‘Wild Dragon’ concept launched at Kinderdijk
Chang Jiang Kou 01 enters the water at Kinderdijk on Saturday.
The naming and launch ceremony for the 12,000m³ trailing suction hopper dredger Chang Jiang Kou 01 has taken place at the IHC Merwede shipyard at Kinderdijk in the Netherlands.
IHC Merwede is building the vessel for Yangtze Estuary Waterway Administration Bureau MOT, which is based in the People’s Republic of China. The ceremony was performed by Mrs Tian Liying, spouse of His Excellency Mr Zhang Jun, Ambassador of the People’s Republic of China in the Netherlands.
The contract for the design, construction and delivery of two 12,000m³ trailing suction hopper dredgers (Chang Jiang Kou 01 and Chang Jiang Kou 02) was signed between Yangtze Estuary Waterway Administration Bureau MOT and IHC Dredgers in July 2008. The keel for the first dredger, Chang Jiang Kou 01, was laid on 21 December 2010 and the vessel will be delivered in the second quarter of 2012.
The two ships are named after the mouth of the Yangtze River, where they will carry out maintenance dredging jobs over a distance of 122km. The Yangtze River leads to the Port of Shanghai and represents half of its total capacity. Shanghai is the world’s busiest container port and is still growing rapidly in terms of its overall size and throughput.
The ships have been specifically designed with the high current velocity and soil properties of the Yangtze River in mind. As a result, the vessels will be equipped with the patented IHC Merwede Wild Dragon draghead.
The vessel owner must deal with extraordinary compacted clayish fine sand banks in the Yangtze estuary that previuously could only be dredged with cutter suction dredgers. However, the crowded traffic in the estuary practically prohibited the use of stationary dredgers. A first attempt to do the job with a TSHD revealed that the suction head bounced off the soil and was reduced to merely ‘pumping turbid water’.
This led to experts from IHC Parts & Services, IHC Dredgers and MTI Holland collaborating with the owner’s experts. In a creative and iterative process, accompanied by extensive scale tests, a succession of draghead concepts was developed.
The outcome was a unique and patented draghead, the Wild Dragon, equipped with two rows of resistant teeth, supplied with high pressure jetwater going through the teeth. The jetwater causes dilatation of the sand around the teeth’s surface, loosening the cohesion of the sand and simultaneously flushing the teeth, decreasing penetration resistance and subsequent draghead forces. Test results were even better than expected.
The Wild Dragon bites deeper and causes less resistance than other trailing head designs, not only in densely packed sand but also in softer soil types. Consequently, production increases at lower fuel consumption, emissions and cost. The entire process runs more smoothly and component wear is slowed. Due to the increased mixture density, the settling in the hopper is quicker, overflow loss and turbidity is reduced.
The 132m LOA Chang Jiang Kou 01 has a beam of 27.3m and a draught of only 8.37m. The 12,000 m3 capacity vessel will dredge to depths of 25m through two 1,000mm diameter suction pipes.
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