Impact of New Bow Shapes on FSICR Power Requirements

Abstract In the Baltic Sea, merchant ships receive icebreaker assistance during the winter period based on their Ice Classes, which are granted based on the Finnish Swedish Ice Class Rules (FSICR). The FSICR set requirement for e.g. the ship minimum power demand to secure an adequate ice performance of ice-classed ships. The rules have been developed based on cumulative experiences on the winter navigation in the region with ships having traditional ice-going vessel design. Recently, growing interest on sustainable transportation has led to new emission restrictions for merchant ships. This has generated new approaches for the ship bow design, especially for ships mainly operating in open water and only occasionally in ice. Some recently built ice-capable merchant ships have open-water-optimised bow shapes that substantially differ from traditional bow shapes of ice-going vessels. Instead of traditional low stem angles, the bow angle can be vertical or close to vertical. Our recent research indicates that the current FSICR procedures may not evaluate the brash ice channel resistance of these modern bow shapes correctly. To secure the uniform ice class classification, this paper reflects the conclusions from our channel resistance research on the ice class rules power requirements and suggests improvements to current rules.