Determining optimal ship speed and fuel consumption depending on ship's cargo amount: An application on Ro-Ro ships

Fuel consumption effects merchant ships both economic and environmental ways. As known, fuel cost contributes more than half of seaway transport costs. Therefore, reducing fuel cost is the very essence of shipping companies. On the other hand, due to ships' fuel consumption there are serious enviromental consequences to handle by shipping companies. Nowadays, most of merchant ships use heavy fuel oil (HFO) as propulsion fuel which causes greenhouse emissions due to its high carbon content. For this reason, International Maritime Organization (IMO) has issued some strict regulations to mitigate harmful gas emissions taken its source from merchant ships. In case of not to comply with these regulations, shipping companies have to face serious monetary penalties by authorities. At the present time ship speed is the main affecting factor of fuel consumption. Consequently, in order to eliminate both environmental and economic disadvantages of fuel consumption, shipping companies should perform optimal speed onboard. In this study; two sister ships voyage data, belonged to the year of 2015, was used. These ships are Ro-Ro cargo ships and belong to a liner shipping company. Firstly, total 236 days voyage data, including ship daily speed, daily fuel consumption amount, ballast water amount, total ship cargo amount, sea state and wind state, were examined. An optimization method, named Genetic Algorithm (GA), was used to determine variety optimal speeds depending on current ship load and wind-sea states. In conclusion, those optimal speed values were evaluated and interpreted on applicability on model ships.