For generations, we have delivered ship designs to service oil and gas installations in the world’s harshest sea areas. Offshore wind is a new segment in the offshore family, and the knowledge of how the weather can impact the vessel is of great value when developing designs and solutions for offshore renewables.
Service and assistance vessels
The ‘Windea La Cour’ was the first of the new breed of service and operation vessels (SOVs) entering the market. Recently awarded the 'Offshore Renewables Award', the 88 metre-long vessel of the ULSTEIN SX175 design is operated by Bernhard Schulte Offshore and contracted by Siemens. She commenced work on the large, 150-turbine Gemini wind farm 85 kilometres offshore the Netherlands in September 2016. Performing wind farm operations, the vessel’s main task is to transport and accommodate service technicians and to transfer them safely over to the wind farm installations. Her sister vessel, the 'Windea Leibniz', was delivered on 28 February 2017, and is also contracted by Siemens for work off the coast of Germany.
The first X-STERN vessel caused attention
The X-STERN is one of Ulstein’s many innovative contributions to the offshore wind segment. Placing the stern to weather reduces pitch motion and substantially lowers the required power in station keeping compared to bow into the weather. An intriguing side effect is the ability to keep high backwards speed. Windea La Cour, being the first vessel with an X-STERN, raised attention whilst on sea trials due to her high backwards speed. With a backing speed of 12.1 knots, close to the forward speed of 13.95 knots, the vessel is very flexible when moving around in the wind farm, and it does not matter where the weather is coming from or where she is heading next. The vessel is also carrying the X-BOW, a similar design for the bow. By lowering the acceleration levels of the bow and stern, the design minimises slamming impact.
The sister vessel, ‘Windea Leibniz’, will be starting work in April 2017 for Siemens on the Sandbank offshore wind farm outside Germany.
The bow and stern designs improve the sea-keeping abilities and eliminate abrupt stops from head seas. The vessels can easily go either way, and their nimbleness and flexibility make them ideal for working close to the offshore wind farm installations.
First dedicated SOV delivered in 2014
The first dedicated SOV developed by Ulstein, the ‘Siem Moxie’, sported several new features, including Voith Schneider propulsion and the X-BOW hull, a new type of crane and capability for installation support. Operated by Siem Offshore Contractors, she has been working together with the installation vessel ‘Siem Aimery’ in a ‘Siem Duo’ during the installation of the inter-array grid cable, as well as the foundations and the offshore substation for the 54 wind turbines, in the Nordsee One Offshore Wind Farm.
Equipped with a motion-compensated ‘Walk-to-work’ gangway, the vessel reported more than 8,000 personnel transfers at the Nordsee One farm. In the period from her delivery in April 2014 till September 2016, the vessel had an established track record of over 30,000 successfully executed personnel transfers, proving her capability as one the most advanced, safe and efficient service operations vessels available in the market.
Offshore wind farms are being established further from shore, and more offshore wind farm work could be carried out by monohull vessels, including foundation installation.
Acta Marine recently ordered the construction of a Construction Support Vessel (CSV) for the offshore wind industry from Ulstein Verft. The CSV can take on assignments in commissioning and construction in the offshore wind farm installation phase, and provide Walk-to-Work transfer of personnel and cargo.
One of the design areas at Ulstein specialises in offshore heavy-lift. Given the trend in the industry for even bigger wind turbines, larger installation units will be required or different installation methodologies.
Ulstein has started to work on jack-up designs, one of which includes a jack-up vessel capable of lifting 1,500-1,800 tonnes, both while in a jacked-up position and while afloat. More about floating and large jack-up installation.
When Ulstein recently entered into a cooperation with SeaOwls, an expert in jack-up technology and engineering, product director Edwin van Leeuwen at Ulstein stated that the combination of the two will “lead to a development of a novel jack-up concept with an aim to serve the future needs of the offshore wind industry. The new concept, dubbed SOUL, will be scalable and suitable for various crane sizes, variable loads and deck lay-outs.“
The design driver is to significantly increase the efficiency compared to existing units in the market, both in logistical lay-out as in pay load capacity. The jacking technology is considered the most critical element for a jack-up and for SOUL, Ulstein will make use of existing and proven jacking systems.
The two partners have come up with a new layout including number of alternative solutions that will significantly change and improve the installation of offshore wind turbines. “For installation work, especially for the foundations, the most effective tool is a floating platform. It makes installation faster as it is less restricted by jacking operations. Then, it makes sense to install the nacelle and turbine blades from a jack-up, as it has more precision high up,” says van Leeuwen.
Cable laying operations
The LX109 cable lay shipdesign is a high-capacity cable lay vessel with compact dimensions, dedicated for export power cables for the offshore wind industry. Implemented in open top vessel design is the patent-pending ULSTEIN Cable Arch system, which results in a total of 12,500 t of power cable that can be laid as one single piece.
Rock installation services
Ulstein also provides the engineering services and hardware solutions for vertical and inclined fall-pipe systems for subsea rock installation. One such vessel is the ‘Bravenes’ subsea rock installation vessel, currently under construction at the Sinopacific's Ningbo yard for Van Oord. This vessel is suitable for installation of a wide range of rock sizes through a fall pipe at the side of the vessel. With a deadweight of 14,000t, a length of 154 metres and a beam of 28 metres, the vessel can operate in water depths of more than 600 metres.
Windlifter turbine installation
The Windlifter™ is a system which is designed to transport and (de-)install completely pre-assembled offshore wind turbines – complete with nacelles and blades - in single-lift installation for bottom fixed foundations. The system comprises a storage and handling system for multiple turbines for efficient transport, which is linked to a mechanical system to skid the turbines safely and fully controlled from the vessel onto the foundation. The concept has been designed as a modular system to allow flexible utilisation of available vessels.
In 2015, a customized version was accepted as one of the winner’s in the Statoil innovation campaign, the Hywind Installation Challenge. In the Statoil campaign, it was adopted to work with the floating Hywind foundation.
Handling & Lifting equipment for offshore renewable energy sector
Ulstein can provide concept, basic and detail designs, dynamic assessments, purchasing and manufacturing of hardware for lifting and Handling equipment in offshore wind.
Besides the design process Ulstein can also provide services in assembling, installing and commissioning of equipment packages onshore or offshore. The design philosophy for our lifting equipment is to keep the lifting tools a mechanical system, with good quality production and a competitive price. The release of the lifting tools can be performed remotely or locally by means of mechanical release eliminating the downtime risk related to (hydraulic) system failure or human error. Hydraulics and electrical systems are used in the handling equipment to perform the operation as cost effective as possible, but with the same design philosophy in mind
Pile Gripper Frames
The industry’s two largest pile gripper frames have already been in use for several years at two different jack-up vessels. The gripper guides the mono pile foundation during lowering onto the seabed. After touchdown, the Pile Gripper Frame is used to restrain the foundation and adjust their inclination angle within the required verticality. After installation of the mono pile foundation, the frame fully retracts to create sufficient space for the installation of a transition piece on top of the foundation in a single jack-up cycle. The frames reduce the number of jack-up cycles and the risk involved in these operations, and this contributes to the optimisation of the offshore activities.
Pile up-ending and lifting
Our tools for up-ending and lifting piles engage at the top of the pile, supporting them from horizontal to vertical positions. This way of handling reduces the risk involved in pile up-ending, and contributes to the safety and efficiency of the offshore operations. The design of the Ulstein Pile Upending Frame ensures the balanced support of a (mono)pile throughout the entire up-ending operation.
The product range of flange lifting tools has been developed to lift all types of objects that can be lifted and handled from its top flange. This enables the lifting and installation of a full range of flanged objects typical for offshore wind construction, including transition pieces, tower sections, jackets or monopiles.
The next natural step in increased operability will be motion-compensation. Awarded the IRO Innovation Award, the ULSTEIN COLIBRI™ crane add-on is a compact and efficient 3D motion-compensated handling system to increase vessel operability, enabling smaller and more cost-effective vessels to be used in harsher weather conditions. The system is very flexible, as it can be mounted on the tip of a crane as a new-build option, or as a retrofit.
Heavy skidding systems and blade handling equipment are also focus areas to Ulstein. We are working on designing skidding systems up to 2,500t per unit and providing a reliable solution for underwater skidding. Blade handling equipment will be a focus point for our future portfolio and the design of this equipment will be done together with blade manufacturers.