eng Science and Education Publishing International Journal of Physics 2333-4576 2019-06-10 7 1 21 26 10.12691/ijp-7-1-4 IJP2019714 article Hassan Ghassemi gasemi@aut.ac.ir 1 Hassan Bahrami 1 Alireza Vaezi 1 Mohammad Aref Ghassemi 1 Department of Maritime Engineering, Amirkabir University of Technology, Tehran, Iran Trim-tab is a device for controlling the trim and improves the performance of the planing boat. It is installed at the stern of the hull to adjust the longitudinal center of pressure (LCP). This paper is presented to minimize the resistance of the planing boat using trim-tab. Savitsky’s method is employed to calculate the resistance. The chord of trim-tab is defined constant but the span is changed. The longitudinal center of gravity (LCG) is constant but LCP is varied at each speeds. By using the trim-tab, the LCP and LCG are adapted and the optimum trim angle and minimum resistance are calculated. The results of optimum trim angle, total resistance and angle of trim-tab at different speeds are presented and discussed. http://pubs.sciepub.com/ijp/7/1/4/ijp-7-1-4.pdf trim-tab minimum resistance planing boat savitsky’s method