DEME Takes Delivery of a New 11,650 m3 TSHD from IHC Merwede

The latest delivery from IHC Merwede is the Breughel. The trailing suction hopper dredger (TSHD) was handed over to her owners DEME on 21 October 2011. The design is an evolution of the successful series including the Brabo and Breydel, which were delivered in 2007 and 2008. Nevertheless, the Breughel received significant upgrades for regulatory compliance and optimised efficiency.

Shallow water

Characteristic for the design of the Breughel is herlargebeam,whichgivesheralotofhopper capacity combined with a small draught. This allows for operations in shallow water, where usually only smaller, less efficient vessels could work. Production efficiency is optimised by using the one-man-on-bridge concept. With the navigation and dredging controlled by a single person, miscommunication between captain and dredge master is ruled out. On Breughel, the bridge console has received further upgrades when comparing with her sister vessels. The console has four screens, which are all touch screens and can be interchanged at will, a typical feature for an integrated bridge. The nautical equipment was supplied by SAM Electronics and the dredging automation came from IHC Systems.

Cofferdam

Another significant change is related to new constructional requirements regarding fuel tanks in the sides. To avoid oil spills in the case of minor hull damage, wing tanks now have to be separated from the side shell by a cofferdam. On Breughel, this cofferdam is about 850 millimetres wide. To keep the vessel’s range intact, the total fuel capacity was kept unchanged by extending the fuel tanks further forward.

Four gearboxes, six outputs

Shipowner DEME favours the efficiency and simplicity of direct shaft-driven propellers and dredge pumps over a diesel-electric installation. As the engine speed is governed by the required rotation speed for the pumps, both propellers are of the controllable pitch type, to ensure manoeuvrability. A different engine is installed on port and starboard, as the pumps connected to them have different characteristics. The portside main engine has a front PTO to drive the dredge pump through a three-speed gearbox. The three different reduction ratios allow matching of the pump speed with the characteristics of the spoil, all the while remaining in a suitable rpm range for the portside main engine. This is a Wärtsilä 12V32 engine producing 6,000 kW. The starboard main engine drives two jet pumps through a custom- built Jahnel single input-dual output gearbox connected to the front PTO and also a shaft generator through a PTO on the aft gearbox. This engine is a Wärtsilä 8L32 rated at 4,000 kW. Both main engines are IMO Tier II compliant regarding their emissions. They are equipped with the unified controls (UNIC) embedded engine management system, which ensures an extended lifetime. The UNIC system includes among others engine safety monitoring, fuel injection and timing control, knock detection, start/stop sequencing and system diagnostics. The four gearboxes are automatically controlled with electric/pneumatic controls by the ship’s automation system. The propellers are positioned in fixed nozzles with flap-type rudders behind. Each rudder can rotate over 90 degrees for maximum manoeuvrability, a prerequisite for port maintenance dredging.

Economiser

The Breughel runs on heavy fuel for economic operation. The thermal oil for the heating of the HFO bunker tanks is heated in an exhaust gas economiser, or – in port – in an MDO-fired thermal oil heater. The electrical installation was done by Imtech and features a 60 Hz 400 Volt main power supply, two bowthrusters are electrically driven. Their speed is controlled with a resistor load bank, which is located in the bowthruster room.

Hopper

Breughel’s standard suction pipe allows for dredging to a depth of 28 metres. By using an extension piece, which is stowed on deck, the suction pipe can be lengthened to allow dredging up to a depth of 43 metres. The hopper is equipped with bottom doors for quick discharging of the spoil. When this is done in very shallow water, it may not be possible to open the bottom doors. For this reason, there are four pre-dumping doors installed in the centre box keelson. When enough spoil is discharged through these doors and the Breughel floats higher in the water, all ten large bottom doors can be opened for a speedy discharge. The dredge pump can also be used to discharge the hopper through the deck line, leading either to a pipeline or to the rainbowing nozzle on the bow. The jetwater system is used to liquefy the spoil in the hopper. The gate valves on deck and the watertight seal of the dredge pump are continuously flushed with clean seawater to prevent clogging with sand. To ensure a long lifetime, this seawater piping is made of corrosion-resistant composite material (GRP).

No other salt-water piping enters the engine room, as cooling of the main engines and genset is with box coolers. The bottom doors, pre-dumping doors and the valves in the pressure piping are actuated with hydraulic cylinders. These are powered by hydraulics, through a hydraulic ring line which runs around the hopper. The hydraulic system was engineered and supplied by IHC Hytop.

Double-walled pump

IHC Parts and Services supplied the dredge pump, which features a double-walled construction. The inner wall is of hard-wearing material and protects the outer, structural housing of the extremely abrasive spoil. An added benefit is the extra layer of protection in case explosives are dredged from the bottom. A degassing installation is provided to remove biogas from the spoil before it enters the dredge pump.

Deck gear

The deck cranes include a 36 ton SWL crane aft, which can lift the dredge head, and a ten ton SWL crane forward for general purposes. A large deck work shop has direct access to the aft deck and is used for the maintenance of the dredging equipment. A stern anchor is lodged in the ship’s stern. This is used in land reclamation projects, when the dredger is beached to discharge through the rainbowing nozzle. To avoid using the propellers in shallow water, the Breughel can pull herself back to deeper water by hauling the stern anchor.

Safety

CCTV cameras are installed in strategic locations to give the captain a view of the dredge head and other positions which may not be in the direct line of sight from the wheelhouse. The visibility from the wheelhouse is excellent however, with full-height windows facing the hopper. The lifeboats can be launched by davits on either side. The engine room is protected with a gas-fire extinguishing system, with a low- pressure watermist system for local protection of high-risk areas.

Financing

The Breughel was ordered in May 2010. She was constructed on the covered slipway in Krimpen aan den IJssel, and completed at the quay nearby after launching. She showed her prowess during seatrials lasting four days. Many shipbuilders have complained that difficult financing is putting the brakes on shipowners, which would otherwise commission new ships. In June 2011, the IHC Merwede Group has secured a 50% increase in financing to a total of €1.5 billion, allowing the shipyard to provide shipowners with financing during the construction of a ship. In typical DEME tradition, the Breughel was named after a historic Flemish figure. Pieter Breughel the Elder was a Flemish renaissance painter of the 16th century. He was nicknamed Breughel the Paisant for his alleged practice of dressing up like a peasant to blend in at local weddings and other celebrations for inspiration for his paintings.

Bruno Bouckaert