When our client required 12km of inter-array subsea cable for a developing offshore wind project, the challenge was clear — the cable length was too short to justify traditional large-scale carousel transport. This presented significant commercial risks: potential demurrage costs on expensive installation vessels and delays at the loading port, both of which could impact the offshore construction schedule and project economics. To address these challenges, Harlyn implemented its tried and tested RoRo-based transport method, providing a safe, efficient solution that removed the need for double handling and minimised time alongside port infrastructure or high-cost vessels.
Applying a Proven Basket and RoRo Handling Method
Because the cable length did not justify full-scale carousel transport, Harlyn used its established method involving custom-engineered cable baskets optimised for shorter-length subsea cable handling.
The baskets were designed by Harlyn’s engineering team and fabricated by Marine Repair BV in the Netherlands. Each basket was engineered for secure spooling, structural stability, and sea-fastening efficiency to ensure full compliance with offshore transport requirements.
Once fabricated, the baskets were transported to Corinth, Greece, where Harlyn’s field team managed the spooling and loading operations. Using Harlyn’s own Self-Propelled Modular Transporters (SPMTs), the baskets were rotated and aligned for accurate cable spooling. The operation utilised Harlyn’s BCE equipment — a precision handling unit designed to manage cable spooling tension and control winding cable catenary geometry — ensuring the cable was loaded evenly and securely within each basket.
RoRo Efficiency – Eliminating Double Handling and Reducing Risk
With the cables spooled and baskets secured, Harlyn deployed its RoRo loading and discharge method, allowing the fully loaded baskets to be driven directly onto and off the vessel using SPMTs. This approach eliminated the need for cranes, avoided double handling, and dramatically reduced port turnaround time — directly mitigating demurrage exposure for the client’s installation and transport vessels.
For this project, Harlyn chartered the Western Rock, a Hartman Seatrade vessel with a versatile deck configuration and ramp access ideal for RoRo operations. The vessel’s flexibility enabled rapid loading and discharge, reduced interface risk, and ensured safe, predictable transfer from Greece to the U.S for the cable baskets.
Safe and Reliable Delivery Across Three Continents
Over a 96-day charter, the Western Rock supported this and other Harlyn projects . The project achieved full compliance with the client’s technical and offshore transport standards, and the cable was delivered on time, intact, and ready for offshore installation.
Results
This project reaffirmed the efficiency and reliability of Harlyn’s proven RoRo basket transport method for short-length subsea cable movements:
- Mitigated demurrage and port delay risks for the client’s high-value vessels.
- Eliminated double handling, reducing cable damage risk and port time.
- Delivered a cost-effective alternative to carousel-based transport methods.
- Ensured full compliance and technical assurance from spooling to final delivery.
- Meant additional onshore storage medium wasn’t required
Harlyn Testimonial
“This project demonstrated how applying a proven method can remove unnecessary risk and delay,” said Hamish Adamson, Managing Director of Harlyn. “Using our own SPMTs, BCE equipment, and RoRo process, we ensured the operation ran smoothly and safely, with complete control from start to finish.”
