Investigation of Container Stowage in Cell Guides of Open-Top-Container Vessels

Abstract

Open-top container vessels for faster cargo handling process appears at the beginning of the 1990s. Removing the hatch cover in this design allows containers to stack continuously from the double bottom to the top tier. Cell guides support containers in the cargo hold area, but containers at the top end of cell guides are secured by twistlock and lashings. Unfortunately, it is not feasible to use standard twistlock within cell guides. It causes most of the loads from containers above the cell guides to be transferred to the uppermost container in the cell guides. Roll motions of the vessel induce tilting loads to the container. Since the tilting support condition of uppermost container in the cell guide is not initially considered in container design, this condition significantly increases the risk of container failure. A finite element analysis is performed to investigate the container stowage in cell guides. StowLash and Ansys software are utilized for this study. This study reveals that due to the different heights of container depth in such cell guides, the uppermost container in cell guides has a meaningful impact on the transverse load but not the vertical load. The shorter container depth in cell guides induces a higher transverse load. In this study, Ansys and StowLash have better comparison results with 900mm container depth in cell guides. On the other hand, adding internal lashing on the uppermost container in cell guides can reduce the transverse movement and transverse load but raise the corner post load. In addition, having a higher depth of the aft part container in the cell guide than the fore container can reduce the transverse loads and movement.