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In most of methods and among Savitsky's semi experimental method, deadrise angle is assumed constant or used its amount in cross section of gravity center. In fact the deadrise angle of high speed craft is variable in longitudinal direction of hull. According to pervious assumptions for the deadrise angle, real physic of Problem didn’t model. In this paper, hydrodynamic resistance per weight is calculated by development of Savitsky’s semi experimental method and has been shown that results of present method have more accurate than results of Savitsky’s semi experimental method at comparison with empirical results. Also results of present method are good agreement with the empirical results over a wide range of volumetric Froude numbers. Then, optimum effective parameters such as position of gravity center, beam and rate of deadrise angle variation is determined by using genetic algorithm method. Objective function is considered resistance per weight in optimization that it is calculated in first part of the paper. Dynamic and static stability are as constraints of optimization that dynamic stability includes transverse dynamic stability and porpoising. Finally, Optimum answers group is presented for use of naval architect in concept design of monohull high speed craft.

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In this article, rigid wedge water entry problem under different conditions are evaluated using numerical scheme. It continues to be one of the fundamental issues raised in the hydrodynamics studies and known as a reference for the study of slamming phenomena. The exact calculation of the pressure caused by the slamming phenomenon can be used to analyze the appropriate structural analysis of the ships. In the current study, important variables such as speed and fluid pressure is investigated using computational fluid dynamics method based on the open source OpenFOAM code by numerical solution of the governing equations of tow phase fluid. In order to verify the simulation results obtained from this research, he values of the maximum pressure and t he location and exact time of its occurrence and also pressure coefficient distribution at the impact region have been compared by experimental results of other studies. These investigations have been utilized at different impact velocities and angles. By comparing the numerical results and experimental values, an error was found in the range of 2 to 9%. In addition, variables affecting the pressure applied to the wedge such as water entry velocity and different deadrise angles have been studied.