عباس دشتی منش

In the current paper, a mathematical model is developed for performance prediction of hard-chin boats which can be used for both semi-planing and planing ranges. The proposed model is established by 2D T theory and implements pressure distribution over the length of the hull in order to compute the forces. To determine the forces in the semi-planing range, a function is proposed for the non-dimensional length at which the transom effects appears. Three components of drags consisting of frictional, induced, and spray drags are considered in the required computations. These calculations are performed using an iterative method and satisfying two equilibrium equations. The validity of the proposed method is verified through the comparison of the predicted trim angle and resistance against the available experimental data. Based on these comparisons, it is observed that the proposed method display favorable accuracy in both semi-planing and planing regimes. The method is then used to study the variation of hydrodynamic and hydrostatic forces as the hull makes a transition from a semi-planing regime to a planing regime. In addition, different components of the resistance are investigated.