Mooring service addresses shortage of subsea crane vessels

Kongsberg Maritime has devised a mooring service said to expand the capabilities of offshore construction vessels (OSCVs).

It involves integrating a purpose-designed anchor-handling winch, shark jaws and stern rollers into the design of newbuild vessels, allowing them to take on more tasks independently.

The service, which the company claims could address the lack of vessels capable of large-scale mooring installations, is said to enable OSCVs to undertake a wider range of mooring operations, extending the operational window and limiting the requirement to bring in further vessels at the field.

Adding winches and stern rollers can lead to more efficient over-stern deployment of mooring lines, Kongsberg added. This is a technique commonly deployed from anchorhandler tug support vessels.

The winch can be permanently installed or portable, loaded on board only when required. The shark jaws and stern rollers would be permanently fitted to the vessel.

A subsea crane, common to many OSCVs, can lift and install suction piles, and it can hold the load of mooring chain. Kongsberg’s winch package includes one drum for work wire and two cable lifters for handling chain.

At present, OSCVs are limited to setting large suction piles or driven piles into the seabed using onboard cranes and ROVs. The company claims its service would allow the vessels to perform these tasks more safely and efficiently.

Runar Hjele, Kongsberg Maritime's sales director of Offshore Construction & Support, said over the years ahead, there will be a shortage of vessels with subsea crane and the deck area to support the anticipated high volume of large anchors and mooring lines.

Hjele added, “With the new space-saving Kongsberg Maritime system, OSCVs are prepared for the installation of anchors and pre-lay of mooring lines (both chain and fiber rope) without compromising on their construction capabilities.”