Single-Pour/Single Pass Loading: An Innovative Concept for a New Generation of Ore Carriers

Bulk Carriers have been developed since 1950 to carry large quantities of non-packed commodities such as grains, coal and iron ore. Nowadays, there are some 5,000 bulk carriers around the world and this number points to some concerns that affect owners of these types of ship and ports. One of these problems is the big waiting time at the ports that reaches 12% of the global fleet around the world at any given moment. At Brazilian iron ore ports the time waiting average was of 6–8 days during 2006–2008. A concrete example is the VALE operation that responds from mineral resources exploration to mineral resources delivery, passing through mines, railroads, seaport terminals and shipping business, forming a logistic chain that can not be interrupted by the expected growth in trade and consequent port congestion. In view of this, PROJEMAR and VALE faced the challenge of designing ore carriers in such a way that it would not interfere with the logistics chain by delaying other ships at the loading or discharge terminal. As the cargo operation is taken as the initial point of the design conception, the expected final product is a ship able to safely take loading rates as high as 16,000 tons of ore per hour, with each hold loaded in one pour and the ship fully loaded in one pass, resulting in fewer pours into the holds of the ore carrier, faster loading operations and, consequently, a significant economy for the ship owner and for the port. The amount of extra steel needed over conventional designs: less than one percent. The fundamental idea of this new concept, which PROJEMAR calls “single-pour, single-pass” design, is a method of ballast control that is synchronized with the cargo loading, scientifically deballasting the ship during loading in a way that balances the forces induced by the incoming cargo. Potential hull loading stress problems can occur due to the manner in which ore cargoes are loaded and due to the amount of cargo which is loaded in an individual hold. To avoid the creation of any unacceptable stresses in the ship’s structure, loading studies considering the planning of cargo loading and discharging operations, maximum allowable and minimum required mass of cargo for each hold and for adjacent holds as a function of the draught at mid-hold position in form of hold mass curves, calculations of still water shear forces and still water bending moments for each port loading condition and structural analysis are required to be developed on the early design stages. This ship loading concept is creating a new generation of ore carriers in such a way that the main class societies are nowadays developing new specific class notation dedicated to these ships. The purpose of this paper is to present the “single-pour, single pass” concept development and how it has been applied to the design of the new 400,000 DWT ore carriers that are being built for VALE in Chinese and Korean shipyards, and to the 80,100 DWT Bauxite Carrier that are being built for LOG-IN in Brazil. The “single-pour, single pass” concept was also partially considered on the design of 12 VLCCs that are being converted to VLOCs for VALE in China with PROJEMAR’s design.