Seajacks Scylla is one of the world’s largest and most advanced offshore wind farm installation vessels. Mark Hayward, jack-up and geotechnical manager, outlines the role of DNV GL’s Noble Denton marine services in the vessel’s journey to operation.
In today’s challenging industry conditions it seems there are few jack-up vessel design, construction and deployment projects being completed on schedule and to budget. The state-of-the-art Scylla wind turbine foundation and installation vessel not only boasts that accolade, but also lays claim to possessing the largest deck space, leg length and lifting capacity in the wind industry today. The newest member of the Seajacks UK Ltd fleet was specifically designed for deeper water and larger wind farm components. She was completed on schedule in November 2015 and is currently working on her first job at Veja Mate offshore wind farm in Germany.
DNV GL’s Noble Denton marine services team provides technical analysis across the fleet of Seajacks UK Ltd, a world-leading offshore installation and maintenance contractor in the offshore wind, and oil and gas sectors. In the case of the Scylla, the company has been involved in the vessel’s journey to operation from the early stages of the project. Experts from the company’s offices in London, UK, were appointed to review Scylla’s design capability against proposed locations in January 2015; they have since played a key role in verifying the new vessel’s capabilities to satisfy marine warranty requirements, and continue to provide assessment, metocean and location approval support during project tenders.
“For the Veja Mate offshore wind farm, for instance, this has included providing marine warranty surveys to ensure that the new vessel is able to operate in the territory. We conducted analysis of soil conditions in the installation zone and assessments of port locations, global stability and structural capability checks for both storm loading and key operational loading conditions” explains Mark Hayward, jack-up and geotechnical manager, DNV GL - Oil & Gas.
Located 95km northwest from the island of Borkum in the German North Sea, Veja Mate will comprise 67 6MW Siemens turbines. Installation has started at the site this spring and involves loading components and equipment at the quayside by crane in order to shuttle back and forth between the port and installation zone. Five monopiles have been installed, and once fully operational in 2018, Veja Mate will produce enough power to meet the demand of around 400,000 German households.
A vessel for the future
Built by Samsung Heavy Industries in Korea, the Scylla has pushed new boundaries in installation jack-up capabilities. The vessel is able to sail at speeds of 12 knots or over, has a 1,540 ton (t) leg-encircling crane, and is outfitted with 105 metre (m) long legs which give the ability to install components in water depths in excess of 65m – in other words, North Sea conditions. She is also the world’s largest vessel with a useable deck space of 4,600m² and 8,800t of available variable load.
“The Scylla has been designed specifically to work in harsher environments and to carry both heavier loads and deck space for more components per outing,” explains Mark. “Given the current trend for windfarms to be located further offshore with significantly increased transit times, this is important in terms of driving efficiencies - simply put, the Scylla is able to carry more, which results in fewer trips, but also its crane capacity and capability means it’s able to install the largest monopiles and turbine components more effectively.”
In addition to Veja Mate, DNV GL’s Noble Denton marine services team will be supporting tenders for future deployments by providing site-specific assessments to ensure that the vessel can be used safely and effectively in the designated installation zones. For example, assessing seabed and storm conditions, as well as verifying that the vessel is capable for its intended use.