VESSEL REVIEW | Qifan 19 – Chinese cable-laying vessel boasts 10,000-tonne capacity

China's Jiangsu Haixin Shipping Heavy Industry has handed over a new cable-laying vessel to Zhejiang Qiming Offshore Electric Power Engineering. The non-self-propelled Qifan 19 (启帆19) will be deployed primarily in support of offshore wind energy projects by installing submarine cables through which wind farms will supply electricity to numerous end users.

Capable of working with various cable types

The all-steel vessel has an LOA of 108.6 metres (356.3 feet), a beam of 37.2 metres (122 feet), a design draught of six metres (20 feet), a depth of 8.6 metres (28 feet), a displacement of 24,000 tonnes, and a cable turntable located amidships and with a capacity of 10,000 tonnes. The cable capacity is the largest of any cable-laying vessel built in China, while a longitudinal cable laying method will help expand the scope of construction operations by 40 per cent. Up to 75 kilometres (47 miles) of three-core 220kV cable, 130 kilometres (81 miles) of single-core 300kV cable or 2,000 kilometres (1,200 miles) of fibre optic cable can be transported via the turntable.

Onboard diesel generators produce electrical power that is then converted into DC energy, thus increasing the generators' efficiency by 25 per cent while reducing the vessel's operating emissions by as much 20 per cent. This also enables the vessel to stay at offshore work sites for a maximum of 60 days.

Innovative cable installation technology

A water spray cable burial plough can discharge a high-pressure water flow that can carve out a 4.5-metre (15-foot) deep gully on the seabed. Any cables placed and buried in the gully will be better protected from anchor damage, as the excavation depth is at least 1.5 metres (4.9 feet) greater than what is possible with a traditional plough setup.

The vessel has a DP3 system that enables it to withstand Beaufort Force nine and Sea State four conditions. The DP3 system operates in conjunction with four 1,900kW azimuthing thrusters, which can also be used when the vessel is being towed over short distances or when it is being positioned and repositioned in shallow waters.

The vessel eliminates the need for a separate cage for laying cables in the water. As typical cages are more susceptible to wear when often used at depths greater than 40 metres or when carrying heavier cables, these needed to be regularly replaced. The vessel is fully equipped to lay cables at required depths with an accuracy of 0.5 metres (1.6 feet).

The deck equipment includes a towing winch at the bow, a gantry, and an auxiliary crane with a lifting capacity of 50 tonnes. The crane will primarily be used for lifting of any buried cables for maintenance or replacement. Accommodations are for 60 personnel and provisions are available for the installation of a helicopter deck at a later time.

Qifan 19 was designed by the China Shipbuilding Group's 708 Research Institute. Design work was undertaken in compliance with China Classification Society rules including those covering unlimited navigation areas. In addition to connecting offshore wind farms to shore, the vessel can also install submarine cables to distribute electrical power between inhabited islands.