Water-lubricated bearings are critical components in marine propulsion systems, directly influencing vessel operational safety and reliability. This study investigates the mechanism of water film pressure distribution under different slat profiles by establishing a fluid-structure interaction (FSI) analysis model of the bearing. Systematic numerical calculations were carried out for various slat types and groove arrangements. The effects of flat, convex, and concave slats on bearing load capacity and wedge-shaped water film pressure distribution were compared. The results indicate that concave slats generate a larger positive pressure zone in the circumferential direction and exhibit more continuous water film pressure distribution. In the studied 24-slat bearing, the difference in maximum water film pressure between the slat-down and groove-down arrangements was only 1%. In contrast, the local groove configuration increased maximum water film pressure by 17.6% compared to the other two arrangements, also demonstrating superior axial pressure distribution. In conclusion, the combination of concave slats and a local groove design significantly enhances the load-carrying capacity and operational reliability of large-scale water-lubricated bearings.