Static and dynamic stability of a polar ship in the arctic region with ice accumulation

Abstract

The harsh and complex marine environment of the Arctic region poses significant challenges for polar ships, particularly in cases where ice accumulates on ship surfaces, which can severely influence vessel stability. This study presents a comprehensive analysis of both static and dynamic stability for a polar ship subjected to ice accumulation, a topic of critical scientific importance and engineering relevance for ensuring the safety of Arctic navigation. Specifically, a simplified model for predicting ice accumulation weight is proposed, which uses the spray rate, icing coefficient, and hull area segmentation to facilitate accurate and efficient forecasting of ice accumulation on ships. The effects of ice accumulation on the static stability of a polar ship during several different hours of icing events are compared with those of a no-ice case under typical marine meteorological and hydrological environmental conditions, and the requirements in the IMO IS code are verified. Additionally, to evaluate dynamic stability, a roll motion mathematical model is developed to predict the roll response of a polar ship with ice accumulation, with roll damping parameters obtained via free-decay computational fluid dynamics (CFD) simulations. Furthermore, the average conditional exceedance rate (ACER) method is applied to conduct an extreme value analysis of the roll response under the action of wind and waves, enabling a thorough assessment of the ultimate dynamic stability with ice accumulation. This study systematically analyzes the stability loss of a polar ship induced by ice accumulation, which can contribute to the design of polar equipment and the safety of polar navigation.