Some Notes on Approximate Methods of the Calculation of Resistance Increase of Ships in Waves

Abstract

In this paper some approximate methods calculating resistance increase of ships in waves, i. e., Joosen's, Wahab's, Gerritsma's, Boese's and strip methods, are discussed. Drifting forces are calculated by these methods, but non-linear wavemaking resistances and diffraction forces are neglected. Resistance increases have been calculated for the three ship forms (Series 60 parent forms: C_B=0.8, 0.7, 0.6) and the results are compared with experimental results. It is found that the results of calculation roughly explain the experimental results, but, usually, they seem to be smaller than experimental values in fat ships and larger in slender ships. The best method for calculating resistance increase with sufficient accuracy is not yet decided.