Abstract: To forecast the hydrodynamic properties of tunneled planning boats and to examine the water-air distribution inside the tunnel, Computational Fluid Dynamics (CFD) simulations are performed focusing on hull resistance and navigational motion, with the findings subsequently compared to towing tank test data. The resistance and navigational motion of the tunneled planning boat are analyzed across a range of volume Froude numbers. Additionally, the influence of pressure distribution within the tunnel's flow field on the boat's attitude are investigated and the characteristics of water-air distribution within the tunnel's flow field are captured. Both simulation and experimental results reveal that hull resistance peaks at a volume Froude number of 2, subsequently declining thereafter. Once the volume Froude number surpasses 3, resistance exhibits a linear increase with velocity. Under these circumstances, the water and air within the tunnel become thoroughly mixed, leading to an optimized hull attitude. The primary factor contributing to the peak pitch and heave observed in the boat during the transitional speed range is attributed to the pressure distribution within the tunnel.