Khaleej Bay, a heavy-duty dredger

The Khaleej Bay was specially designed to withstand the harsh climatologically and geographically conditions in the Middle East. “We are extremely proud that ADSB is the first company in the Gulf to build a world-class dredger of this size, complexity and capability”, said ADSB?s ceo Lawrence Holliday. It is the first new dredger for this local dredging company for many years and the first of its size built at a foreign yard by the Damen Group.

With its high-energy cutter, the new dredger can dredge sandy and rock composite seabeds for the maintenance and construction of ports, harbour basins, channels and intake trenches. It can also be deployed for retrieving seabed material.

The type CZ600 dredger was designed by De Groot Nykerk, now Damen Dredging Equipment and part of the Damen Shipyard Group in the Netherlands, under subcontract from ADSB. Classed by BV for coastal service, it has a draught of only 2.20 metres. With cutter power of 920 kW and inboard pump power of 1,800 kW, the vessel can perform dredging in depths of 3 to 18 metres.

Owner?s requirements

The Damen Group undertook the design and construction contract based on the owner?s requirements that the dredger had to be able to work in confined spaces down to a minimum width of 50 metres and to remove a large range of soil gradations from silt up to hard material. In line with the owner?s specifications, Damen supplied an extensive design and construction package including the engineering and supply of its major components such as dredge pump diesels and gearbox, generators, spud carrier, spuds and spud hoisting system, winches and cutter ladder suited for a submerged dredge pump.

Damen appointed VOSTA LMG to design and supply the cutter and spud systems, consisting of the cutter ladder, cutter head, spud carrier and dredging winches, and specified a five and six bladed cutter type SC/40, suitable for sand, clay and soft rock.

The spud carriage has a stroke of 5.5 metres with a 750kN pushing force. It runs on adjustable tracked boogies to reduce concentrated loads on the carriage and the guide rails. The spuds can be tilted without the use of an external crane, which allows it to pass under low bridges.

The cutter ladder has been designed for harsh local conditions and the high spud forces. The cutter drive consists of a Lohman & Stolterfoht gearbox plus two 500 KW water-cooled electric motors.

The dredger is equipped with two 955 kW Caterpillar 3512B SCAC engines to drive the inboard dredge pump. Two main generator sets are installed, each with a 1,500 kVA Caterpillar 3512B SCAC/Stamford configuration. One set can deliver the required power for the cutter drive at a nominal power range of 450 kW and the electric/auxiliary systems.

To keep the electrical and instrumentation power net clean, both power supply systems have been separated and equipped with the appropriate filters and drive systems.

When operating under full cutter power both generator sets will run in parallel, again separating the large power consumers from the electrical and instrumentation network. Spud carriage, anchor boom configuration and spud lifting are the only hydraulic functions on board, which are powered by a separate mounted electric/hydraulic power pack. n