Performance analysis of ship moving in old ice channel

Abstract

Navigation in old ice channels filled with broken (or brash) ice is a frequent operational scenario for ice-going ships, and at the same time insufficiently studied. The purpose of the present work is to study the change of ship propulsion performance in brash ice as compared with open-water conditions taking Yury Topchev, one of the ice-going ships currently in service, as a case study. Two related tasks to the propulsion performance study have been performed in the paper: 1) the brash ice resistance assessment of ship moving in the channel, and 2) analytical assessment of the change in propeller in thrust and power demand, in brash ice conditions as compared with open water. Numerical simulations have shown that a brash ice layer with the thickness equal to 0,2 propeller diameter reduces propeller efficiency by up to 20 %. Propulsion performance calculations for Yury Topchev, including the assessment of both hull resistance and propeller hydrodynamics have shown that in brash ice with the thicknesses of 1 and 3 m (0,125 and 0,375 draft) the maximum speed of this ship might drop as low as by 25 % and 40 % respectively. The results of this study may be used in planning of long ship voyages in ice conditions, when the changes in propulsion performance due to brash ice become especially relevant.