Impact of forced roll motion on the ice resistance of modernicebreaking bow geometries
International Conference on Ocean, Offshore and Arctic Engineering (OMAE 2020)
Contribution to Conference
Following the development of low friction hull coatings andazimuthing propulsion for icebreaking vessels, the developmentof auxiliary systems for reducing ice resistance fell from focusof research. One of these systems is comprised of active heelingtanks which induce a forced roll motion on the icebreaker. Todayit is not fully understood how effective or even useful such sys-tems would be for the icebreaking performance in combinationwith a modern icebreaking hull form. In this study, the impactof active heeling systems on level ice resistance is investigatedby performing ice model tests with an icebreaker representingthe latest design generation. The level ice thickness used in themodel tests corresponds to the maximum continuous icebreakingcapability of the evaluated vessel in multi-year ice conditions.Additionally, a calculation method is developed to predict the im-pact of forced roll motion on the ice resistance. The calculatedprediction is evaluated against the model-scale data. Finally, theeffectiveness of the active heeling system is evaluated from anengineering perspective: does the active heeling system reducethe power demand, or would the same result be achievable byincreasing the propulsion power accordingly. It was found thatthe roll motion impacts the ice resistance in level ice. The maininfluence in this regard lies with the tank volume and metacen-tric height of the icebreaker. Additionally, it was observed thatan optimum heel angle dependent on the ice condition can bedetermined which is not necessarily the highest one achievable.The case study predicts a reduced power demand for a modernicebreaker hull form in harsh ice conditions.