Largest crane vessel, largest cranes

Deeper water is exerting its own particular pull, and so Heerema’s New Semi-submersible Crane Vessel (NSCV) designed by GVA Engineering will be competing for its slice of truly huge marine construction works.

But its deck equipment needs to be of the same scale, so each of the vessel’s two cranes, presently being built by Dutch company Huisman, will be capable of lifting 10,000 tonnes at a radius of 48m.

Fully extended, the crane boom will have a length of 145m and with the boom up, the crane will reach a height of 210m above the waterline. But it’s down at the base that there’s real interest, as unlike traditional tub cranes which make use of either bogies or large wheels to slew the crane round Huisman’s innovation is to use large bearings, an approach that, the company is sure, will represent a ‘step change’ for the industry.

The simple enclosed bearing design allows for very accurate control of the slewing action, and also means less maintenance. More, this system is significant lighter than the traditional approach; a large bonus as despite the extraordinary lifts, all semi-submersibles have to watch their own weight.

These bearings will need a diameter of no less than 30m and Huisman is manufacturing them in-house, an approach that suits the company well as it has built up its ability to deal with large, tailored components by investing in truly huge milling machines and handling equipment.

There will probably be more of these cranes coming from the Huisman facilities: the technique of slewing the crane around on bearings seems to be gaining ground, having been used both on the Seven Borealis’ 5,000 tonne mast crane and the 4,000 tonne crane for Heerema’s Aegir prior to this latest order.

By Stevie Knight