This project is the second phase of the SAPEI project, a power link between Italy mainland to Sardinia via a 500 kVDC circuit, consisting of two main cables Pole 1 and Pole 2 and respective anode and cathode cables at both ends of the link.

The SAPEI HVDC undersea link is able to deliver power from the island of Sardinia to the Italian mainland in order to strengthen the power grid near Rome. At that time, it was considered to be one of the largest links ever produced worldwide not only in regards to its depth, but also to its length. The maximum depth the submarine cables lie below the sea level is 1,600m, while its total length underwater is 420km and on land 15km.

Terna - Rete Elettrica Nazionale SpA, awarded a direct contract to Assodivers Ltd, to protect the Pole 2 cable from the landing points up to water depths of 680m. In 2008, Assodivers was subcontracted by Prysmian Cavi è Sistemi Energia SrL to protect the Pole 1 cable, again up to the same water depth on each side.

In Pole 2, both jetting and hard soil trenching processes were required to bring the cable protected at the required levels. Furthermore, based on the laying schedule of the project and in order to minimize the time that the cable was left unprotected between the laying and the final protection, Assodivers had performed the utilization of two support vessels operating in parallel at a certain stage of the project.

Both SPS 'Argo I' and SPS 'Astrea' DP support vessels were used on the different phases of this project. All jetting operations were carried out with the use of our deep water ROV jetting vehicle 'Venom 4k-600T' while trenching activities were carried out using 'AssoTrencher IV'. In total 210km were protected across the cable route, of which 165km were protected by means of jetting, 45km by means of trenching and for a small portion of 135m mattresses were applied by using our specialized frame 'AssoMat I'.

Project Specifications

SAPEI - Pole 2

Assodivers Ltd.
Cable Type:
500kV HVDC
Cable Weight:
Shallow water: 34.6kg/m Deep water: 25.9kg/m
Cable Diameter:
Shallow water: 118mm Deep water: 119,2mm
Service Provided:
Offshore Protection
Terna - Rete Elettrica Nazionale SpA
Trenching Length & Burial Depth:
45,000m @ 0.5m
Jetting Length & Burial Depth:
165,000m @ 1.0m
Alternative Protection:
Mattresses: 135m
Tyrrhenian Sea, Italy
Max Water Depth: