You`re gonna need a bigger crane…”
Offshore wind turbines are reaching new heights both literally (meters), and figuratively (megawatts). As the demand for larger turbines surges, so do the challenges faced by offshore installation contractors, which need to come up with bigger vessels, and, consequentially, bigger cranes for those vessels.
Jan De Nul's Voltaire jack-up sporting Huisman's largest delivered LEC to date. Credit: Jan De Nul (File image)
When the assignment to produce a piece focusing on heavy-lifting cranes and deck machinery for OE was taken on, Huisman immediately stood out as the company best suited for coverage in this space, especially given its innovation in Leg Encircling Cranes (LECs). A search for "Huisman" on OEDigital.com yielded around 172 articles, with a significant portion of them being recent reports about Huisman successfully securing orders for Leg Encircling Cranes designed for jack-up offshore wind installation vessels. These orders have been received from top-tier offshore wind installation service providers like Van Oord, Cadeler, Havfram, Eneti, Dominion, DEME Offshore, Jan De Nul, and Fred. Olsen Windcarrier.
To delve deeper into these offshore cranes, the focus turned to Cees van Veluw, an expert at Huisman with a background in structural and mechanical engineering. Van Veluw's journey at Huisman began in 2005, and he has progressively advanced to his current role as the Product Director of Cranes, which he assumed in July 2022. His responsibilities encompass supporting the sales team through proposal provision and spearheading new technical developments related to offshore cranes. Cees van Veluw provided insights into Leg Encircling Cranes (LECs), shedding light on their significance and functionality. LECs are specifically designed for installation on jack-up vessels, which are self-elevating units featuring legs that can be lowered to the seabed. Through a jacking system, these vessels are raised above the water, effectively transforming into stable platforms for wind turbine installation.
The concept of a Leg Encircling Crane is fairly self-explanatory. As Van Veluw explained, these cranes encircle one of the jack-up vessel's legs. This configuration has distinct advantages, particularly in terms of conserving operational space. By aligning the crane around the central axis of a leg, valuable space on the vessel is optimized. This design innovation was born out of the question: "Can we place a ringer crane similar to the PTC-35 we supplied to Mammoet on a jack-up vessel?" This initial idea evolved through refinement and adjustment, resulting in the Leg Encircling Crane design that Huisman has become known for. These cranes have proven highly popular for installing wind turbines and foundations. Notably, all of Huisman's LECs are fully electric, which confers benefits such as operational precision, reduced noise levels, and elimination of the risk associated with hydraulic hose failures. Customization is a hallmark of Huisman's LECs, as they are tailored to meet the unique requirements of each client, whether it's an offshore wind installation firm or a shipyard constructing a Wind Turbine Installation Vessel (WTIV). This customization encompasses various aspects, including hook configurations, boom lengths, operating speeds, paint systems, and cabin layouts, among others.
The process of delivering an LEC typically spans two to two and a half years, contingent upon factors like features, timing, supply chain dynamics, and the extent of customization. Additionally, the installation of these large cranes onto vessels involves careful coordination with
vessel owners and, if applicable, shipyards. Huisman has invested in a significant asset—the Skyhook crane in its Chinese facility—to facilitate smoother crane installation.
The offshore wind industry's evolving landscape demands larger and more capable equipment. Van Veluw emphasized that offshore wind turbine installation vessel operators increasingly require larger cranes to accommodate the growing dimensions of wind turbines. These demands have led Huisman to develop LECs with ever-increasing lifting capacities and boom lengths. Recent examples include Huisman's successful delivery of a 2,200mt LEC to Keppel AmFELS shipyard in Texas for integration onto the first Jones-Act compliant WTIV, as well as the installation of a 3,200mt LEC on Jan De Nul's Voltaire jack-up vessel, setting a new record for the world's largest installed LEC. Huisman's proactive approach extends to anticipating future needs. The company has a model prepared for a 5,000t LEC version and is considering the integration of larger jacking systems to support even bigger cranes. The industry's shift towards ever larger turbines—upwards of 15MW—underscores the need for correspondingly robust crane technology.
In closing, Van Veluw emphasized that while there might be limits to crane size, Huisman's current designs still have room for growth, both in terms of lifting capacity and boom length. As wind turbines continue to increase in scale, crane technology will play a pivotal role in facilitating their installation, and Huisman appears poised to lead the way in meeting these evolving demands.