Cases

GNSS960 RTK precision 25 miles Offshore

About GNSS960 RTK precision 25 miles Offshore


Dutch contractor Van Oord Dredging and Marine Contractors bv (Van Oord) has been awarded the contract for the engineering, procurement and construction of the first part of the Belwind offshore wind farm project. The wind farm will be constructed on the Blight Bank, 46 kilometers off the coast of Zeebrugge, Belgium. Van Oord subcontracted the placement of the turbine foundations to Ballast Nedam. The HLV Svanen was dedicated to the project to place the monopiles during the North Sea autumn and winter conditions.

Strict criteria for final pile head elevation, within 15 cm range around target height, the floating operation and the sea state conditions called for a non standard solution. In order to achieve the criteria the accuracy of the positioning system should be well within 10 cm (95% accuracy).

Stema Systems provided a dual set, primary and back-up, GNSS960 receivers that were connected to the ships ethernet. Via satellite communication and dedicated bandwidth VRS corrections from the Qpos server were retrieved. The absolute height information was real-time transfered to the pilehead by means of the Qinsy packaged feeded by a Ixsea Phins motionsensor/gyro and a total station.

The system provided very reliable position information throughout the project and no delay due to RTK position has occured over a period of 4 months. Achieved accuracy was well within the specifications.