Singapore’s shipbuilding sector has raised its international profile another notch through Keppel Offshore & Marine’s handover of its first dual-fuel dredger.
The 138m diesel-electric Vox Ariane leads a newbuild class of three trailing suction hopper dredgers (TSHD) booked by Rotterdam-headquartered Van Oord. The location of the construction programme is fresh testament to the increased sourcing of such tonnage by Dutch contractors beyond home shores, while making extensive recourse to Dutch dredge technology and equipment.
Van Oord is a major player in the market with around 100 vessels, some 20 of which are TSHDs, or ‘trailers’, in the 1,000-38,000m3 hopper capacity range. The 10,500m3Vox Ariane is the company’s first LNG-fuelled ‘trailer’, and the new series will boost the fleet’s mid-size section, operational flexibility and energy efficiency.
The owner designed the vessels in cooperation with Groningen-based DEKC Maritime. A single suction pipe is deployed from the starboard side, with the scope to draw material from a depth of 42m.
The entire dredge outfit was contracted from Royal IHC, including the 1.1m-diameter suction pipe incorporating a submerged, electrically-driven dredge pump, two shore discharge pumps, and three hopper jet water pumps. Unloading of spoil or reclamation sand is also possible by way of five bottom doors.
The pumps are equipped with the proprietary Curve impeller, distinguished by its particular shape and blade curvature, conceived to marry optimum suction properties with prolonged service lifetime. Robustness, longevity and ease of maintenance are vital factors in the hard business of dredging, in which comprehensive Dutch capabilities stem from the exchange and depth of experience in both operations and engineering.
Vox Ariane has total installed power of 14,500kW, using Tier III-compliant main machinery. The nature of the engineering arrangements overall has met the Bureau Veritas criteria for the Green passport and Clean Ship notations.
The main generators, main and distribution transformers, propulsion drives, associated control systems and transformers were supplied by ABB in a ‘package’ deal. This also encompassed the electrotechnical specialist’s power management, alarm and vessel management systems, as well as customised dredge control system. ABB’s involvement has extended to the complete navigation solution and bridge hardware.
The considerable array of mechanical deck equipment that is the wherewithal of a suction dredger is augmented on Vox Ariane by two 640m3-capacity LNG fuel tanks, mounted in-line above the hopper. The single-shell, polyurethane insulated storage tanks were supplied by Wartsila as a development on its LNGPac system.
The delivery featured a new in-line tank connection space (ILTCS) containing the process gear, mounted forward of the containment units instead of the usual on-top installation. This arrangement benefits line-of-sight from the bridge, and is also claimed to reduce risk of damage.
Expediency in energy usage is demonstrated in the use of waste heat from the engine exhaust gases and cooling water for the accommodation central heating and also in means of recovering ‘cold’ from the heat-induced regasification of the LNG fuel to feed the engine for use in air conditioning and the stores freezer room.
The steering and rudder systems are of Dutch origin, having been supplied by Damen Marine Components. Twin Van der Velden Master rudders, featuring a fishtail profile, are complemented by two Commander piston-type steering systems from the same manufacturer. Class-approved by Bureau Veritas for speeds up to 15 knots, the rudders generate a torque of 270kNm and bestow high manoeuvrability, particularly so in shallow waters, with rudder angles of up to 65deg.
Vox Ariane is to be followed out of the Keppel complex by Vox Apolonia, floated out last September, and the recently launched Vox Alexia.
