Jumbo Offshore’s engineers and the crew of DP2-vessel Jumbo Javelin have successfully installed their first Transition Piece (TP), off the UK’s south-east coast. This is the first time that a TP has been transported and installed with only one DP2 vessel. The installation trial included leveling and grouting operations and even the removal of the TP. With a workability for critical lifts in wave heights up to at least Hs = 1.5m, Jumbo Offshore is now able to deliver various installation services for offshore wind farms.
After loading the 255 tonnes TP in Flushing, it was transported to the offshore location. There, the Jumbo Javelin positioned itself on DP next to the monopile and lifted the TP from her lower hold onto the monopile. After leveling the TP to its final position, the grouting procedure was tested.
To give crew safe access from the Jumbo Javelin to the installed TP as well as efficiently guiding the grout hoses, the Ampelmann II was used. This ship-based, self stabilizing platform actively compensates all vessel motions to make offshore access safe and easy. In 20 landings, a total of 72 transfers were made to and from the TP. Furthermore, the Ampelmann supported the grout hose. Access and support is possible in wave heights up to Hs = 2.5 m.
It was the first time that a TP was placed on a monopile from a free floating vessel on DP. The whole operation was completed in approximately 24 hours and was performed as planned with respect to every detail: transportation, installation, accessibility of the TP, grouting and, importantly, safety.
The Jumbo Javelin is able to carry 9 TP’s at a time, each with weights up to 300 tonnes. All the TP’s can be stowed vertically in the hold of the vessel and transported to the offshore location. The ship is free floating and uses its DP2 system to create, amongst others, a working environment in which TP’s can be installed in wave heights up to Hs = 1.5 m. With a high transit speed of up to 17 knots, the vessel is well-equipped for wind farm installation work.
Using a DP positioned heavy lift vessel compared to the conventional method of moving and installing TP’s brings advantages. One: the vessel is used for transporting a considerable load. Two: fast transit to the installation site and the installation itself. Three: the relocation from one position to the next is a relatively fast one, as the vessel does not need to reposition anchors or jack up and down again.