How to Verify Marine Fuel Bunkering

Why bunker verification matters

Every bunkering has three numbers that are supposed to agree and often do not: the target quantity ordered from the supplier, the volume a flowmeter actually measured going into the tanks, and the tank sounding taken before and after. When those three numbers drift apart — a common story in marine fuel bunkering — the gap is either a real loss (a leak, a spill, a miscalibrated meter) or a supplier short-delivery, and without a record tying the discrepancy to a cause, it becomes a dispute nobody can resolve with data.

The usual way bunker discrepancies get missed

Without dedicated monitoring, verifying a bunker usually comes down to comparing a delivery note against a manual sounding, taken by hand, hours apart, with no continuous record of the flow itself. A slow leak or a pump that keeps running a few minutes after the target is reached does not show up in a before-and-after sounding — it only shows up if something was measuring the whole time the fuel was flowing.

Measuring the bunker itself, not just before and after

MANTRAZ measures flow rate, density, temperature, mass and volume through every bunker, with the live total refreshed every 60 seconds during the delivery and exportable to Excel afterward. Because the flowmeter is measuring continuously, an overflow alarm reaches the crew and the office when the tank nears its limit — not after it has already happened.

Target vs flowmeter vs sounding, side by side

After every bunkering, MANTRAZ's bunkering log sets the target quantity against the MANTRAZ flowmeter total and the tank sounding taken before and after, and shows the discrepancy in both KL and percent. Seeing all three numbers next to each other, rather than reconciling them manually days later, is what turns "the numbers don't match" into a specific, checkable discrepancy.

Recording the reason, not just the number

A discrepancy on its own does not say what happened. MANTRAZ records corrections as adjustments with a reason — a pipe leak, spillage, a meter calibration issue or a supplier dispute — along with who logged it and when. That means a bunker record is not just "we received X litres less than ordered," it is "we received X litres less, logged as a supplier dispute, by this person, at this time." If a dispute with a supplier does happen, it starts from that record instead of from memory.

What this looks like in practice

• Flow rate, density and temperature are measured continuously during delivery, not sampled once.
• The live total updates every 60 seconds so the crew can watch the delivery in progress.
• Target, flowmeter total and sounding are compared automatically after every bunkering.
• Every adjustment has a reason and an owner, timestamped.

Getting started

If accurate bunkering records matter to your fleet, request a demo to see the bunkering log on data similar to yours.