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Da Ji's designers do the heavy lifting

The Naval Architect: April 2018DA JI (28000MPV)

The widely-reported slowdown in the project cargo and heavy lift sectors over the last few years has resulted in consolidation, cost-cutting, and a decline in the number of heavy-lift vessel newbuildings. As well as a merger between United Heavy Lift and Thorco Shipping in 2016 to form Thorco Projects, 2017 saw German ship management company Harren & Partner acquire SAL Heavy Lift from K Line, which only purchased the project cargo specialist in 2011.


Nevertheless, a handful of newbuildings are proceeding in the heavy lift sector to satiate the demand for more economically and environmentally efficient project cargo vessels, given that the average age of vessel in the current fleet sits at 15 years. As in the containership and bulk sectors, vessels are growing in size to maximise efficiency, but are also becoming increasingly flexible in order to allow for diversified and therefore more profitable operation.

 

Flexible operation
Da Ji, the first of a series of four general cargo / heavy lift vessels designed by the Shanghai Merchant Ship Design & Research Institute (SDARI) and delivered in January 2017 to COSCO Shipping Ltd., is an example of these current trends in heavy lift ship design. At 179.67m long and 28m wide, and with a (design) deadweight tonnage of 23,772dwt, Da Ji is at the larger end of multipurpose cargo vessels, allowing it to accommodate for both very large, singular cargoes and smaller, more standard cargoes.


It is this flexibility which defines Da Ji, rendering it a general cargo ship with specialist heavy lift capabilities. The diverse cargoes it has already transported include a new Panama canal lock and part of a nuclear power station. Overlength and heavy cargoes that can’t be conveniently or safely loaded onto the exposed deck can be accommodated in the 54m-long no.2 cargo hold, as was the case for eight sets of RTG container cranes.


Da Ji also has a container capacity of 1,035 TEU, allowing the vessel to fulfil the role of a conventional cargo ship in-between one-off projects and maximise revenue for COSCO. The total cargo capacity of the vessel is 35,684m3.

 

Lift capacity
Perhaps the most important equipment on board a heavy lift vessel are its cranes, which enable the safe but efficient loading and discharging of complex project cargoes. Da Ji possesses three TTS NMF cranes on the port side, the front two of which are identical, and a smaller third crane towards the stern. The larger cranes each possess a SWL (safe working load) lifting capacity of up to 350t, enabling tandem lifting of up to 700t, whilst the smaller crane can manage 100t.

Essential to compensate for the weight of the cranes and the imbalances created during lifting is an effective ballast system. Da Ji is fitted with an automated anti-heeling system, which can adjust the corresponding water ballast required to guarantee stability. COSCO’s own BWMS is utilised aboard to ensure ballast water is compliant, with a capacity across two pumps of 500m3/h.

 

Hull and propulsion
Whilst SDARI needed to ensure that Da Ji could be flexible in its operation, an equally important consideration was fuel efficiency, achieved largely by designing an optimal hull form.

 

SDARI performed comprehensive model testing at the China Ship Scientific Research Center, and combined this with their empirical method to develop a hull form that would achieve maximum energy efficiency over the vessel’s broad anticipated range of speeds and draughts. The hull also includes an innovative bow to reduce speed loss in rough seas; Da Ji is noted to be a particularly fast vessel in the heavy lift sector, achieving 15.50kn at design draught.

 

In terms of propulsion, Da Ji is fitted with a Wärtsilä 6RT-Flex50D, running on HFO, MDO and MGO and achieving an output of 7000kW x 95rpm. The designers say that low-sulphur versions of these fuels will be used once the 2020 sulphur cap comes into place. At present, however, the vessel’s EEDI value still satisfies Phase III, aided by inclusions such as a water-lubricated shaft bearing system to avoid oil leakage. Further efficiency measures include Hub Vortex Absorbed Fins (HVAFs) fitted to the fixed-pitch propeller to counteract swirls and break the vortex, reducing losses of energy in the propeller.

 

Out at sea
Da Ji is also outfitted with a range of anti-piracy features to reassure project cargo owners and improve crew safety. The side-rails that would conventionally be installed have been replaced by thick bulwarks capable to shielding against bullets and knife stabs, further acting as a deterrent to boarding. In such an event, however, crew can retire to the citadel in the forward-located wheelhouse, which features specially-made doors and hatches, plus steam nozzles.

 

Da Ji and its sister ships have been cited as a component of China’s ‘Belt and Road’ development strategy, with the vessel currently deployed on the Europe/Mediterranean route. Notably, only one month after its deployment, the vessel was involved in a rescue in the Mediterranean Sea, responding to a distress call from cargo ship Anna. Da Ji managed to save all 10 crew members, after their stricken ship sank.

 

The success of Da Ji is exemplified by the delivery of two sister ships: Da Xiang in July 2017 and Da Gui in November 2017. A fourth sister ship is expected for delivery this year. In its flexibility, the vessel represents a move away from intense specialisation, which is to be expected as profit margins become thinner and diversification more important, particularly in sectors such as heavy lift. However, as long as large-scale infrastructure projects continue to take place – which there can be some confidence about, given the ongoing growth of the developing nations – there looks to be a more hopeful future for heavy lift and project cargo yet.

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