Preventing Vessel Fuel Theft: Measure, Reconcile, Alert

Vessel fuel theft is one of those problems many operators suspect and few can prove. Fuel is usually the largest running cost of a vessel, it is easy to move and easy to sell, and it is often recorded by hand. Preventing vessel fuel theft is less about catching someone in the act and more about building a record where fuel cannot go missing without the numbers showing it.

Why fuel losses are hard to see

On many vessels the fuel record is a chain of manual figures: a supplier's delivery note, a sounding before and after, a daily consumption estimate based on running hours, and a ROB written in the noon report. Each link has a normal margin of error. When those margins are wide and nobody compares the links against each other, a real loss can sit inside the noise for months.

That is also why accusations are a poor starting point. A discrepancy can come from a leak, a meter out of calibration, a sounding taken at the wrong trim, or a simple unit mistake. Treating every gap as theft damages trust with honest crews and suppliers. Treating every gap as normal lets real losses continue. The goal is a system where each gap gets an explanation.

Common patterns of vessel fuel theft

Without going into how it is done, the patterns the industry talks about fall into a few broad groups:

• Short delivery at bunkering. The paperwork shows more fuel than actually reached the tanks.
• Fuel leaving the vessel off the record. Fuel is transferred out of the tanks, often during idle time, at anchor or during stops that were not in the plan.
• Inflated consumption. Reported consumption is set higher than what the engines actually burned, so that the book ROB still matches the tanks after fuel has gone missing.
• Record adjustments without a reason. Soundings, logs or adjustments are changed after the fact with no clear explanation of why.

In Indonesia, the informal term "solar dikencingin" is often used for this kind of loss. Whatever it is called, the common factor is the same: it relies on fuel figures that nobody checks against an independent measurement.

Prevention starts with measurement

The strongest defence is to measure fuel at the points where it moves, instead of estimating it afterward.

Measure what the engines burn. Consumption estimated from running hours multiplied by an assumed rate leaves room for any number to look plausible. A flowmeter on the engine turns consumption into a measured figure. On most main engines this needs meters on both the supply and the return line, because part of the fuel sent to the engine flows back to the tank unburned.

Measure what the vessel receives. A bunker checked only against the supplier's note and a before-and-after sounding is hard to verify. A flowmeter on the bunker line, read together with the sounding, gives two independent figures to compare with the delivery note.

Know where the vessel was. A position record makes unplanned stops, long idle periods and unusual meetings at sea visible, so they can be matched against the fuel record for the same hours.

Reconciliation: comparing the numbers regularly

Measurement only helps if someone compares the figures. A regular reconciliation checks that:

• start ROB, plus bunkers received, minus measured consumption, matches the tanks;
• every adjustment has a reason, a name and a time;
• consumption per hour or per nautical mile stays consistent for similar voyages and conditions;
• stops and idle time on the track match the fuel used in the same period.

Done daily rather than monthly, reconciliation keeps each gap small enough to explain while people still remember what happened.

Alerts and physical controls

Some problems should not wait for the next reconciliation. A sensor that stops sending data, for example, deserves attention the same day, whether the cause is a fault or tampering. Physical controls still matter too: sealed tank openings and valves, restricted access to fuel lines, clear procedures for transfers, and a second person present when fuel is moved or measured.

Where MANTRAZ fits

MANTRAZ gives operators the measured side of that record. Main engine fuel is measured by flowmeters on the supply and return lines, and bunkers are measured for flow rate, density, temperature, mass and volume, with the bunkering log setting the target against the flowmeter total and the tank sounding. The ROB balance keeps start balance, bunkers, consumption and adjustments together, and every adjustment records a reason, who made it and when.

Vessel tracking sends each vessel's position every 60 seconds, with track replay of 1 to 14 days to review stops. Alerts are raised when a device stops sending data, and each vessel's connection is marked Online, Offline, No GPS or No Sensor, so a quiet sensor does not go unnoticed.

To see how measured fuel and reconciliation look on data similar to your fleet's, request a MANTRAZ demo.