In the last decade, the popularity of hydrofoils on marine craft has increased significantly, particularly in the yachting industry and on recreational products. With a widespread push for more efficient, low-emission transport, commercial applications for fast ferrying of passengers and cargo are also being explored. Hydrofoil design poses a significant challenge to naval architects, due to complex hydrodynamics and operating regimes which are challenging to analyse (Faltinsen, 2005). Marine engineers employ a range of tools to study hydrofoil hydrodynamics, ranging from experimental methods in water tunnels and tow tanks; to simulation-based approaches such as computational fluid dynamics (CFD) and other numerical models. To reduce cost, much of the preliminary design is done using the latter (Newman, 2018). Accurate and validated methods for simulating hydrofoils are therefore crucial for engineers seeking to develop efficient and performant designs. In this study, we showcase the development, validation, and application of a numerical lifting-line (LL) model for simulating hydrofoil hydrodynamics (Chernyshev et al., 2024). This model was adapted to simulate free surface and wave-making effects by employing a Green’s function for a source in steady motion under a free surface, originally derived by Newman (1987). A rectangular NACA4412 hydrofoil submerged one chord-length beneath the free surface was simulated at Reynolds numbers between 2.57×10^5 and 2.06×10^6 (Froude numbers between 0.5 and 4) and the results between using the LL model and a Reynolds-Averaged Navier Stokes model were compared. Overall reasonable agreement between LL and RANS was seen when comparing the lift, drag and moment coefficients across all simulated Froude numbers. This increased our confidence that the LL model can be relied upon for dictating design choices and direction at the preliminary stage of design. Its key advantage over RANS was its efficiency with compute resources, permitting extensive parametric design studies (e.g. exploring how different taper/twist combinations affect the resistance) and optimisation. However, great care should be taken when interpreting the LL results as the theoretical models employed, especially for the free surface effects, were difficult to validate and still showed considerable discrepancies with RANS, particularly when simulating regimes with intermediate Froude numbers.