Speed-Based Fuel Consumption and Efficiency Potential of the Pioneer Passenger Ship KM. Bung Tomo on Route R-16: An Analysis of Engine-Room Log-Book Data

Indonesia's pioneer ships burn subsidised fuel, yet their requests are often based on nominal daily figures from ship specifications rather than measured consumption. This study estimates the fuel demand and speed-related saving potential of KM. Bung Tomo, a 1,257 GT passenger ship serving pioneer route R-16 (836 nautical miles, 10-day round voyage) from Kalianget, Indonesia. Engine-room log-book data for one sailing day were combined with engine particulars and a propeller-law power–speed model calibrated to the logged main-engine consumption. The ship used 3,312 L per sailing day: 2,880 L in the main engines (120 L/h, about 31% of combined MCR) and 432 L in the generators (18 L/h, about 19% of one generator's rating). The calibrated model places the logged consumption at about 6.4 knots, at which one round voyage needs about 19,900 L (23.8 L per nautical mile; about IDR 135.5 million; 53.8 t CO₂ on a fossil-diesel basis). This matches the 20,000 L delivered per bunkering and the 21 kL requested for Voyage 16, whereas the specification figure applied over ten days would nearly double the estimate. Raising speed to 8 knots would add about 43% per voyage, while sailing at 6.0 knots would save about 2,000 L per voyage, or roughly 60,000 L and IDR 411 million over a 30-voyage contract, within the route's schedule margin. Low generator loading points to further savings. The fuel balance for the observation period could not be closed from available records, which makes record-keeping a precondition for efficiency management on small subsidised ships.