Objectives  In order to study the laws of the propulsion shafting deformation and variation of the bearing load of a underwater vehicle under various conditions,

  Methods  a mixed finite element model of the shaft system and the underwater vehicle was established, with a underwater vehicle as the research object, to which the realistic load and boundary conditions were applied under three conditions including on the slipway, at the pier and underwater to calculate the hull deformation respectively and the deformation of the bearing and the bearing load were extracted. Taking the connecting line of the bearing 1 and bearing 3 as the reference line, the relative deformation of the bearing under three conditions was obtained.

  Results  The analysis results show that, for this underwater vehicle, the relative deformation of the centerline of the shaft system, its size and the changing trend of the bearing load are different under the conditions from the slipway to the pier and then to the underwater; the initial deformation of bearing 2 of the shaft system on the slipway is preset to be 0.090 9 mm upward, so that the shaft system is in ideal state on the underwater.

  Conclusions  The study in this paper can provide reference for the subsequent shafting alignment.