Japan’s Oshima Shipbuilding cooperated with DNV GL, on a joint development project (JDP) for a new 65,000dwt open-hatch general cargo carrier concept. The 210m ship will have a 77,000m3 and 65,000 tonnes deadweight capacity, with a 13.1m draught due to its wider breadth.
The 210m vessel will have eight box-shaped cargo holds with full-width hatch openings of both the ‘piggyback’ (six holds) and folding types (two holds).
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Its design will include project cargoes and two longer cargo holds. Four of the vessel’s holds can be fitted with tween decks to allow for segregating different cargoes. Because of the vessel’s wide breadth and the hull’s double sides and bottom it would not need to use the holds to carry water in heavy ballast conditions.
However the most notable feature of the ship will the use of composite materials. The new design extends their use to the tween decks. According to Oshima, while the composite uses similar raw materials to those found in the hatch covers of the ECO-Ship 2020, and load-bearing components, the laminate thicknesses and the solutions for some of the details are very different.
The tween decks for one short cargo hold comprises of two identical panels; each is constructed of a single skin, with the top plate adhesively bonded to the corrugations which are in turn bonded to end plates. Retractable brackets attached to the hold’s transverse bulkheads support the panel ends.
RINA notes:
The overall efficiency savings must, of course, be viewed in the context of the vessel concept’s other innovations. Another is the use of an optimal-size battery pack, which partially substitutes for the auxiliary engines and compensates for fluctuations in power demand.
A feasibility study conducted by DNV GL, showed that the battery pack could provide a 20% saving in crane operation fuel costs, with an estimated payback of six to nine years, while cutting engine running hours by 50%. Overall, the vessel is 55% below the EEDI reference line for cargo ships.
Finally, a study of comparable open-hatched cargo vessels with typical load profiles showed fuel savings of up to 10% in operating an optimised main engine with a PTO/PTI shaft generator, and important drop in maintenance costs.
