A 236.80 meter long and 52.00 meter wide crane ship ordered by Belgium based Jan De Nul Group at the CMHI Haimen Shipyard in China last November (see earlier story) will have a full Schottel propulsion package. To be called Les Alizés, it is aimed primarily at installation of new generation offshore wind farms and will be equipped with a crane with a lifting capacity of 5,000 tons and was ordered just six months after Jan De Nul’s ordering of a giant offshore installation jack-up vessel, the Voltaire, at China’s COSCO Shipping Heavy Industry shipyard.
The Schottel package being supplied for Les Alizés comprises four rudderpropellers, two retractable rudderpropellers and two transverse thrusters, ensuring optimal propulsion efficiency as well as maximum maneuverability.
“Thanks to her dimensions and her impressive lifting and loading capacities, ‘Les Alizés’ will be able to load out, transport and install multiple units of the largest and heaviest wind turbine foundations. In addition, as a crane vessel that floats, it will be able to install heavier and larger foundations into deeper waters and in more challenging seabed conditions,” says Philippe Hutse, Offshore Director at Jan De Nul Group. “To meet these demanding tasks, we are pleased that the reliable propulsion solutions from Schottel have been selected.”
MAXIMUM PROPULSION EFFICIENCY
The main propulsion system of the crane vessel consists of four electrically driven Schottel Rudderpropellers type SRP 610 FP – each with an input power of 3,000 kW and a propeller diameter of 3.30 m – installed at the stern. With this setup, Les Alizés will achieve a maximum speed of 13 knots.
To ensure precise position keeping in DP service, two Schottel Retractable Rudderpropellers type SRP 610 R (3,250 kW each and a propeller diameter of 3.00 m) and two Schottel Transverse Thrusters type STT 7 FP (2,600 kW each and with a propeller diameter of 2.79 m) are installed in the bow of the vessel. The retractable units are fitted with an 8° downwards-tilted propeller shaft in order to reduce thruster-thruster and thruster-hull interactions and increase propulsion efficiency.
The tunnel thrusters are designed so that they can be serviced while the vessel is afloat.
REDUCED DOWNTIME, REDUCED LIFECYCLE COSTS
As part of an extended drydocking program, “Les Alizés” will be able to prolong its dry-docking period from 5 to 7.5 years. To make this possible, the vessel will be equipped with a state-of-the-art condition monitoring system from Schottel. It offers automatic, 24/7 on-board surveillance of the propulsion units – even in full offline mode. The permanent vibration monitoring of the system and automatic trend observation of the monitored data allows for thruster maintenance based on their current condition. This helps to avoid unnecessary part exchanges and downtimes.
GREATER ENVIRONMENTAL PROTECTION
The 236.80 meter long and 52.00 meter wide crane vessel will be environmentally compliant thanks to the on-board integration of the same advanced emission control technology found on all other low-emission vessels in the Jan De Nul fleet. It will carry a Cleanship NDO7 label and a Green Passport EU label.
The vessel’s thrusters will be equipped with the patented and DNV-GL type-approved Schottel LEACON sealing system. This system ensures continuous leakage control of the seals and prevents water from entering the gearbox and, of even greater importance, oil from escaping into the seawater. Considered a non-oil-to-water interface, the system complies with the VGP regulations of the U.S. Environmental Protection Agency (EPA) without the need to use environmentally acceptable lubricants (EALs).
The new crane vessel is scheduled to enter operation in 2022.