Propeller Ice Interaction – Theory and Practise

Abstract Propeller ice loads refer to the forces exerted on ship’s propeller when it meets ice. This interaction is particularly relevant where ships frequently encounter ice floes and ridges. The forces generated during ice impacts can be quite significant compared to open water operation and can affect the structural integrity of the propeller and the entire propulsion system. The ice properties such as thickness, strength, salinity and temperature play major role in determining the magnitude of ice induced propeller loads. Understanding the propeller ice loads is essential for ensuring the safety and efficiency of ships operating in ice covered waters. This paper describes the basic principles regarding the design of ice-strengthened propellers. The design principles evolved from experience-based knowledge to analytical calculations of ice loads on the propeller blade. The different methods will be presented and evaluated by comparing to practical experience and measurements. Constraints and shortcomings with different methodologies will be discussed. Comparison will be made between different classification rule requirements. This paper will also discuss the differences on ice loading on pushing type propellers with conventional shaft line icebreakers and modern pulling propellers used in azimuth type thrusters.