The problem: paying for fuel you never received
The classic bunker fraud is short delivery — the ship is billed for more tonnes than actually reach its tanks. The best-known trick is the “cappuccino effect”: air is blown into the fuel during delivery so it froths, inflating the volume measured by traditional tank soundings. The buyer pays for litres of air. Other methods include tampered temperature readings, rigged tables and manipulated sounding tapes.
The fix: mass flow metering (MFM)
A mass flow meter measures the actual mass of fuel passing through the delivery line — not volume, which air and temperature distort. Because it weighs the fuel, entrained air cannot fake the reading, and the delivery is logged continuously and printed. It closes the cappuccino loophole almost entirely.
Singapore made MPA-approved MFM mandatory for residual fuel (MFO) deliveries from 1 January 2017, and for distillates from 1 July 2019, under the TR48 metering standard. It was the first port to do so at scale, and quantity disputes fell sharply. Rotterdam and Antwerp-Bruges are set to make MFM mandatory from 2026, extending the model to Europe's largest hub.
Where MFM does and doesn't help
MFM addresses quantity. It does not address quality — that is what fuel testing and the bunker delivery note are for. And MFM is not tamper-proof in every port: cases have surfaced of attempts to interfere with meters, which is why an attentive chief engineer and, on larger stems, a third-party quantity surveyor still matter even where MFM is fitted.
How to protect yourself
Bunker at ports with approved MFM where you can. Have the chief engineer witness the meter totaliser and the seals before and after delivery. Note the meter reading on the BDN. On large or high-value stems, appoint a quantity surveyor. And buy from suppliers with a reputation to protect — the cheapest quote is no bargain if the tonnes are short. Seven Ocean supplies at MFM-regulated hubs and coordinates surveys where you want the extra assurance.
Frequently Asked Questions
What is the cappuccino effect?
Blowing air into the fuel during delivery so it froths and reads as a larger volume on traditional tank soundings — the ship pays for air. Mass flow metering, which weighs the fuel, defeats it.
Where is mass flow metering mandatory?
Singapore since 2017 for residual fuel and 2019 for distillates, under the TR48 standard. Rotterdam and Antwerp-Bruges are set to make it mandatory from 2026.
Does MFM guarantee I get the right quantity?
It largely closes the air-entrainment loophole and has cut disputes sharply, but meters can still be interfered with. A vigilant chief engineer, sealed meters, and a third-party quantity surveyor on big stems remain good practice.
Does MFM check fuel quality too?
No. MFM is about quantity only. Quality is verified through representative sampling and laboratory fuel testing, and recorded on the bunker delivery note.