Bunker Survey for On-Hire & Off-Hire Vessel Assessments
Independent bunker quantity verification and Remaining On Board (ROB) assessment for vessel delivery, redelivery, on-hire and off-hire operations.
Why Bunker Quantity Matters During On-Hire and Off-Hire
Bunker quantities form an important part of many vessel delivery and redelivery assessments. At the commencement or completion of a charter, the quantity of fuel remaining on board may have a direct commercial significance under the applicable charter-party or contractual arrangements.
An independent bunker survey provides documented measurement evidence of the fuel quantities observed at the time of attendance. The survey can help owners, charterers, operators, brokers, P&I interests and claims handlers establish the bunker position at vessel delivery or redelivery.
What Is an On-Hire or Off-Hire Bunker Survey?
An on-hire bunker survey is generally performed in connection with vessel delivery to a charterer, while an off-hire bunker survey may be performed during or after vessel redelivery depending on the contractual arrangement.
The survey records the applicable fuel quantities on board and provides an independent basis for comparing the observed bunker position with the quantities declared by the parties or stated in relevant vessel documentation.
The exact terminology and commercial treatment of bunker quantities depend on the applicable charter-party, sale and purchase agreement, bunker supply arrangement or other contractual requirements.
Typical On-Hire / Off-Hire Bunker Survey Scope
ROB Verification
Independent measurement and documentation of the Remaining On Board fuel quantities at the agreed time of delivery or redelivery.
Fuel Tank Soundings
Sounding or ullage observations of applicable fuel tanks using available vessel procedures and tank calibration information.
Tank Calibration Review
Review of applicable tank calibration tables and information used to convert measured levels into fuel quantities.
Temperature Information
Recording of available fuel temperature information where relevant to the agreed quantity calculation methodology.
Bunker Documentation
Review of Bunker Delivery Notes, bunker records and other available documentation relevant to the bunker position.
Quantity Reconciliation
Comparison of observed quantities with declared bunker quantities and relevant contractual or vessel records.
On-Hire Bunker Survey Process
Vessel Delivery Information
Review of vessel identity, location, delivery timing, applicable charter-party requirements and requested survey scope.
Initial Fuel Measurements
Applicable fuel tanks are measured and the observed quantities are recorded together with relevant measurement conditions.
Documentation Verification
Available Bunker Delivery Notes, previous bunker records, tank calibration information and vessel documentation are reviewed where relevant.
ROB Statement
The measured bunker position is documented and reconciled with the available declared ROB information.
Off-Hire and Redelivery Bunker Survey Process
At vessel redelivery, the bunker survey establishes the fuel position applicable to the agreed survey time and contractual requirements. Independent measurements can help identify differences between the observed bunker quantity and quantities declared by the parties.
Redelivery Attendance
Confirmation of vessel location, attendance timing and the agreed bunker survey scope before measurements commence.
Fuel Tank Measurement
Applicable fuel tank soundings or ullages are recorded in accordance with the agreed measurement procedure.
Quantity Calculation
Measurements are assessed using the applicable tank calibration information and documented calculation methodology.
Final Bunker Position
The resulting bunker position is documented for comparison with the applicable delivery or redelivery requirements.
Key Documentation Reviewed During a Bunker Survey
| Documentation | Review Purpose |
|---|---|
| Charter-Party / Contractual Terms | Identification of the applicable bunker quantity, measurement, delivery, redelivery and reconciliation requirements. |
| Bunker Delivery Note | Review of declared bunker grade, quantity, density information and delivery documentation. |
| Tank Calibration Tables | Verification of the vessel information used to convert measured tank levels into quantities. |
| Previous ROB Records | Comparison of declared fuel quantities with the independently observed bunker position. |
| Bunker Measurement Records | Review of soundings, ullages, temperatures and other relevant measurement information. |
| Vessel Operational Records | Review of relevant bunker transfer or fuel consumption records where necessary for reconciliation. |
Factors That Can Affect Bunker Quantity Calculations
Bunker quantity calculations depend on the quality and suitability of the available measurement and vessel documentation. Several technical factors may influence the resulting quantity assessment.
Tank Calibration
The accuracy and applicability of the tank calibration tables used for the quantity calculation are important to the assessment.
Measurement Conditions
Vessel trim, list, tank condition, accessibility and the measurement method may affect the recorded bunker quantities.
Temperature
Fuel temperature information may be relevant to quantity calculations depending on the contractual methodology and documentation available.
Fuel Distribution
The distribution of fuel between tanks and the operational condition of the vessel may need to be considered when establishing the overall bunker position.
Timing of Measurement
The time of measurement should correspond as closely as practicable with the agreed delivery or redelivery condition.
Documentation Accuracy
Differences between vessel records, supplier documents and physical measurements may require additional technical review.
Bunker Quantity Reconciliation
A bunker survey may involve reconciliation between the independently observed fuel quantity and the quantity declared in the applicable documentation.
Where a material difference is identified, the survey report should document the measurements, assumptions, available supporting information and calculation methodology rather than automatically attributing the difference to a particular cause.
Bunker Quantity Discrepancies During Charter Delivery
Bunker quantity discrepancies can arise for a variety of reasons, including differences in measurement procedures, tank calibration information, timing, vessel condition, fuel temperature, documentation or declared quantities.
An independent survey does not automatically determine contractual liability. Instead, it provides technical measurement evidence that can assist the parties and their advisers in evaluating the bunker position.
Measurement Difference
Comparison between independently observed measurements and previously declared bunker quantities.
Documentation Difference
Identification of inconsistencies between BDN information, vessel records and other available documents.
Calculation Difference
Review of the calculation methodology, assumptions and tank calibration information used to establish the quantity.
Further Investigation
Where appropriate, additional records or technical evidence may be reviewed to understand the source of an apparent discrepancy.
Bunker Survey and Fuel Quality
It is important to distinguish bunker quantity verification from fuel quality analysis.
A bunker survey can document fuel quantities, available density information, sampling arrangements and relevant bunker documentation. It does not by itself constitute chemical or laboratory fuel-quality analysis.
Bunker Sampling During On-Hire / Off-Hire Attendance
Where included in the agreed scope, a surveyor may attend representative bunker sampling and sealing arrangements and record the available sample identification and documentation.
Sample Identification
Recording of sample identification information and relevant bunker documentation.
Sealing Information
Documentation of applicable sample sealing arrangements and associated evidence.
Chain of Custody
Recording of available chain-of-custody information where required for subsequent fuel-quality investigation.
Laboratory Testing
Independent laboratory analysis should be arranged separately when chemical fuel properties or specification compliance need to be established.
What an Independent Bunker Survey Report Can Provide
Vessel Details
Vessel identity, location, attendance information and agreed survey scope.
Measurement Records
Applicable tank soundings, ullages, temperatures and observed bunker information.
Quantity Calculation
Documented bunker quantity calculations using the available vessel information and agreed methodology.
Documentation Review
Review of BDN information, vessel records and other relevant documentation available during the survey.
Discrepancy Identification
Documentation of apparent differences between measured and declared bunker quantities.
Supporting Evidence
Relevant photographs, records, measurement sheets and other evidence where included in the agreed scope.
Who Uses On-Hire and Off-Hire Bunker Surveys?
Shipowners
To document the vessel's bunker position during delivery, redelivery and charter transitions.
Charterers
To obtain independent bunker quantity evidence for charter delivery and redelivery assessments.
Vessel Operators
To maintain an independent technical record of bunker quantities associated with vessel operations.
P&I and Claims Interests
To support investigation of bunker quantity discrepancies and related commercial or contractual claims.
Technical Reference Framework
The bunker survey methodology should be applied according to the specific vessel, operation, contractual requirements and available technical documentation.
Independent Technical Oversight
Independent Survey
PAMS Pacific Admiralty Maritime Services provides independent marine surveying and technical consultancy services for shipowners, charterers, operators and maritime stakeholders.
Technical Measurement
The bunker survey focuses on independent measurement, documentation and reconciliation within the agreed scope.
Evidence-Based Reporting
Measurements, observations, documentation and apparent discrepancies are presented in a structured technical report.
Commercial Support
Independent technical evidence can assist owners, charterers, operators and claims interests during bunker quantity discussions.
About the Technical Author
Technical Content Review
Last Technical Review
July 2026
Review Frequency
Technical content is reviewed periodically to reflect applicable maritime requirements, marine fuel practices and relevant technical guidance.
Bunker Survey On-Hire / Off-Hire FAQ
What is an on-hire bunker survey?
An on-hire bunker survey is an independent measurement and documentation service used to establish the vessel's bunker quantity at or around the agreed delivery condition.
What is an off-hire bunker survey?
An off-hire or redelivery bunker survey documents the applicable fuel quantity remaining on board at or around the agreed vessel redelivery condition.
Why is ROB verification important?
Remaining On Board verification provides an independent record of the vessel's fuel quantities and can assist in reconciling the bunker position against contractual or declared quantities.
Does PAMS review charter-party bunker requirements?
Where included in the agreed scope, PAMS can review the applicable contractual bunker requirements and use them to establish the technical survey scope and reporting basis.
Can PAMS investigate bunker quantity discrepancies?
Yes. PAMS can review measurements, tank calibration information, Bunker Delivery Notes, vessel records and other available evidence to document apparent bunker quantity discrepancies within the agreed technical scope.
Can a bunker survey determine fuel quality?
No. A bunker quantity survey does not constitute chemical or laboratory fuel-quality analysis. Fuel quality disputes may require representative sampling, chain-of-custody arrangements and independent laboratory testing.
Can PAMS attend bunker sampling?
PAMS may attend representative bunker sampling and sealing arrangements where this is included in the agreed survey scope. Laboratory analysis is a separate activity.
Does an independent bunker survey determine contractual liability?
No. The survey provides independent technical measurement and documentary evidence. Contractual interpretation and liability remain matters for the parties and their contractual or legal advisers.
Engineering Reference Notice
This article describes the general principles and methodology of bunker surveys associated with vessel on-hire, off-hire, delivery and redelivery assessments. The actual survey scope depends on vessel type, location, access, tank arrangement, measurement systems, calibration information, available documentation, contractual requirements and client instructions. Quantity calculations depend on the accuracy and suitability of the available measurement information. A bunker survey does not constitute laboratory fuel-quality certification unless separate testing arrangements are specifically included.
Related Bunker Survey Resources
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