Envy of the (Norse) gods

Heerema Marine Contractor’s new semisubmersible crane vessel is set to make waves. Elaine Maslin reports.

An illustration of the new NSCV.  Photos from Heerema Marine Contractors.

Norse gods do not come along that often. Yet, Heerema Marine Contractors (HMC) is working on one that will dwarf its mighty Thialf.

After three decades in service, the 14,200-tonne lifting capacity Thialf, named after Norwegian god Thor’s sidekick Thialf, is still the largest crane vessel in the world.

Now, however, it is set to get a yet-to-be-named big brother. The twin-crane concept for HMC’s new 20,000-tonne capacity semisubmersible crane vessel (NSCV) was unveiled earlier this year and work has already started on its construction. A first steel cutting ceremony for the cranes was due to be held in China on 1 July.

With it, HMC is making a statement, not only about the firm’s commitment to the heavy lift segment, including upping the limit for single platform lifts, but also, adopting a new crane design and opting for the vessel to operate on LNG.

“There is no heavy lift crane vessel of this size in the market today,” says Jan Pieter Klaver, HMC’s CEO. “We have plotted its size in relation to our new offices and, when you do this you do not see the new offices anymore. You start to see the Thialf as a small vessel in comparison. But, everything is relative.”

The NSCV will not only outsize Thialf, which will remain a key player in HMC’s fleet, it will also bridge a gap between heavy lift crane capacity and the floatover market, Klaver says. Potentially, he says, it could also work with Thialf.

“In our portfolio of lifting capability, this falls between the Thialf and floatovers,” Klaver says. “We have done floatover projects close to 50,000-tonne, as on the Arkutun Dagi platform at Sakhalin. This vessel bridges the gap between the two. We are also exploring if we can do combined lifts with the new crane vessel and Thialf, to even further bridge the gap between heavy lift and floatover.”

The NSCV will also be part of the firm’s fleet renewal. It has already, for example, brought in the deepwater construction vessel Aegir, launched in 2013, and new tugs, as well as other equipment, like barges and hammers. Klaver says the NSCV will likely replace Hermod, sister vessel to the Balder, both of which were built in 1978, and are named after Norse gods, although a date to retire Hermod has yet to be determined, as this will depend on market conditions.

Spec

Heerema’s Thialf performing decommissioning work.

The vessel is being built by Jurong Shipyard, Singapore, and the vessel’s two, new design 10,000-tonne cranes are being built by Huisman in The Netherlands and China.

Basic design on the vessel has completed with Swedish firm GVA and detailed engineering is progressing with Jurong, with construction starting this year and delivery planned for late 2018.

The vessel will be 220-long and 102m-broad, with accommodation for 400 – a large reduction from Thialf’s 750 – which has been set aside to optimize deck space, and transit speed is designed to be 10 knots, compared to Thialf’s 7-8 knots, to shorten mobilization time to the likes of US Gulf of Mexico and West Africa.

While Klaver says the design is more about improving a tried and tested design rather than producing a new concept, one of its key features is a departure from the norm. Through Dutch engineering firm Huisman, HMC has developed two, 10,000-tonne capacity tub cranes.

From the outside, they mostly look like traditional tub cranes, with 145m-long booms, but, they have significant differences, says Anne de Groot, project director at Huisman, primarily around the slew system design.

Traditional cranes slew systems (which enable it to rotate around its base) are based on wheels, running on rails around a center king pin, or bogies. The new cranes, however, are based on a 30m-diameter slew bearing. This is made up of rings, which rotate in relation to each other using rollers with a 7cm-diameter.

The slew bearing design has already been used on Subsea 7’s Seven Borealis and HMC’s Aegir. However, a system of this size has not been done before, de Groot says. “Ours doesn’t have a center point,” he says. “The benefit of this is it saves a lot of weight. If we had built this in a traditional way we would have needed 1000-tonne extra steel for each crane.” The slew motion is also more accurate, he says, and requires far less maintenance. The bearings will be machined in segments in Schiedam then shipped to Huisman’s facility in China to be built into the cranes.

Huisman has also designed the crane house so that it is load bearing, which reduces the requirement for larger load transferring beams used in traditional designs. The slew bearing design also means counter weights are not required at the rear, as on traditional cranes, reducing weight further, and freeing up space there to be used to house most of the crane winches.

“These design changes definitely have an impact on the weight of cranes of this type and also on the maintenance requirement,” de Groot says. “It is more accurate, quieter and providing it all works we cannot see a reason someone would want anything else.”

A key enabler in the design of the cranes has been modern computational analysis. “By applying modern analysis we can improve on the more traditional ways of designing these things,” de Groot says. “By using modern computation we can use less steel and make a crane of this capacity.”

Huisman has also been using computational techniques to help meet a 98.5% uptime guarantee, incorporated into its contract with HMC, a measure, relatively new to the industry, which aligns both contractor and operator’s aims. “Part of the project team is devoted to that,” de Groot says. “It is about reliability and maintenance and those aspects are getting more attention than ever before. We are using simulations to simulate a break-down on certain components to see what effect this has on operations and then either choosing a different component or a adding in redundancy.”

Optimization

Heerema’s Hermod semisubmersible crane vessel.

Changes have also been made to the main vessel design. The deck space has been increased to 12,000sq m with 20,000-tonne load capacity, to facilitate placement of multiple modules to be removed or installed at the same time. “Modules can now be lifted on to the deck not necessarily on to barges, so we are less dependent on weather,” Klaver explains. “In addition, the extra space means more materials and equipment can be stored, such as for a pile driving campaign, saving the need to transfer them from barges, onto which piles, or modules, would need to be sea fastened. There’s a huge advantage in having this deck space.”

Enabling the vessel to run on LNG was also a significant. “With the LNG we make a statement,” Klaver says. “It is our contribution to emissions reductions. I think that this is a novelty in this industry and we believe we will start to set a trend in the market.”

Power will come from 12, ultra-low sulfur marine gas oil or LNG fuelled engines giving electrical power for the utilities, including the DP, thrusters, cranes, etc. Total engines capacity will be 86MW.

New generation

“With this new vessel we make not a step change but we provide the market with some new generation heavy lift capability and make a small step in this market,” Klavers modestly says.

“There will be continuous demand for heavy lift in this market,” Klaver says. “These decisions we take for the long term. We are offering a bigger lifting capacity that can lift platforms in one piece.”

But, the market will also need to adapt to the new capacity, he says. “While there will be continued demand for heavy lift, the market will also need to adapt to the capacity provided,” for example, by designing for larger single lifts, instead of multiple smaller module lifts, Klaver says.