4 minute read
Dredgers of the future
Van Oord’s Vox Amalia and Vox Alexia.
Marine trafc has a serious environmental impact, and dredging vessels are no exception. To minimise the potential negative impact, Van Oord focusses on energy efciency while upgrading existing equipment and designing completely new vessels, such as the Vox Amalia and Vox Alexia. By adding more value to the Van Oord feet, even greater ambitions – related to sustainability – are being realised.
ALL IMAGES COURTESY OF VAN OORD.
Vox Alexia is one of the three LNG trailing suction hopper dredgers that are currently being built at Keppel Offshore & Marine’s shipyard in Singapore.
Sustainable feet investments
Van Oord continues to invest in the feet of the future. Three medium-sized trailing suction hopper dredgers will be added to their feet in the upcoming years. Vox Ariane, Vox Apolonia, and Vox Alexia are currently under construction in Singapore. These LNG hoppers will replace existing vessels and ft in with Van Oord’s aim of making its feet state-ofthe-art and more energy efcient. The vessels will each be equipped with a suction pipe with submerged e-driven dredge pump, two shore discharge dredge pumps, fve bottom doors, and a total installed power of 14,500kW. They will have accommodation for 22 persons. The vessels will obtain a Green Passport and Clean Ship Notation. The new vessels will strengthen the midclass section of their hopper feet. This new generation of trailing suction hopper
dredgers is characterised by a high deadweight tonnage in combination with a shallow draft, which makes them very competitive in various markets, including the market for coastal protection projects.
The new LNG trailing suction hopper dredgers have a signifcantly lower carbon footprint than conventional trailing suction hopper dredgers. Nitrogen oxides and particulate emissions are also minimal with this new generation of hopper dredgers. By 2023, Van Oord will have a dredging feet with three new LNG hopper dredgers to boost the dredging market.
The Vox Ariane will become operational in June 2022. The Vox Apolonia will follow six months later, and the Vox Alexia a further six months later. These three new dual-fuel trailing suction hopper dredgers have cleaner emissions and a signifcantly lower carbon footprint than conventional trailing suction hopper >>
In April of this year, Van Oord’s new trailing suction hopper dredger Vox Alexia was launched in Singapore.
dredgers and so will boost Van Oord’s position in the middle segment of the dredging market.
Vox Alexia
In April of this year, Van Oord’s new trailing suction hopper dredger Vox Alexia was launched in Singapore. Vox Alexia is one of the three LNG trailing suction hopper dredgers that are currently being built at Keppel Ofshore & Marine’s shipyard in Singapore. The vessel will boost the mid-class section of Van Oord’s feet of trailing suction hopper dredgers. This state-of-the-art vessel is ftted with an LNG installation and is a fne example of Van Oord’s sustainability ambition. Jolanda Poots-Bijl, CFO of Van Oord, had the honour of performing the launching ceremony.
i.vanoord.com
Technical specifcations
Name Type Owner Built by Year Total installed power Hopper capacity Length o.a. Breadth Draught Speed Suction pipes Dredging depth Vox Alexia Trailing suction hopper dredger Van Oord LaNaval Construcciones Navales del Norte, Sestao 2017 23,770kW 18.868m3
158,9m3
36,0m 10,3m 15,0kn 2 x 1.000mm 61,0m
How does it work?
From the side of the ship one or two suction pipes descend to the bottom of the seabed.
A trailing suction hopper dredger is selfloading/unloading and sometimes equipped with a pressurized discharging system. It has large, powerful pumps and engines that enable it to dredge sand, clay, sludge, and even gravel from sea or riverbeds. The vessel stores the dredged material in its own hopper and discharges the leftover water overboard.
A trailing suction hopper dredger is equipped with the following equipment: • One or more, rearward extending suction pipes • One or more, dredging pumps to create an under pressure in order to
suck the substance into the hopper • Transportation tubes to transport the substance from the pipes to the hopper • An overfow to discharge the redundant water overboard • Degassing installation to extract any possible gas from the substance in order to reduce damage and increase fuency
From the side of the ship one or two suction pipes descend to the bottom of the seabed. On the end of the pipe a socalled trailing drag head is connected. This head is comparable to a large vacuum cleaner and is trailed along the seabed. In the head there are nozzles connected to a high-pressure water installation that are capable of loosening the material on the seabed. Due to lower pressure in the pipe, the material will be sucked inward and discharged in the hopper.
The hopper can be emptied in a variety of ways, including by: Dumping – This is done by simply opening the doors that close the hopper. Once opened the substance will simply drop to the seabed because of gravity. The hopper will never be completely empty because there will always be some residue and water left inside.
Pressing – High-pressure pumps will pump water inside the hopper to loosen or even liquefy the substance, which can then be pumped via long hoses over great distances (f.i. ashore)
Rainbowing – This is the same principle as pressing, but instead of transporting the substance it will simply be blown away. This is often used to create land.
Crane – It is always possible to discharge the load with a crane, but this will be a time-consuming process.
