Energy efficiency and environmental concerns are compelling shipping companies to consider improving vessels fuel efficiency. Reducing fuel consumption which almost considered as the largest part of operating cost has a beneficial environmental impact by reducing greenhouse gas emissions.

There are many ways for optimizing shipboard energy efficiency, but sometimes the simplest changes offer the largest gains. This study is focusing on operating a ship at optimum trim in order to keep fuel consumption at minimum. Trim optimization studies are not limited to new ship designs; they can easily be implemented on existing ships.

In this study, a bulk carrier is targeted for research in order to predict         optimal trim configuration which leads to less resistance to minimize fuel  usage. The results showed that even small adjustment of the trim will lead to significant fuel savings due to large resistance variation. The relation between the resistance variations and ship speed, loading condition, and stability is studied. In order to interpret the change in resistance, the physics behind less fuel consumption due to changed propulsive power when trimming a vessel has been analyzed.

The reference bulk carrier has been investigated at full and partially loaded drafts at different speed range. It was concluded that a propulsive power can be reduced by more than 10% only due to a slight afterward trim. This led to 15% saving in fuel and overall operations savings as high as 3 to 4%.