Supporting DEME Offshore, the company deployed its K-3000 class heavy lift vessel Fairmaster to transport 141 monopiles (MPs) and 131 transition pieces (TPs) from Rostock, Germany and Aalborg, Denmark to Eemshaven, the Netherlands. The MPs were 8.5 to 9.5 m (28 to 31 ft) in diameter and weighed up to 1,285 metric tons (1,416 tons).
The 152.9-m (501.6-ft) long heavy lift vessel, with two 1,500-metric ton (1,653-ton) cranes, provided a flexible deck layout. The company could offer three different loading configurations without intermediate standby periods for re-configuration: five MPs loaded on deck and in the hold, six TPs and three MPs, or three TPs and four MPs.
Jumbo’s project manager Maarten De Gruyter said: “This engineered flexible solution made it an extremely efficient vessel for the project and is one of the things we’re most proud of – it helped us conclude the project scope within just 37 voyages in a period of just under 12 months.”
The vessel’s multiple loading configurations allowed the company to adjust to its client’s planning, which was linked to the delivery sequence from fabrication yards.
“We had close cooperation with DEME Offshore with regards to scheduling, and we could handle many changes to the sailing sequence,” De Gruyter said. “Ultimately, this meant that we could carry more equipment within less time.”
According to De Gruyter, the execution efficiency was due to numerous aspects. “During the planning phase, we designed and engineered the MP saddles and TP grillages to deliver our proposed vessel efficiency. We used inlays in the saddles to accommodate the different diameters of the MPs. The clearances were tight: sometimes 50 cm or less between components,” he said. “We also installed project-specific lifting lugs on the deck hatches to speed up loading and unloading operations.”
As part of reducing the environmental footprint of the construction of the Hornsea Two offshore wind farm, Jumbo was required to include a green initiative into its project execution. As such, the company chose to sail with Bio-Fuel Oil from GoodFuels. This product is expected to deliver 80-90% CO2 reduction versus fossil equivalents and contains no sulphur oxide emissions, the company claimed.
The Hornsea Two project is the largest number of MPs and TPs that Jumbo has ever shipped in a single contract and with one heavy lift vessel.
Jumbo’s commercial manager Boudewijn van der Garden said: “We converted the Fairmaster into a kind of ‘Swiss Army knife’ that provided an unrivalled heavy lift vessel intake of large diameter monopiles and transition pieces, but still with the flexibility required for the various lengths and diameters that were to be transported.”