Greater Gabbard takes Jumbo step forward

Jumbo Javelin, Jumbo Offshore’s DP2 vessel, has been used to install the first 20 in a series of 110 transition pieces at the offshore wind farm. Jumbo Javelin is equipped with two 900t Huisman mast cranes that can lift 1,800t in tandem onshore, and 1,100t in tandem offshore. The cranes maintain their maximum lifting capacity at 27.5m outreach on the portside, and 27.5m outreach to starboard. Jumbo Javelin is one of four J1800-class vessels in Jumbo Offshore's installation fleet.

The 270t transition pieces were loaded onto Jumbo Javelin at the Port of Vlissingen, the Netherlands before the vessel sailed, with open hold, to the installation site. There, Jumbo Javelin positioned itself on dynamic positioning and lifted the first transition piece onto its monopile.

After levelling the transition piece to its final position, the space between the transition piece and the foundation pile was filled with grout to fix it permanently.

This installation work, Jumbo Offshore said, is the first time transition pieces have been transported and installed using a free floating vessel on dynamic positioning in one trip.

The Jumbo Javelin uses its DP2 system to create a working environment in which transition pieces can be installed in wave heights up to 1.5m.

Jumbo Offshore also utilised two lifting compensators, Cranemaster and Jumbo Compensator. This, it said, helped reduce the influence of vertical forces on the crane, akin to how heave compensation reduces the motion of a load in the crane.

Jumbo Javelin's sister vessel, Fairplayer, has recently been upgraded to include a deepwater deployment system. This combines the vessel, the cranes and a pair of deepwater winches to allow 1,000t installations at 1,000m depths, 600t at 1,700m and 200t at 3,000m.