Investigation into the ship motion induced moisture migration during seaborne coal transport

The inherent moisture in a coal cargo constantly migrates under the dynamic ship motion during maritime transport. The moisture often builds up at the bottom of the cargo. The accumulated water, if not removed sufficiently by the bilge well, can cause safety concerns during a voyage and difficulties during cargo unloading. The study presented in this paper aims to develop a program to investigate the moisture migration within coal cargoes in order to assess and eliminate shipping risks. The moisture migration phenomenon is initially modelled by adopting the classic infiltration theory, and considering the ship motions experienced by bulk carriers. An experimental method is developed to empirically characterise the moisture migration of a coal sample under simulated shipping dynamics. A predictive model is also developed to estimate the total moisture migration in a full size cargo by properly scaling up the experimental results. The model was validated by bilge well log collected from actual coal shipping voyages from Australia to international destinations.