Computer Modelling the Reclaim Action of a Self-unloading Vessel

In recent years there has been a steady increase in the number of self unloading ships involved in the world shipping trade. This paper focuses on unloading difficulties encountered on board the M.V. River Yarra, a vessel converted to self-unloading configuration in late 1991 which is now working around the Australian coastline. These difficulties arose when discharging cohesive materials such as gypsum, salt and slag. Due to the design of the reclaimer units a portion of the cargo within each hold was not positively reclaimed. This resulted in large unstable sections of cargo which caused damage to the reclaimer unit when they collapsed. The investigation involved the development of computer based solid models of each hold, the determination of strength and frictional characteristics of the various cargoes and a review of the slope stability of the cargo within the hold. From the solids model, the amount of cargo positively reclaimed and the capacity lost due to alterations to the holds were calculated. Measurement of the frictional and bulk strength characteristics allowed an analysis of the product stability within the hold during reclaim.