Experimental investigation on the natural frequency and damping coefficient of the roll from vessel response in random seas

<p>Autonomous shipping is inevitably the future of sea transportation which requires accurate decision-making<br> systems. Analysis of big data as a key element to develop these decision-making systems is much easier than before. The precise prediction of vessel roll response, as a critical component of ship motions, by directly calculating hydrodynamic parameters from vessel response during the voyage, would tremendously aid in the real time adjustments to avoid dangerous situations the vessel would encounter.<br> This investigation aims to extract the natural period and damping coefficient of the roll from vessel response in random seas. Experimental tests were conducted to record the roll motions of vessel models, P&O Nedlloyd Hoorn container ship and Midi Mak Marad F bulk carrier, in random waves at Australian Maritime College Model Test Basin. The natural period obtained from the vessels’roll response in random seas were in close agreement with the one obtained from the vessels’ roll decay test with negligible percentage error of under 1% for both models. Random Decrement Method (RDM) was used to produce roll decay from random vessel response and estimate the damping coefficient of the models. <br> The estimated damping ratio from RDM show the good agreement with roll decay tests. This great achievement can help us to precisely predict the vessel roll response in random seas in order to avoid dangerous situation. </p>