Bunker

Bunkers are the fuel oil stored in dedicated tanks within a ship's double-bottom or wing spaces and consumed by the main engine, auxiliary generators, and boilers throughout the voyage. The term derives from the coal bunkers of the steamship era and now encompasses the full range of marine fuels from heavy residual fuel to distillate grades. Accurate bunker surveys at loading and discharge ports are essential for commercial voyage accounting and for flag state enforcement under MARPOL Annex VI, which requires ships to carry a Bunker Delivery Note and fuel oil sample for at least three years. Bunkering operations carry significant pollution risk: accidental overflow or hose failure can discharge tonnes of oil into harbour waters within minutes. MARPOL Annex I requires that all bunkering be logged in the Oil Record Book Part I, and port state inspectors routinely cross-check quantities received against consumption records. Engineers measure tank soundings before, during, and after bunkering and monitor trim changes to prevent structural overloading of the hull.