Abstract

This paper presents operational experience and ice measurement results from Finnish Icebreaker Polaris propulsion system. Icebreaker Polaris applies a novel three propulsion unit concept. During the shipbuilding period an extensive ice load measurement system was installed on two of the Azipod units. The paper will present key findings from the measurements from the winter periods 2017-2018.

The target of the ice load measurement campaign is to increase the designer knowledge of propulsor ice loads in different ship operations. The purpose is to understand in more detail the load distribution for component life estimations and clarify differences between bow and stern propulsor ice loads and frequencies. Due to non-linear load distribution in propulsor at extreme loads, strain gauges were installed at two levels in propulsor hull.

This paper will highlight some measurement results of propulsion system behavior during the ice trials and long term measurements from the winters 2017 and 2018. The full-scale ice operation data collected in the Baltic Sea ice conditions can be further utilized in a development vessel and its propulsion system of heavy polar icebreaker type.

The measurement campaign onboard the Polaris is planned to continue during coming winters. The aim is to collect statistical ice load data to improve the understanding of the fatigue and ultimate design loads. One of the goals is also to clarify how much load the bow mounted propulsion unit will experience compared to the stern units. Based on the measurement results so far, we can conclude that icebreaker with bow mounted Azipod propulsor can be operated without limitations in all ice conditions, just like all the other icebreakers in the Baltic.

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