Evaluating the Influence of the Standard and Actual Centers of Gravity of the Typically Loaded Container on the Metacentric Height of a Container Ship

Abstract

Ensuring the proper stability of the vessel is the core of its safe operation. Metacentric height is one of the most important and most indicative criteria of stability. Accepted standard values of the container center of gravity are currently used for calculation of the metacentric height of a container ship. This is due to the fact that manual calculation algorithms and stability calculation programs are based on the use of the final value of the center of gravity of the container stack in each bay, but do not take into account the actual height of center of gravity of each individual container. The aim of the study is to compare the influence of the standard and actual center of gravity of the container on the metacentric height of the container ship. For this purpose, the recommended schemes for general cargo stowage in containers, given in the "Rules for the transport of goods in containers by sea", are analyzed in the paper. The heights of the actual centers of gravity of containers for each case of cargo stowage are calculated. Experimental loading of a large-capacity container ship is carried out using standard and actual values of the containers centers of gravity heights. As a result, it is found that in the vast majority of cases, the containers center of gravity is below the accepted standard position. It is concluded that the actual center of gravity of the container has a significant influence on the metacentric height of the container ship, so that its actual value becomes greater than the standard calculated value. The expediency of specifying the heights of the actual center of gravity of the container in cargo documents for further consideration when drawing up a cargo plan and calculating stability is justified. Recommendations for updating some regulatory documents governing and concerning position of the container center of gravity are proposed.