SAL Offshore’s main vessel, the DP-Class-II-equipped MV Lone with work-class ROV, has successfully installed a VOITH Hytide 1000-13 tidal turbine at Stavanger in Norway.

Coming directly from her previous employment on the Parbuckling Project (Costa Concordia), MV Lone proceeded to Stavanger to mobilise an ROV spread and project equipment. The mobilisation was completed in two-and-a-half days, at which time the vessel sailed to the Kirkwall / Orkney Islands in the north of Scotland to load a LARS (launch and recovery system) for the turbine. After conducting a HIRA (hazard identification and risk assessment) with all involved parties and a function test of the equipment, MV Lone departed Kirkwall for the EMEC (European Marine Energy Centre) test site to conduct DP trials and ultimately install the turbine.

The installation process required MV Lone to lift the tidal turbine from its transportation cradle on a barge and place it on the pre-installed foundation. Securely installed in the foundation, the turbine blades are some 14m below sea level.

Holding position in a current of five knots

Installing tidal turbines is very demanding for a vessel’s DP system, as the position has to be held in strong currents. In this case, there was a time slot for deployment only once every six hours during slack water. Installation took place at slack water, although there was still a one-knot tide running, and the vessel was also required to sit through the full flood, which peaked at a maximum current of five knots. The WROV served as a support to monitor the process underwater and also hooked up the controls.

For the subsequent commissioning test program, MV Lone remained on-site, holding her position in the current while still being connected to the turbine. After its successful commissioning, MV Lone returned to Kirkwall to de-mobilise the equipment.