Ice Controllable Pitch Propeller - Strength Check Based on IACS Polar Class Rule

Abstract

While there are power saving and high thrust capability advantages of CPP (Controllable Pitch Propeller) for ice propulsion, the introduction of CP mechanism makes the propulsion system more vulnerable when operating in heavy ice conditions. In CPP designs, the recently released IACS URI3 – “Machinery Requirements for Polar Class Ships” provides the design forces on the propeller blade resulting from propeller-ice interaction. These design forces are also the source of the spindle torques, which can be used for the determination of CPP mechanism scantlings. In this paper, ice loads formulae in URI3 for open and ducted CPP will be adopted for an existing ice CPP for its mechanism check to evaluate the rationality of the Rule. To further explore the influence from different design principles on CPP scantlings, both the maximum life time ice load and the blade failure load provided in URI3 will be applied on the existing CPP to check its mechanism strength. The detailed comparison of the strength check outcomes provides very useful information for ice CPP design.