To much of the commercial side of the bunker market, debunkering looks like a delivery run in reverse. Capt. Qaisar Qayyum, a Master Mariner and Independent Maritime & Bunkering Adviser who spent some two decades managing bunker operations at Fujairah — one of the world's three largest bunkering hubs alongside Singapore and Rotterdam — latterly as General Manager, Bunkering Operations (UAE) for Vitol Bunkers, has spent much of his career correcting that assumption.

"Debunkering is not merely the reverse of bunkering," he writes in a new paper published by Ship & Bunker. "It is one of the few operations within the marine fuel industry that simultaneously tests almost every element of operational capability."

The full paper, Debunkering: Why One of the Marine Fuel Industry's Most Demanding Operations Reveals the True Value of Operational Judgement, is available for download from Ship & Bunker here.

The fundamental difference between bunkering and debunkering lies in how each operation begins. A routine delivery starts with everyone's interests broadly aligned: the supplier wants to complete the stem, and the vessel needs the fuel for its onward voyage. Debunkering, by contrast, starts with relationships already under strain — fuel quality under investigation, machinery repairs altering the vessel's requirements, chartering changes rendering the original stem unnecessary, or even the ownership of the fuel itself requiring clarification.

The operation therefore "begins not with the movement of fuel but with the reduction of uncertainty," Qayyum writes. That starting position elevates the significance of every record made along the way, because a debunkering is conducted in circumstances where any log, sample, or email may later have to support a technical investigation or a legal claim. The stakes surrounding such documentation have only grown since the IMO's 2020 global sulphur cap introduced a wider array of very low sulphur fuel oil (VLSFO) formulations, each with distinct stability and compatibility characteristics that have generated new categories of quality disputes.

"Many disputes were not caused because an operation had been performed incorrectly," he writes. "Rather, they arose because the operation could no longer be reconstructed with sufficient clarity to satisfy all parties involved."

Memory fades over the weeks and months a dispute takes to develop, he notes. Tank measurements, transfer logs, sampling records, survey reports, and contemporaneous communications together form an evidential chain that allows events to be understood in their proper sequence.

Sampling receives similar emphasis in the paper. Beyond laboratory analysis, samples that are obtained, witnessed, sealed, and documented correctly build confidence between the parties during the operation itself. Deficiencies in the sampling process complicate commercial discussions even when the fuel ultimately proves satisfactory.

On the same logic, Qayyum argues that the independent surveyor's greatest contribution "was not the production of reports but the confidence those reports inspired."

His broader argument is that fuel removal serves as the industry's most revealing stress test, exposing organisational weaknesses that remain hidden during routine deliveries. Every debunkering, he writes, was an opportunity to observe "how an organisation actually functioned when certainty gave way to uncertainty." With the bunker industry now navigating the early introduction of biofuel blends and other alternative fuels — each bringing new handling, storage, and quality-assurance variables — the operational discipline Qayyum describes is likely to remain relevant well beyond the conventional fuel era.