The Italeni grab hopper dredger
Transnet National Ports Authority (TNPA) Dredging Services has officially launched its new R1-billion dredger, the Italeni, in Durban.
It is one of three dredgers in the TNPA’s R2-billion programme to renew its dredging fleet, which handles about four-million cubic metres of dredged material a year at South Africa’s ports.
The Italeni is a 750 m³ grab hopper dredger (GHD) and will maintain confined and shallow areas such as berths at South African ports. It replaces the 450 m³ Crane GHD.
South Africa’s ports are dredged to remove silt deposited by rivers that compromise port depth, to remove high and low spots resulting from propulsion wash during the movement of ships and to counter the effect of littoral drift or long-shore movement of sand.
This occurs primarily on the East Coast of the country where the prevailing winds and currents cause a northward movement of sand.
To counter this and to mimic the natural movement of sand, TNPA Dredging Services creates sand traps.
In Durban, these are just below the southern breakwater and extend into the entrance channel. The material dredged from these traps is pumped back onto the northern side of the harbour entrance to nourish beaches and prevent erosion.
The Italeni, which took 16 months to build, has been fitted with the latest technology to improve productivity. The dredger will operate 24 hours a day compared with the 12-hour operation carried out by the Crane.
In addition, the hopper volume is 60% greater.
High-tech advancements include a fully unmanned machinery space, a fully integrated dredging control system, as well as a programmable logic controller engine control system, alarm monitoring system and real-time digital tank soundings.
It also features a customised grab position monitoring system with an accuracy of 2 cm, which is much higher than that of the old craft.
TNPA’s dredger renewal programme began in 2010 with the delivery of the 4 200 m3 Isandlwana – a trailing suction hopper dredger (TSHD).
The Isandlwana and the Italeni were designed and built by Dutch ship builder IHC Merwede.
A contract for a third dredger, a 5 500 m³ TSHD, was awarded to the same company earlier this year.
Transnet CEO Tau Morwe said the budget allocation for the three dredgers represented the largest single capital purchase by TNPA.
All three dredgers are designed to minimise maintenance costs.
Because these new dredgers are fitted with the latest technology, an intensive training programme that includes simulation training for the crew, is built into the contract to ensure that operators understand the high-tech equipment and can properly manage the new vessels.
Morwe said the Italeni would assist TNPA in meeting its objective of providing capacity ahead of demand and would enable it to provide a service to ports in neighbouring countries.
He added that this was in line with the authority’s Africa strategy and would save South Africa’s neighbours considerable sums as the mobilisation cost for sailing a European dredger to a Southern African port was between R20-million and R30-millon before any dredging started.
Meanwhile, TNPA is expected to also award a contract for a new plough tug later this year. This will be followed by a contract for a cutter suction dredger in 2016.
Earlier this year, TNPA Dredging Services replaced two hydrographic survey boats.