Ice-induced impact loads on the propeller blades of vessels operating in polar waters represent a notable hazard to ship propulsion systems. Industry guidelines determine the maximum allowable ice-induced propeller moments, but these loads are not practical to measure directly. Recent studies have implemented deterministic inversion methods to determine these impact-induced moments from torque measurements on the propulsion shaft. This study considers this inversion problem from a stochastic perspective. Bayesian inversion is used, first, as a means of determining the optimal regularisation parameters, and second, as an avenue to explore the contributions to uncertainty in the inverted ice loading values due to the linear inversion model. The method is implemented for two sets of shaft-line measurements recorded on the SA Agulhas II, a polar class PC-5 research and supply vessel, via a lumped-mass model for the forward response signal. Using more sophisticated simulation results as prior information for the model uncertainty, it is shown that inverted ice-induced propeller moments around 20% below the industry guideline maximum loading of 1009.9 kN m correspond to a 1% probability of ice-induced moments exceeding this limit. This finding is significant, given the number of propeller impact events for the SA Agulhas II that approached this limit during recent voyages, and highlights the need for considering design specifications for propulsion systems in ice-faring vessels from a risk perspective.

在极地水域操作的船只的螺旋桨叶片上的冰引起的冲击载荷对船舶推进系统构成了明显的危害。行业准则确定了冰激进螺旋桨的最大允许力矩，但是这些载荷无法直接测量。最近的研究已经实施了确定性的反演方法，以便根据推进轴上的扭矩测量值来确定这些由冲击引起的力矩。本研究从随机角度考虑了该反演问题。首先，使用贝叶斯反演作为确定最佳正则化参数的一种方法，其次，作为探索线性反演模型对反演冰负荷值不确定性的贡献的途径。该方法适用于SA Agulhas II上记录的两组轴线测量，极地级PC-5研究和补给船，通过集总质量模型获得前向响应信号。使用更复杂的模拟结果作为模型不确定性的先验信息，结果表明，倒冰引起的螺旋桨力矩比行业准则的最大载荷1009.9 kN m低约20％，对应于冰引起的力矩超过此限制的概率为1％ 。考虑到SA Agulhas II的螺旋桨撞击事件在最近的航行中接近该极限，因此这一发现意义重大，并强调了从风险角度考虑制冰船推进系统设计规范的必要性。结果表明，倒冰引起的螺旋桨力矩低于行业准则最大负荷1009.9 kN m的20％左右，相当于冰引起的力矩超过此限制的概率为1％。考虑到SA Agulhas II的螺旋桨撞击事件在最近的航行中接近该极限，因此这一发现意义重大，并强调了从风险角度考虑制冰船推进系统的设计规范的必要性。结果表明，倒冰引起的螺旋桨力矩低于行业准则最大负荷1009.9 kN m的20％左右，相当于冰引起的力矩超过此限制的概率为1％。考虑到SA Agulhas II的螺旋桨撞击事件在最近的航行中接近该极限，因此这一发现意义重大，并强调了从风险角度考虑制冰船推进系统的设计规范的必要性。