We take a closer look at what is perhaps the most crucial piece of onboard machinery in offshore wind installation.

THE MOST IMPORTANT TOOL IN THE BOX

For an offshore wind installation vessel, a main crane is like a carpenter’s hammer: the most important tool in the toolbox. There, however, is where the comparison stops, because SEA CHALLENGER’s main crane is one of the most up-to-date cranes in offshore wind, capable of feats far in excess of anything you can do with a hammer.

Wrapped securely around one of SEA CHALLENGER’s immense jack-up legs is nothing less than a GustoMSC GLC-900-ED-S electricity-driven bogie crane. Located on top of the jack-house, this powerful crane revolves an unrestricted 360° around the portside aft jack-up leg of the vessel.

With the extended boom, this amazing machine can create a 121-metre hook height above the deck. And it’s capable of lifting the equivalent of not one, but two Airbus 380s – the world’s largest passenger aircraft – at a distance of up to 24 metres from the crane’s pedestal. Granted, no one has actually tried that trick as yet, but the basic specifications of this impressive machine tell the clear story that such a feat is definitely possible.

It’s a comparable crane to that of SEA INSTALLER, but with the addition of a boom insert that enables greater lifting heights. With the standard boom, the vessel can lift a 900-ton foundation into place – a comparatively short but heavy lift. Towers and nacelles require the boom to be extended, sacrificing a little lifting capacity at a maximum of 700 tonnes.

NEW TYPE OF CRANE

The GustoMSC GLC-900-ED-S, as with other cranes fitted around a jack-up leg, has a significant advantage compared with common pedestal cranes, as there is one jack-up leg less in the way during lifting operations and more deck space is made available. Placing the main crane around a jack-up leg and directly on the jacking house is a smart move for installation vessels, which need to handle increasingly larger and heavier foundations, towers and nacelles.

It’s still early days for the new around-the-leg cranes. In fact, the cranes for SEA INSTALLER and SEA CHALLENGER were among the first such designs to be constructed anywhere in the world.

BUILT BY THE BEST

Netherlands-based GustoMSC is a leading design and engineering company that works with the offshore exploration, construction and production industries, providing solutions centred on all types of jack-up units, semisubmersibles or mono-hull vessels. The company designs all types of mobile units, vessels and associated equipment, mainly producing jacking, fixation and skidding systems, and offshore cranes.
SEA CHALLENGER’s main crane isn’t the only major system supplied by GustoMSC.

The vessel is also equipped with a GustoMSC 9000C continuous hydraulic positive engagement jacking system. This state-of-the-art system, which is lighter and more compact than earlier systems, provides full continuous motion jacking up, making jacking operations easier, faster and safer, especially where frequent repositioning is required.

WHERE TO NEXT WITH OFFSHORE WIND CRANES?

What will larger and heavier components mean for new directions in offshore wind crane design in the future? According to GustoMSC project manager Arjo van Putten, the increased weight of the foundations, at least, doesn’t necessarily mean that much.

“There are offshore cranes able to lift as much as 5,000 tonnes, but they have high day rates compared with vessels like SEA CHALLENGER, and for the installation of the turbines a jack-up platform is preferred,” he explains. “Of course, as the size of the turbines increases, the lifting height of the installation cranes needs to increase too, but lifting capacity where the turbines are concerned is not really a problem.”

“That said, the less costly such cranes are to build, the better. But, while materials that are both lighter and stronger than steel are on GustoMSC’s radar, there’s a long way to go before they can be cost-effectively deployed for heavy lifting. Moreover, stronger steel qualities are available than some years ago, helping to keep weight and costs down even as lifting capacity and reach increase. In addition, our company has long had its focus on designing lightweight structures, especially for the boom.”

NORMAL BOOM

· Maximum crane capacity: 900 t @ 24 metres outreach
· Minimum outreach: 14.5 metres
· Hoisting height from main deck – approx. 102 metres

LONG BOOM

· Maximum crane capacity: 700 t @ 28 metres outreach
· Minimum outreach: 20.6 metres
· Hoisting height from main deck – approx. 121 metres

 

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