Hull form optimization of displacement type deep-vee vessels based on nonlinear programming

Nonlinear programming is used to optimize the hull form of displacement type deep-vee vessels with bulbous bow in this paper. The total resistance is chosen as target function; the offsets of ship form are the optimizing variables; hull form displacement and variation range of offsets are used as restrictions. The effect of sailing pose was considered to calculate the total resistance, and the wave-making resistance of which was obtained by using Michell integration. The following findings are obtained: there are different effects of resistance reduction among different station with hull optimization, and it is favorable for the reduction of wave-making resistance to optimize the hull form on station 0 to 6 and station 14 to 20 The number of chine line, should be considered in the hull form optimization, has significant influence on the resistance performance. An improved hull form which exhibited a reduction rate of 17.15% on wave making resistance, 9.52% on frictional resistance, and 12.56% on total resistance, was obtained at given ship speed. It is applicable and reliable to adopt nonlinear programming for the hull optimization of displacement type deep-vee vessels.