Bunkers (weight item)

Bunkers are the fuels carried for propulsion and auxiliaries, fuel oil, marine gas oil, and increasingly LNG or methanol, entered as a deadweight item rather than a lightship item because they are consumable and variable. In the displacement balance, bunker mass at full load is part of the deadweight that the ship is designed to lift on top of cargo, stores, and fresh water. Bunker weight drives endurance, so trading fuel-tank volume against cargo space is a design decision. Bunker quantity and its longitudinal distribution also shift the trim and the still-water bending moment, so the loading manual covers the departure-full and arrival-empty bunker conditions.