Atlantic Star, World’s Largest Combination Container

Atlantic Container Line (ACL) runs a weekly service linking North America’s eastern seaboard with northern Europe.  The transatlantic operation caters for containers, project and oversized cargo, heavy equipment, all types of vehicles, block-stowed general cargo and hazardous goods.  ACL is wholly-owned by Italian ro-ro specialist Grimaldi since 2007.  Hudong-Zhonghua has a reputation as one of the highest quality shipyards in China, with complex special-purpose vessels and naval ships figuring in its prolific output.  Hudong-Zhonghua Shipbuilding won the contract for five G4 (Generation 4) newbuilds in 2012 from New Jersey-based ACL closely contended by two other Chinese yards and two South Koreans.  Construction started at the state-owned company’s new yard on Changxing Island, near Shanghai.  By mid-2016, the operator’s G3 con-ros dating from 1984/85 will be replaced.

In all con-ro vessels, containers are stacked above deck and the lighter ro-ro cargo under-deck necessitates a substantial ballast volume to ensure stability in all conditions.  But, the G4 configuration takes ro-ro freight amidships, while the containers are stowed in raised cells fore and aft of the ro-ro section in a partly open-top arrangement.  This results in better utilisation of the hull and optimisation of deadweight for cargo and the need for ballast water is minimised.  The ballast requirement on full sailings with the G4s will be zero. Cargo effectively replaces conventional ballast.  The innovative design approach was the brainchild of International Maritime Advisors (IMA), domiciled in Dragoer, Denmark.

Just 5.4 m longer than the G3’s 32.2 m, G4  (37.6 m) breed offers twice the dedicated container capacity and significantly increased ro-ro intake, with enhanced capability for ‘high and heavy’ freight.  The contribution of the Danish naval architectural firm Knud E.  Hansen (KEH) to adapt IMA’s con-ro concept to ACL’s  requirements is enormous.  KEH delivered the basic design package, machinery plant arrangement, HVAC (heating, ventilation and air conditioning) and electrical and automation design, CFD (computational fluid dynamics) and model test assistance, intact and damage stability and noise and vibration analyses.  It helped in fine-tuning the design, adjusting the angles of deck ramps and eliminating interior columns to increase storage capacity and relocating wiring and valves to a conduit along the keel to ease access and free-up space elsewhere.

• The capacity of the Atlantic Star  is 45,000dwt
• Design draught of 10.25 m, although this rises to 56,700dwt at 11.50m maximum operating draught.
• The ro-ro section comprises seven fixed and four hoistable car decks, constituting a total standing area of 28,900 m2, allowing for about 760 ro-ro units and 1,307 cars.
• A  maximum deck height of 7.4 m, relative to 6.2 m in the existing G3s, plus increased headroom on the car decks.
• A slot capacity of 3,817 teu is offered within the lattice of cell guides in the holds and above deck, embracing a partial open-top layout.  700 teu more than the G3 ships.
• Usage of ro-ro areas for transportation of containers hoists the overall box intake potential to 3,100 teu, but the dedicated container slot capacity is 1,850 teu, half that of the new vessels.
• The bridge and accommodation of the Atlantic Star are centrally-located, surmounting the midships ro-ro block, rather than being positioned aft, as in the G3s.
• The vessel has a transom stern, high-efficiency rudder and single, fixed-pitch propeller direct-driven by a low-speed diesel engine, with the engine room arranged aft.

Weatherdeck cell guides had constituted an important innovation aboard the G3 class more than three decades ago.  This has had a signal bearing on ACL’s outstanding safety and cargo delivery record.  At the time of the signing of the newbuild contract in 2012, the company said that not a single box has been lost overside in the preceding 30 years.  Continuous or raised cell guides also benefit ship turnaround efficiency, simplifying container spotting and dispensing with the need for stacking cones.

The incoming, wider G4 series employs an angled ramp of the same capacity as that of the G3s, although the stern door is narrower but with more headroom.  Under the MacGregor brand, Cargotec has supplied the complete ro-ro cargo access equipment, hatch covers, and cell guides for the latest ships.

Overall stack heights, from the tank top to the uppermost tier on deck, are greater than on the G3s and the new vessels also offer extra flexibility by way of plugs for 200 reefer boxes in bays 22-24 and 28-32 on deck.

The innovative way in which the hull envelope has been optimised for revenue-earning, in conjunction with the increased efficiency offered by the latest marine engineering technologies, means that the G4 type is equivalent to a 6,500 teu containership in terms of earning power and economies of scale, but with far lower operating costs.

Wärtsilä machinery, the eight-cylinder RT-flex68D engine, rated in this application at around 22,000kW, employs electronically-controlled common-rail technology for fuel injection, exhaust valve actuation and starting.  The installation ensures a service speed of 18 knots, with a power margin to enable schedule recovery if beset by the worst of the North Atlantic weather

Following the selection of the exhaust gas cleaning system as retrofit installations in four of Grimaldi’s Finnlines ro-ro ferries, the group nominated Alfa Laval PureSOx single-inlet, hybrid‘scrubbers’ for the G4 newbuilds.

The Atlantic Star class has a powerful outfit of manoeuvring thrusters so as to better ensure self-reliant handling efficiency, safety and turnaround times, and comprising two tunnel thrusters in the bow and one aft, all of 1,750kW output.

As with sisters Atlantic Concert and Atlantic Compass, Atlantic Companion was a product of Kockums, a name synonymous with Malmoe and the erstwhile, dynamic era of Swedish merchant shipbuilding.  The Atlantic Conveyor from Swan Hunter on Tyneside and the Atlantic Cartier from Chantiers du Nord et de la Mediterranee at Dunkirk are also testaments to past bastions of deep sea mercantile vessel construction.

PRINCIPAL PARTICULARS–ATLANTIC STAR

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