Flexible new breed raises handysize bar
The 38,762dwt geared handysize carrier ‘True Love’ has provided the Green Dolphin concept with its seagoing debut - leading a robust and exceptionally economical new generation of versatile ‘workhorses’ for multifarious bulk cargo commerce. David Tinsley reports.
Developed by Shanghai Merchant Ship Design & Research Institute (SDARI), and with early technical input from DNV GL and Wärtsilä, the Green Dolphin 38 class is testament to the level of operating performance and transport efficiency available at competitive cost through Chinese design and construction. Commercial vindication of the GD38 technical project by owners and charterers worldwide has been such that over 100 firm orders and options have been placed to date, involving at least 13 different Chinese yards.
Although essentially intended for serial output, with the attendant production and buyer cost benefits, the GD38 concept offers various possibilities for tailoring to individual operating needs plus a number of ’future-proofing’ options such as scrubbers, catalytic reduction systems and dual-fuel machinery. One example of customisation expressed in the True Love is the ship’s IC ice-class standard. The vessel’s trading reach has thereby been enhanced through the capability to navigate in light ice conditions, and with the assistance of icebreakers when necessary.
Handed over in May by Chengxi Shipyard, she also has the distinction of being the first vessel delivered to CSSC Shipping (Hong Kong) since the latter’s establishment as the ship leasing arm of the China State Shipbuilding Corporation (CSSC).
True Love and the subsequently completed sister Dolce Vita from the Chengxi yard have joined the growing fleet controlled by freight contractor Aquavita International. Working out of offices in Greece, Monaco, the Ukraine and China, Aquavita is acting as exclusive commercial manager for the two ships. The company has around 60 modern bulkers under its commercial aegis, and lifted over 16m tonnes of dry bulk commodities last year on behalf of both producer and end-user clients.
Aquavita’s chief executive officer Evgeniy Lavrenko identified low consumption, extended cubic capacity, wide hatch openings and the 1C ice class as key attractions of the design encapsulated by the two new fleet additions.
Flying the Marshall Islands’ flag with Majuro as port of registry, True Love is under the ownership of Cha First Shipping and technical husbandry of Olive Shipmanagement.
One of the fundamental strengths of the GD38 concept is that the design has been developed after close consultation with the user community, namely the operators and charterers immersed in the handysize bulker sector, and from discussions with shipbuilders. Feedback pointed to fuel consumption, trading flexibility, maintenance costs, environmental compatibility, use of proven technology and environmental compatibility as the most pressing considerations.
Advances in energy efficiency and trading performance are pertinent not only to the economic requirements of owners and charterers, and for compliance with Energy Efficiency Design Index (EEDI) regulations, but are also fundamentally important to shipyards’ efforts in promoting designs that can confer a competitive shipbuilding edge in an oversubscribed market.
EEDI calculations for the concept design had shown a value of 4.7g of CO2 per tonne-nautical mile, 25% below the bulker reference line.
The hull lines have been optimised not to a specific speed and condition, but to a representative operating profile embracing differing draughts and speeds, with emphasis on the 10-14 knot range. The full form in the standard version results in an absence of bow rake, and is bulb-less in the interests of improved overall performance.
Operational flexibility in a modern-day tramper is as crucial to efficiency as is competitive fuel consumption per freight tonne. The long-term trading versatility and value incorporated in the GD38 is expressed in various ways, including dimensioning to allow operation to the widest range of ports and terminals catering to handysize bulk traffic, maximisation of cargo cubic, deadweight and scope within the hull envelope, and equipping with deck cranes to ensure cargo working self-reliance and speed.
Designed and built in accordance with IACS Common Structural Rules, the GD38 is laid out with five holds accessed through exceptionally wide hatchways served by folding covers, and plumbed by four fully electric deck cranes mounted on high stools along the centreline. The hatches to Nos 2,3, 4 and 5 holds span 27m of the vessel’s 32m breadth, and are flanked by continuous, rather than individual, coamings.
Total underdeck revenue-earning volume is some 50,500m3 on a grain-equivalent basis. Holds 2, 3 and 4 each have a similar intake of around 11,000m3, the aftermost No5 offers 9,400m3, and the narrower No1 hold provides 8,100m3.
One of the most significant aspects of the cargo section design is the elimination of overhangs in three of the holds. By dispensing with top wing tanks and bottom hopper tanks in holds 2,3 and 4, the resulting ‘open-hatch’, box-sided configuration is conducive to ease of stowage of products such as steel coils and forestry goods, and also project cargoes.
The underdeck spaces are conducive to the gamut of main bulk commodities, including ore, grain, coal, fertilisers, seedcake, sulphur, timber products, and also dangerous solid bulks and cement, and tank top load capacity is such as to allow for two tiers of 20t steel coils. Additional payload opportunities are provided by the ability to carry timber on the hatchcovers. The covers have integral grain feeder and cement loading openings.
Each of the four cranes is rated for a 30t safe working load at 26m outreach. Electric, variable frequency drive cargo cranes have been adopted in the interests of operating efficiency and expeditious turnaround times. The absence of hydraulics also promotes cleanliness and reduces the risks of pollution and cargo contamination through hydraulic oil leakage.
The cargo holds are equipped with compressed air, power and wash water supply at tank top level for portable cleaning systems. The required cleaning water and resultant wash water are held in designated tanks. Through the adequate provision of water ballast capacity in the double sides and double bottom, a heavy ballast condition is achievable without using the midship cargo hold to carry ballast water.
Wärtsilä two-stroke propulsion machinery has been specified for the lead GD38, in the shape of a five-cylinder model of the RT-flex50D design. Employing an electronically-controlled common-rail fuel injection system, the slow-speed, reversible diesel provides direct drive to a SDARI fixed pitch propeller.
The contracted maximum continuous output of 6,100kW at 99rpm denotes the specification of the engine in its R4 rating, leading to a parsimonious continuous service rating of 4,575kW at 89.9rpm and resulting low fuel consumption. The moderate level of operating output selected for the new class of bulker may be set against the engine’s nominal MCR of 8,725kW at 124rpm.
When the ship is entering a SOx Emission Control Area, a switch can be from heavy fuel oil (HFO) to ultra low-sulphur distillate, with the requisite maximum sulphur content of 0.1%. Two self-cleaning purifiers are installed to treat the HFO, whereby one is always on standby, and with one of the two also handling the MDO purification task.
At the time of writing, the Wärtsilä marque had been nominated for 31 other, firmly booked Green Dolphin handysize carriers, while 50 of the ships are to be installed with competing MAN engines. The popular choice in the MAN stakes is the S50ME-B9 in its five-cylinder format, at a specified MCR of 6,100kW at 99rpm.
Unlike the preponderance of GD38 bulkers on order, True Love and Dolce Vita have not been specified with aft-end energy saving appendages, neither has a follow-on series of six from Chengxi Shipyard for Cosco Bulk.
In contrast, and so as to achieve a higher propulsion efficiency, otherwise common features of the GD38 programme are a wake equalising duct in front of the large diameter, slow-rotating propeller, and Hub Vortex Absorbed Fins (HVAF). The latter device is designed to reduce energy losses associated with hub vortices through the fitting of fins to the propeller cap. For the standard GD38 equipped with such appendages, the designers had indicated an expected fuel consumption of approximately 18t per day, making 14 knots at 4,575kW CSR on the design draught, with 15% sea margin. However, it can be appreciated that many variables pertain, including the actual type and grade of fuel and its calorific value.
In the case of the True Love, Aquavita’s Evgeniy Lavrenko advised Motorship that experience with the ship so far had shown a main engine consumption of 20.3 tonnes per day of HFO, running at a full speed of 14.2 knots in laden condition and good weather. In addition, consumption by the auxiliaries has been 2 tonnes/day, plus 0.8 tonnes/day by the boiler. As far as the company can tell, the figures appear to be either better or similar to leading, competing designs in the handysize sector.
The auxiliary installation in True Love comprises three gensets driven by Daihatsu 5DK-20e diesels, supplied by the Japanese company’s Moriyama division. Steam is raised by a Saacke composite boiler.
By mid-May this year, the GD38 type had logged firm orders for 84 vessels, plus 19 options, all in China. Among the largest batches are 24 ships for Marine Capital Corporation, 14 for Pioneer Maritime and seven for Peter Doehle. DNV GL is responsible for classing 32 of the ships definitely booked, with Lloyd’s Register accounting for 33, and CCS, BV and ClassNK involved with the other newbuilds.
The concept has been developed further in the Green Dolphin 575 single-skin, handy size bulker, and the Green Dolphin 84S shallow-draught, post-Panamax type.
PRINCIPAL PARTICULARS - 'TRUE LOVE' Length overall 179.95m Length b.p. 177.00m Breadth, moulded 32.00m Depth 15.00m Draught, scantling 10.50m Deadweight, maximum 38,762t Gross tonnage 25,515t Main engine Wartsila 5RT-flex50D Speed 13.8 knots Class DNV GL Class notations 1A1, ICE-1C, Bulk Carrier, ESP, CSR, BC-A, DG-B, E0, CLEAN
Recyclable, BWM-T, GRAB[20t], COAT-PSPC(B), BIS, Holds(2,4) may be
empty, TMON Flag Marshall Islands
PRINCIPAL PARTICULARS - 'TRUE LOVE'
1A1, ICE-1C, Bulk Carrier, ESP, CSR, BC-A, DG-B, E0, CLEAN Recyclable, BWM-T, GRAB[20t], COAT-PSPC(B), BIS, Holds(2,4) may be empty, TMON
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