This project is the first 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.

Prysmian Cavi e Sistemi Energia SrL subcontracted Assodivers Ltd, to protect the Pole 1 cable from the landing points up to water depths of 680m. In 2010, Assodivers was awarded a direct contract by Terna - Rete Elettrica Nazionale SpA to protect the Pole 2 cable, again up to the same water depth on each side.

In Pole 1, the protection sequence was divided into two activities. First activity required the operations to be executed by Prysmian's vessel 'Giulio Verne' and involved the protection of the electrodes both in Nettuno and Sardinia by jetting. The second phase was executed by utilizing MPSV 'Argo I' DP support vessel and involved the protection by trenching of the electrode in Sardinia and the protection of the HVDC cable in Nettuno and Sardinia areas by both jetting and trenching.

Both jetting and hard soil trenching processes were required to bring the cable protected at the required levels. All jetting operations were carried out with the use of our deep water ROV jetting vehicle 'Venom 3k-450T' while trenching activities were carried out using 'AssoTrencher IV'. In total 238km were protected across the cable route, of which 194.5km were protected by means of jetting and 43.5km by means of trenching.

Project Specifications

SAPEI - Pole 1

Prysmian Cavi e Sistemi Energia SrL
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:
43,450m @ 0.5m
Jetting Length & Burial Depth:
194,450m @ 1.0m
Tyrrhenian Sea, Italy
Max Water Depth: