TP seafastening & MP skidding and upending

Situation

Galloper offshore wind farm will be located 27km off the Suffolk Coast in the Thames Estuary, UK. GeoSea is responsible for the design, fabrication and installation of 56 steel monopile foundations, which will be driven into the seabed, to provide a solid base for each of the wind turbines. The monopiles being used for this project, are the heaviest that GeoSea ever installed, with weights in excess of 1100 tons. The installation of the foundations at the offshore site is scheduled towards the end of 2016.

Construction of the Galloper offshore wind farm project brings the UK a step closer to achieving significant clean energy and carbon reduction benefits. The estimated annual production is expected to be equivalent to the domestic needs of approximately 336,000 average UK households. To achieve this target, 56 turbines, each with a 6 MW capacity,will be installed.

Challenge

For the Galloper offshore wind farm GeoSea sub-contracted the production of monopiles and transition pieces to  Sif Group and Smulders. The monopiles for this wind farm vary in size and weight, lengths upto 85 metres with a max diameter of 8.5 metres and weight upto 1.100 tonnes. Due to the size and dimensions of the monopiles in combination with the travel time a smart solution was needed to take on more foundation parts whilst still keeping as much free space on deck of the GeoSea installation vessel 'Innovation' as possible.

Solution

For the seafastening application of the transition pieces Holmatro developed double acting locknut cylinders that fixate the TP’s to the deck by means of a special designed clamping system. To be able to take on more monopiles a clever system was designed that allows GeoSea to take on 4 monopiles per time, that reduces handling by skidding these MP’s in position for upending and that is able to also do the upending part of the process. For this MP skidding and alignment system Holmatro developed and supplied special locknut cylinders with stroke sensors which are used for the alignment during skidding and for fixation during transfer.

Would you like to know more about this project? Contact us via e-mail industry@holmatro.com or call +31 (0)162 751500.