A leading designer of vessels and jack-ups for the offshore renewables sector has developed a new design tailored to the needs of the offshore wind installation market.
Ulstein Design & Solutions’ Ulstein J102 heavy lift jack-up is the latest addition to its X-Jack series and is intended as a fit-for-purpose, cost-efficient, future-proof wind turbine installation vessel.
Ulstein Design & Solutions product manager Ko Stroo said of the new jack-up, “We see floating vessels as the preferred solution for foundation installation, whereas self-propelled jack-ups are the best tool for installing wind turbines.
“With the Ulstein J102 we have developed a cost-effective design with a crane capacity of up to 2,500 tonnes and hook height of 160 m above deck. This will allow contractors to efficiently carry and install four 15-MW turbines in a round trip.”
The key to the X-Jack design is its patented layout with a simple cruciform primary structure to achieve weight savings of 10-15% and create the most direct load path during preloading operations.
Positioning the jack-up’s legs wide apart in a square pattern results in efficient use of available deck space, at the same time effectively counteracting crane overturning moments. This also creates more body around the legs, enabling the use of large spud cans to reduce loads on the seabed.
The crane is fitted around the stern leg on the centreline. No ballast water is needed for lifting as the vessel is naturally balanced. Large spud cans reduce bearing pressures on the seabed and the vessel’s beam enables floating lifting operations. Last, but by no means least, the designer says the new unit also has increased propulsion efficiency as the wake of the spud cans does not interfere with thruster inflow.
The Ulstein J102 has a length of 145 m, breadth of 88.4 m, depth of 11.0 m and can accommodate 120 people. It can operate in water depths of up to 65 m and has a free deck area of 6,500 m2 and variable deck load of 10,500 tonnes. It can transport and install eight 8-MW turbines or four of 15 MW. The main crane can lift 2,500 tonnes at a radius of 39 m and 1,250 tonnes at 65 m.