Remain On Board (ROB) Monitoring: Fuel Balance for Every Vessel

MANTRAZ remain on board (ROB) monitoring keeps a running fuel balance for every vessel in the fleet. It is for owners, operators and fleet managers who need to know how much fuel is on board before they plan the next voyage or order the next bunker, without chasing the vessel for a figure.

The question every plan starts with

How much fuel is on board? It sounds simple, but the answer often means asking the vessel, waiting for a report and adding figures together by hand. When consumption, bunkers and corrections are tracked in different places, the ROB figure is only as good as the last time someone reconciled them all.

How ROB monitoring works in MANTRAZ

MANTRAZ keeps the balance running for you. It starts from a start balance, subtracts what the engines burn, adds every bunker, and applies adjustments so the balance matches the tanks:

ROB = start balance + bunker − consumption ± adjustment

The balance is logged daily, weekly or monthly, so you can see not only what is on board now but how it got there.

Where each part of the balance comes from

Each term in the formula comes from data MANTRAZ already collects:

• Consumption comes from the engines. Main engine fuel is measured by flowmeters on the supply and return lines. Auxiliary engine fuel is usually estimated from running hours, and reports keep measured and estimated fuel apart.
• Bunker is added for every bunkering. During the delivery, MANTRAZ measures flow rate, density, temperature, mass and volume.
• Adjustments bring the calculated balance in line with what is actually in the tanks, so small differences do not build up over time unnoticed.

Because the balance is built from these pieces, a change in ROB can always be traced back to what caused it: a day of heavy running, a bunker, or a correction.

Planning with a number you can trust

A reliable ROB changes two everyday decisions. Before a voyage, you know whether the fuel on board covers it. Before ordering a bunker, you know how much room there is and how much the vessel actually needs, instead of ordering on an estimate that may be days old.

The daily, weekly and monthly logs also help when looking back: which periods burned the most, when bunkers came in, and where adjustments were needed.

Who uses it

Fleet managers use ROB to see fuel on board across every vessel at once. Operations teams use it when planning voyages. Whoever orders bunkers uses it to decide when and how much to order. Because the figure is kept up to date by the system, everyone works from the same balance.

See it on the map

The Remain On Board chapter on the MANTRAZ homepage follows a demo vessel's fuel balance over several days, including a bunker. To see a running ROB balance for your own fleet, contact the team for a demo.