The study delves into the lift-to-drag ratio characteristics of arc-shaped wing during water entry, employing a time-domain boundary element method under fully nonlinear boundary conditions. The wing's entry commences from a single contact point, followed by a rapid expansion of the wet surface, and this would pose a notable challenge for numerical simulation. To address this, a stretched coordinate system technique is deployed to extend the physical domain, effectively managing numerical difficulties at the initial stage. Additionally, the auxiliary function method is utilized to derive pressure distribution. The investigation encompasses varying deadrise angles, attack angles, and body curvatures to discern their effects on the lift-to-drag ratio. Notably, the study finds that the lift-to-drag ratio is predominantly influenced by the effective attack angle. Moreover, the effective deadrise angle and surface curvature of the body also play significant roles in shaping the lift-to-drag ratio. These findings underscore the multifaceted nature of factors contributing to the hydrodynamic performance of curved foils during water entry.