Understanding the effect of assumptions on shell plate thickness for arctic ships

The presence of ice requires specially constructed ships. The biggest challenge in this aspect is ice loads on ship’s hull: processes of deformation and fracture of ice are not fully understood and ice geometry and mechanical characteristics can vary dramatically over a few meters. Regardless of which ice-strengthening requirements that are chosen as the basis for hull structural design, engineers make assumptions about the ship-ice interaction scenario, but ship-ice interaction scenarios outside rules requirements can be fatal for both operators and the environment. Concerning safe design, there is a need for better understanding the ice loads in conjunction with the models for assessing capacity of structural elements. This paper contributes to highlighting the current differences between guidelines of the International Association of Classification Societies for Polar Ships (IACS, 2011) and of the Russian Maritime Register of Shipping (RMRS, 2014) for ice loads and plate thickness requirements. The goal of this study is to summarize the assumptions that underlie design formulations and ice class factors in order to deepen our understanding of the rule formulae, their background and limitations