Influence of Lightweight Change on Ship Performance

Abstract

An influence assessment of lightweight change on Energy Efficiency Existing Ship Index/Energy Efficiency Design Index performance for two supramax bulk carriers is presented in this paper. The study covers a variation of lightweight from 100% to 85% with the step of 5% reduction. The influence on ship performance is determined through deadweight, reference speed, and engine load. In one part of the work, deadweight is considered to be constant, so the study covers the impact of displacement change on ship speed and power, while in the other one, displacement was kept the same so that the direct influence of deadweight on performance indices was considered. Due to displacement change, a new power curve should be derived, and for this purpose, the Holtrop-Mennen method has been used to predict total resistance. Estimated results show that an increase in speed can be up to 0,7% for the same power and a reduction in power up to 2,6% for the same speed. An increase of a deadweight affects the performance indices up to 3,2%.