When fuel efficiency is at stake, along with the reduction of the environmental foot print of air pollution, a need is presented to estimate a ship's fuel consumption for a forthcoming voyage, and means for decision making and for cost saving. This paper suggests an operational approach for obtaining an accurate fuel consumption and speed curve, on the basis of major factors affecting it, namely, ship’s draft and displacement, weather force and direction, hull and propeller roughness. A statistical analysis on 418 noon reports of a Pure Car and Truck Carrier case ship is carried out and the influence of the above factors is calculated. As expected, stronger wind and head weather increases the fuel consumption, and the difference between several weather conditions could be quantified. A simple and accurate algorithm is proposed in order for ship owners, managers and operators to be in a position to apply the suggested method on their fleet. Finally, applications of the structured algorithm are introduced with examples, in estimating the fuel consumption of the case ship for a future voyage, and also the same for a sister ship. Furthermore, voyage planning in several scenarios is proposed in order to assist the stakeholders with decision making aimed to fuel saving and environmental friendliness of their ships