Off-axis propeller loads create a significant problem for shaft alignment and bearing performance. As the propeller rotates through a non-uniform ship wake, it generates horizontal and vertical forces and moments that are difficult to support. In extreme cases (such as a high-speed turn), the off-axis loads can become as large as the mean propeller thrust and torque. As the bearing deflects to absorb these forces, and the shaft bends to absorb moments, metal-tometal contact can occur. This paper describes an approach to minimize such problems at the design stage. Computational Fluid Dynamics (CFD) predicts the propeller off-axes forces during a maneuver, and a Fluid/Structures Interaction (FSI) model predicts the resulting shaft stresses and deflections. Bearing forces and moments derive from CFD models of the oil film inside each stern tube bearing. Optimization finds the combination of design parameters that minimize metal-to-metal contact.

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