical, efficient, and reliable engineering solutions from concept through execution.
