In vessel operations, a Bunker ROB Survey is commonly carried out when a vessel takes bunkers, changes charterers, or is delivered or redelivered. The surveyor’s role is not simply to record the quantity of fuel onboard, but to establish the ROB at a specific point in time based on an appropriate measurement method and supporting documentation.
The Case
During a bunker survey, the surveyor was appointed to determine the quantity of fuel remaining onboard before and after bunkering.
Before taking measurements, the surveyor checked the fuel tank list, tank condition, sounding pipes, tank calibration tables and information relating to any internal fuel transfer onboard.
ROB was measured for each relevant tank under the actual onboard conditions. Sounding readings were recorded together with fuel temperature and cross-checked against the tank calibration table to determine the corresponding volume.
One critical factor in this case was the timing of the measurement.
The pre-bunkering ROB must represent the fuel condition at the agreed measurement time before bunkering commences. If the vessel continues consuming fuel or transferring fuel between tanks during this period, such activities must be recorded to avoid using figures representing different operational conditions in the subsequent calculation.
Verification After Bunkering
After completion of bunkering, the surveyor carried out a further ROB measurement of the relevant tanks.
The post-bunkering figures were cross-checked against:
- Pre-bunkering ROB;
- Quantity delivered as stated in the Bunker Delivery Note;
- Fuel consumption during the relevant period;
- Any internal fuel transfers between tanks;
- Fuel temperature and measurement conditions at the time of survey.
In principle, the post-bunkering ROB should be reasonably explainable through the relationship of pre-bunkering ROB + bunker quantity received – relevant fuel consumption or transfer.
Where a discrepancy is identified, the surveyor should not immediately conclude that a bunker shortage has occurred. The measurement method, timing, fuel temperature, tank calibration data, internal transfers and relevant operational records should first be reviewed.
The Value of the Survey
In practice, the Bunker Delivery Note is not the sole basis for determining the actual ROB onboard. The BDN records the delivered quantity under the delivery documentation, while the ROB Survey establishes the quantity of fuel physically remaining onboard at the time of survey.
For On-Hire, Off-Hire or Redelivery surveys, bunker figures established at the relevant handover point may become an important basis for reconciliation between Owners and Charterers.
Therefore, the value of a Bunker ROB Survey does not lie solely in the final figure. It lies in the chain of evidence supporting that figure: the measurement time, measurement method, onboard conditions, individual tank readings, supporting documents and any irregularities observed during the survey.
Observe – Measure – Record – Reconcile.
Evidence first. Conclusion second.
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