The 3,500m³ Trailing Suction Hopper Dredger Diogo Cão was launched last Saturday at the Keppel Nantong shipyard in China, a subsidiary of Keppel Offshore & Marine.
This green vessel – the second of three 3,500m³ hoppers to be launched – is equipped with an exhaust gas treatment system filtering out and virtually eliminating many pollutants from the exhaust gases.
In total, Jan De Nul Group ordered six such ultra-low emission Trailing Suction Hopper Dredgers, called Ultra-Low Emission Vessels, five of which are being built at Keppel: three small 3,500m³, two medium-sized 6,000m³ and a larger vessel at 18,000m³.
All six vessels are diesel-electrical powered, with engines allowing optimal use of generated power but with low fuel consumption and emissions. In addition, the vessels are equipped with a two stage highly efficient exhaust gas filter system, resulting in emissions complying with the European Stage V regulations for inland waterway vessels.
Robby De Backer, New Building Director at Jan De Nul Group: “We are delighted to be leading the way in compliance with the most stringent global emission limits with the world’s first EU Stage V dredgers, which will be highly fuel-efficient, reliable, versatile and productive.”
“As the new dredgers will frequently operate in estuaries, rivers and coastal areas near urban areas, we decided to limit the NOx emissions to a level 30% below the actual IMO Tier III requirements, and to reduce other potentially harmful contaminants that are currently not regulated by IMO,” added De Backer.
The Diogo Cão’s design
The design of the Diogo Cão is based on the successfully operating 3,400m³ TSHD Alvar Nuñez Cabeça de Vaca and Sebastiano Caboto, built in 2011. The vessels combine a shallow draught with high manoeuvrability, making them very suitable for working in confined areas.
The Diogo Cão is in diesel-electric execution: all major drives (thrusters, dredge pump, jet pumps…) are electrically driven, and controlled by means of frequency converters. In this way each system can operate at its optimal speed and power.
Power is generated by means of three diesel generator sets. A control system automatically starts and stops the sets depending on the power requirement. Asymmetric load sharing results in optimal load distribution over the diesel generator sets.
Hopper capacity 3,500 m³
Deadweight 5,500 t
Length o.a. 89.3 m
Breadth 22.0 m
Max. dredging depth 27.6 m
Suction pipe diameter 800 mm
Speed 11.3 kn
Pump power (trailing) 1,250 kW
Pump power (discharging) 3,000 kW
Propulsion power 2 x 1,100 kW
Total installed diesel power 5,510 kW
Accommodation 16 persons
Jan De Nul Group also announced that with the Diogo Cão now being launched, the keel laying of the first 6,000m³ dredger is planned to take place on 19 July at the Keppel Singmarine in Singapore.
The company has decided to name both 6,000 m³ Trailing Suction Hopper Dredgers after two decommissioned vessels of the Groups fleet: Sanderus and Ortelius.