A Fundamental Study on Motion Characteristics and Cargo Handling Efficiency of the Large-Scale Floating Coal Transshipment Station

Abstract

This paper describes the motion characteristics and cargo handling efficiency of the Large-Scale Floating Coal Transshipment Station (LFTS). Indonesia is a main country supplying coal in the Asia-Pacific region, it is important to ensure a stable coal supply to Japan. Because the topography of the seabed near East Kalimantan Island, Indonesia’s main coal production area, is shallow, it is difficult for bulk carriers to reach the coast. Therefore, LFTS is proposed, which will be used as a relay base between coal-barging barges from land and bulk carriers offshore. By installing LFTS, improvement of coal transport efficiency is expected. In considering feasibility of the LFTS system, it is important to know the cargo handling operation rate in the target area, LFTS can load 500,000 tons of coal and the draft will fluctuate greatly depending on the loading condition of coal. Therefore, when the draft is shallow, the freeboard becomes large and resonates with long-term component of the wind load and when the draft is deep, the wave force and fluid force including the slowly varying wave drift force affect the fluctuation. Also, LFTS and bulk carrier are large-scale structures, the fluid forces acting on both affect each other, so the influence of hydrodynamic mutual interference between two floating bodies cannot be ignored. In this study, fluid analysis in consideration of the hydrodynamic mutual interference of LFTS system is conducted. And, response analysis of LFTS and a bulk carrier in irregular wave which considered compound external forces such as wave load and slow varying wave drift force, wind load, tidal current was performed. As a result, it was confirmed that the motion response of LFTS was not upset because LFTS was large. Therefore, without considering the motion response of the LFTS, the cargo handling efficiency is calculated from the response analysis results of the bulk carrier and the oceanic condition of the setting sea area. As a result, the cargo handling efficiency is satisfied in the state where bulk carrier is installed leeward of LFTS, and it was confirmed that the LFTS system could be operated satisfactorily if the installation was appropriate.