Trans RINA, Vol 153, Part A4, Intl J Maritime Eng, Oct-Dec 2011


10 15 20 25 30 35 40 45 50


0 5


8000 9000 10000 11000 ME total kW Figure 14: Fuel consumption (tonnes per day) against main engine power for modern14 dry bulk carriers6


For handymax ships the market demand for the ship size remains, in particular for grain cargoes. The temptation to seek further commercial advantage through expansion of beam to achieve greater cargo volume should possibly be resisted,


with ship repair capacity limitations


providing a justification for the maintenance of the existing Panamax dimension even though the vessel’s route may permit


larger dimensions. Dry-docking a


65,000 dwt ship in a 300,000 dwt dry-dock is relatively inefficient and will be unattractive to shipyards where the option for larger ship dockings are available. This will have a time and cost


implication for the owner,


narrowing the range of possible repair locations. For ships in the larger Panamax sector the advantages of economy of scale and operation may offset the disadvantages of reduced choice of drydock location and increased drydocking costs, unless the ship will be operationally constrained to the Mediterranean or Baltic Seas, where the supply of docking capacity for larger ships is relatively limited. For drydock designers the existing Panamax constraint for dock design should be regarded as obsolete.


For the existing Panamax class of ships it seems inevitable that dimensions will increase over time to meet


the new constraint development are uncertain. but


the dynamics of this It is unlikely that a single


coherent new class of bulk carrier, such as the existing Panamax class, will emerge, because of the specifics of trades and terminals. Change will also take time, given that there is a significant volume of


“traditional”


Panamax tonnage in process of delivery at the time of writing this paper and the Panamax fleet is relatively young.


will inevitably be pursued through increased beam whilst 14 Built after 2000. A-228 ©2011: The Royal Institution of Naval Architects Increased capacity in the longer term, however,


The Panamax constraint has been applied far wider than in the dry bulk sector, however, and there is potential for carbon reduction in optimisation of hulls


other sectors, through the that may previously have been


preserving the draught requirements presented by many loading and discharge ports.


The ability to increase beam presents the opportunity to produce a lower first cost than is possible with the increase in length that is required for a conventional Panamax ship to maximise capacity within the beam constraint.


It also presents the opportunity to reduce


operating costs. A “Mini-Cape” vessel of around 85,000 dwt can offer on average a 10% increase in deadweight with a 5% reduction in power requirement compared to a traditional Panamax. A 110,000 dwt dry bulk carrier offers an estimated potential 9% unit cost reduction over a traditional 80,000 dwt Panamax ship.


Fuel consumption, and therefore CO2 production, will benefit from the improved efficiency of hull forms that the relaxation of the beam constraint will permit. Capacity in Panamax vessels is achieved primarily by increasing length, which results in less efficient hull designs than could be achieved through increase in beam rather than length. The removal of the beam restriction will remove the need for this compromise in ship design. First estimates presented in this paper indicate a fuel saving of 5.4% due to the improved hull form. When combined with the potential to increase ship size it is estimated that a 110,000 dwt vessel offers a 16% saving in fuel per tonne-mile of cargo carried, and therefore pro rata saving in CO2 production compared to a traditional Panamax ship.


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