Bunker Delivery Note: MARPOL Annex VI Guide

The Bunker Delivery Note is the documentary spine of MARPOL Annex VI sulphur enforcement. It records the name, quantity, density, sulphur content, and flashpoint of every fuel oil delivery to a ship, must be retained on board for three years, and is accompanied by a sealed representative sample kept for at least 12 months. Port state control officers treat it as the first evidence they examine when checking fuel compliance.

A ship’s engineer signing a BDN is completing a transaction with legal consequences that stretch across multiple jurisdictions. The document is not a commercial invoice, though it often accompanies one. It is a regulatory record created under MARPOL Annex VI Regulation 18, and every field it contains was negotiated by IMO member states because a regulator needs it. Understanding what each field does, how the accompanying sample is taken and stored, and how the three sample types introduced in 2022 interact with port state inspection is the practical foundation for any ship officer, operator, or compliance manager handling bunkering operations.

Legal basis: MARPOL Annex VI Regulation 18 and Appendix V

MARPOL Annex VI entered force on 19 May 2005. Its Regulation 18 governs fuel oil availability and quality. Regulation 18.5 states that the fuel oil for combustion purposes delivered to and used on board shall be recorded by means of a bunker delivery note, and that note shall contain at minimum the information specified in Appendix V of the Annex. Regulation 18.6 requires the BDN to be kept on board and made readily available for inspection at all times for a period of not less than three years from the date of delivery.

Regulation 18.3 is the supplier’s obligation. It requires the fuel oil supplier to ensure that the fuel oil delivered does not exceed the relevant sulphur limit, and to issue a declaration confirming this. That declaration is a mandatory field on every BDN; without it, the document is non-compliant regardless of the quality of the product.

The current Appendix V text reflects a series of amendments. The 2010 revision of MARPOL Annex VI (adopted by MEPC.176(58)) restructured Regulation 18 and restated Appendix V. The most recent substantive change came through Resolution MEPC.362(79), adopted 16 December 2022 and in force from 1 May 2024, which added a mandatory flashpoint field to bring the BDN into alignment with SOLAS fire-safety requirements for fuel oil.

Scope: which ships and which deliveries

Regulation 18 applies to ships of 400 gross tonnage and above on international voyages. Administrations may apply it to smaller vessels at their discretion. The requirement covers all fuel oil delivered for combustion, including heavy fuel oil (HFO), very low sulphur fuel oil (VLSFO), ultra-low sulphur fuel oil (ULSFO), marine gas oil (MGO), and marine diesel oil (MDO). LNG supplied as fuel is generally handled under separate bunkering documentation, but where MARPOL Annex VI applies to the vessel’s propulsion fuel, the BDN framework applies.

A BDN is required for each separate delivery. If a ship receives two grades simultaneously through different manifolds, two separate BDNs must be issued. This matters in practice because VLSFO and HFO have very different sulphur contents, and a single combined document would obscure which grade flows to which service system.

Mandatory BDN fields under Appendix V

The table below shows the 10 mandatory fields in the Appendix V BDN as amended by MEPC.362(79), in force from 1 May 2024. The flashpoint field (item 9 in the amended numbering) is the only change from the 2010 version; items 1 through 8 and the supplier declaration (now item 10) are unchanged.

The quantity field deserves particular attention. MARPOL requires metric tons, not cubic meters or barrels. At most ports outside Singapore the quantity is derived from ullage measurements of the bunker barge’s tanks before and after delivery, corrected for temperature and trim. Singapore requires the quantity to be based on a mass flow meter reading rather than tank soundings. That distinction has direct implications for disputes, covered in a later section.

The density field exists because volume alone doesn’t prove the mass delivered. If a supplier measures volume and states density, a receiver can check the arithmetic. Density at 15°C is also the reference condition for the quality specifications in ISO 8217, which the fuel must typically meet under the sale contract. The BDN density does not prove ISO 8217 compliance on its own, but a density well outside the expected range for the stated grade is a red flag.

The sulphur content field is the single most consequential field from a port state enforcement perspective. It is the supplier’s own declared value. It must not exceed the applicable limit under Regulation 14: 0.50% m/m globally (in force since 1 January 2020, per the IMO 2020 sulphur cap) or 0.10% m/m inside an Emission Control Area (ECA). A BDN declaring 0.48% m/m does not prove the fuel is compliant, but one declaring 0.52% m/m on a global voyage is on its face a MARPOL violation for the supplier.

The flashpoint addition: why it matters

SOLAS Regulation II-2/4.2.1 prohibits the use of fuel oil with a flashpoint below 60°C (with specific exceptions for gas). Before MEPC.362(79), the BDN contained no flashpoint field. A PSC officer enforcing SOLAS had to rely on lab certificates or the fuel’s ISO 8217 specification, neither of which was required to accompany the BDN.

The new field requires either the actual measured flashpoint in degrees Celsius (per ISO 2719:2016, Procedure A for distillate fuels and Procedure B for residual fuels) or a statement that the flashpoint is at or above 70°C. The 70°C threshold gives a 10°C safety margin above the 60°C SOLAS floor, which reflects the reproducibility limits of the ISO 2719:2016 test method. If a supplier states “flashpoint at or above 70°C” and the ship’s own testing or a PSC sample shows a value below 60°C, the discrepancy is a SOLAS non-conformance as well as a contractual claim.

At the same time, the updated sampling circular MSC-MEPC.2/Circ.18 expanded the purpose of the MARPOL delivered sample: it now serves dual use for both MARPOL sulphur compliance checking and SOLAS flashpoint verification, and the minimum sample volume was increased from 400 ml to 600 ml to accommodate both tests.

The MARPOL representative sample: collection and chain of custody

MARPOL Annex VI Regulation 18.8 requires that every BDN is accompanied by a representative sample of the fuel oil delivered. This is the MARPOL delivered sample. It’s distinct from commercial samples that the ship and supplier take for quality verification under the sale contract.

The original IMO guidance for taking this sample was Resolution MEPC.96(47), adopted 8 March 2002. It was superseded by MEPC.182(59) (the 2009 Guidelines), which in turn has been revoked upon the issuance of MSC-MEPC.2/Circ.18 (agreed at MEPC 81). The current applicable guidance is MSC-MEPC.2/Circ.18.

Where sampling occurs

The MARPOL sample is to be taken at the receiving ship’s manifold during delivery. ISO 13739:2020 specifies that sampling occurs at the receiving ship’s manifold in the absence of any contrary port state requirement. This location matters because it captures the fuel as it enters the ship, not as it leaves the barge tank; any contamination or mixing that occurs in the bunker line between barge and ship manifold is captured in the manifold sample.

The sampling method is continuous drip sampling throughout the delivery. A continuous drip sampler draws a proportional trickle from the fuel flow over the entire delivery period, collecting into a single container. This produces a time-weighted composite that is representative of the entire parcel, not just a snapshot at one moment. Grab samples taken at the start or end of delivery are not representative for MARPOL purposes.

Sealing and labeling

At the end of delivery, the sample container is sealed with a tamper-evident seal in the presence of both the ship’s representative (typically the chief engineer or a nominated officer) and the supplier’s representative. Both parties sign the label. The seal number is recorded on the BDN itself, which is the mechanism by which the sample and the document are permanently linked.

Skuld’s guidance recommends that sample labels state: the location and method of collection; the delivery commencement date; the bunker tanker or installation name; the receiving ship’s name and IMO number; the signatures of both representatives; the seal identification number; and the fuel grade. These match the requirements in MSC-MEPC.2/Circ.18. A label that omits any of these fields weakens the evidentiary value of the sample if it’s later tested in a dispute.

The sample container must be glass or a material compatible with the fuel grade. Some light distillate grades can degrade plastic containers or leach plasticizers that contaminate the sample. Minimum size increased to 600 ml under MSC-MEPC.2/Circ.18.

Retention: 12 months or until substantially consumed

Regulation 18.8.2 requires the MARPOL sample to be retained on board until the fuel oil is substantially consumed but in any case for a period of not less than 12 months from the date of delivery. “Substantially consumed” in practice means when the associated delivery parcel has been burned through the main engines. A ship that bunkered 1,200 metric tons and still has 200 metric tons remaining cannot discard the sample even if 12 months have elapsed.

The Skuld guidance recommends storing samples outside the accommodation, in a cool, dry location shielded from direct sunlight. The paint locker is often cited as suitable because it benefits from fixed fire-suppression coverage. A dedicated MARPOL sample cabinet with an inventory log is the recognised best practice: the log records the delivery date, seal number, grade, and the date the associated parcel is substantially consumed, which is the trigger for disposal.

Three sampling points under MEPC.324(75)

Resolution MEPC.324(75), adopted at MEPC 75 and in force from 1 April 2022, extended the fuel sampling framework by introducing two new sample categories and requiring dedicated physical sampling points for them on board.

The three sample types

The in-use sample is taken at a point as close to the combustion machinery as safely feasible, downstream of the service tank (the day tank or settling tank from which fuel goes directly to the engines). It captures what the engines are actually burning at the moment of inspection. The onboard sample is drawn from a storage tank, which may contain fuel from a single delivery or a blend of parcels.

Physical sampling points: new construction and existing ships

MEPC.324(75) amends Regulation 14 of MARPOL Annex VI to require that ships of 400 GT and above fit, or designate, sampling points meeting defined criteria. For new ships with keel laid on or after 1 April 2022, the sampling points must be in place upon delivery. For existing ships, the requirement applied no later than the first IAPP Certificate renewal survey on or after 1 April 2023.

A designated sampling point must be: easily and safely accessible; located downstream of the service tank; as close to combustion machinery as safely feasible; shielded from heated surfaces and electrical equipment; and provided with suitable drainage to a drain tank or other safe location. The arrangement must be described in the vessel’s piping diagram or equivalent document and available for survey. Lloyd’s Register’s Class News 02/22 confirms that ships operating multiple fuel grades need separate sampling points for each grade in use simultaneously.

Where a ship already has a suitable valve or connection in the correct location, it can be designated as the sampling point without new hardware. Where no such connection exists, new pipework is required.

How PSC uses in-use and onboard samples

A PSC officer boarding under the Paris MOU, Tokyo MOU, USCG, or other regional regimes will, in the first instance, check the BDN and the IAPP Certificate against the declared fuel grade and the ECA or global sulphur limit applicable to the port. If the BDN declares a sulphur content consistent with the limit and the IAPP Certificate is in order, no sampling is required in a routine inspection.

If the officer has grounds for suspicion, they may collect an in-use sample from the designated sampling point. That sample goes to a laboratory. The compliance threshold for an in-use or onboard sample is not exactly the BDN limit: the Barbados Maritime Ship Registry Bulletin 345 specifies that fuel “should be deemed to meet the requirements, provided the test result does not exceed the specification limit plus 0.59R,” where R is the reproducibility of the ISO test method. For the 0.50% global limit, the tolerance is approximately 0.53% m/m. For the 0.10% ECA limit, approximately 0.11% m/m. These tolerances reflect measurement uncertainty under ISO 4259, not a permission to burn non-compliant fuel.

If laboratory analysis confirms non-compliance, the consequences include a deficiency notice, potential detention, requirement to debunker the non-compliant fuel, and a notification to the flag state and the bunker supplier’s port state. The BDN is central evidence in this process: the ship can argue it relied on the supplier’s declaration if the BDN shows a compliant sulphur figure, while the supplier faces action in its own licensing jurisdiction.

BDN use in port state control inspections

A PSC officer’s first check on fuel compliance is documentary. MARPOL Annex VI inspection guidelines (PSC Guidelines agreed under MEPC) direct officers to review the BDN alongside the IAPP Certificate, the Oil Record Book Part II (which records bunker operations), and the Engine Room Log Book entries for fuel changeovers on ECA transits.

The BDN review covers: whether the sulphur content declared is consistent with the fuel grade on board; whether the BDN relates to the same product described in the IAPP Certificate’s Fuel Oil Record; whether the 3-year retention period is being met for all BDNs on board; and whether the MARPOL sample’s seal and label match the BDN reference. A broken seal, a missing sample, or a BDN with a sulphur content above the applicable limit are each grounds for further investigation.

Some PSC regimes have introduced portable X-ray fluorescence (XRF) sulphur analysers that can produce an indicative sulphur reading from a fuel sample within minutes on board. These readings are not determinative: the results trigger further formal laboratory analysis but do not by themselves establish a violation. The Paris MOU’s guidelines describe these devices as screening tools.

In the US, the EPA enforces MARPOL Annex VI under the Act to Prevent Pollution from Ships (APPS). US Coast Guard officers may board vessels in US waters and EEZs and verify fuel compliance through BDN review and, where warranted, sampling. Penalties under APPS can include fines and criminal charges against officers and the company, making the evidentiary integrity of the BDN especially important on US voyages.

Fuel changeover records and BDN cross-referencing

A ship entering an ECA must switch from high-sulphur HFO to a compliant fuel before the ECA boundary (unless fitted with an approved exhaust gas cleaning system, commonly called a scrubber, which allows continued HFO use). The time and position of the fuel changeover must be logged in the Engine Room Log Book. A PSC officer will compare the changeover log entry with the BDN for the compliant fuel on board: if the BDN date pre-dates the ECA entry, the fuel was on board in time. If the quantity of compliant fuel delivered is insufficient to cover the ECA transit at the engine’s fuel consumption rate, that discrepancy is a clear ground for detailed inspection.

The fuel switching operations procedure, including the logbook notation and cross-reference to the BDN, is a documented routine that chief engineers should follow on every ECA transit. The BDN isn’t just a bunkering record; it’s the starting point for a chain of proof that spans the entire voyage leg.

Bunker quantity disputes and mass flow metering

The BDN quantity field is the focal point of most commercial bunkering disputes. A quantity dispute arises when the ship’s own tank measurements after delivery show a figure materially different from the metric tonnage on the BDN. “Materially different” typically means more than 0.3% to 0.5%, beyond what can be attributed to measurement uncertainty in tank ullaging.

The traditional quantity measurement method is tank gauging: the bunker barge’s cargo officer takes ullage readings of barge tanks before and after delivery, applies trim and temperature corrections from calibration tables, and derives a delivered quantity in cubic meters, which is then converted to metric tons using the density from the BDN. The uncertainty in this process is significant. Calibration table accuracy, temperature stratification in large tanks, and trim corrections all introduce error. An error of 1% on a 1,000-metric-ton delivery is 10 tons, worth roughly $6,000 to$8,000 at 2024 VLSFO prices of around $600 to$800 per metric ton.

Singapore’s mass flow metering mandate

Singapore, the world’s largest bunkering port by volume, addressed this problem by mandating the use of mass flow meters (MFM) for all Marine Fuel Oil deliveries from 1 January 2017, and for all distillate deliveries from 1 July 2019. The MPA-approved MFM system measures mass directly as fuel passes through the meter, without relying on volume-to-mass conversion or tank geometry. At the end of delivery, the MFM device prints a Bunker Metering Ticket (BMT) showing the delivered quantity. The MPA requires that “the delivered quantity of MFO stated in the Bunker Delivery Note shall be based on the bunker tanker’s MFM system as witnessed by the cargo officer, the chief engineer and bunker surveyor (if engaged).”

The BMT and BDN are issued together and signed by the barge cargo officer, the ship’s chief engineer, and the appointed bunker surveyor. If the MFM system fails during delivery, the barge operator must obtain MPA authorisation before reverting to tank gauging, and a separate BDN is issued under SS 600:2022 (the Singapore Standard for bunkering by tank gauging). This regulatory structure makes quantity disputes in Singapore materially harder to sustain, which is one reason the port processes over 50 million metric tons of bunkers per year with a relatively low formal dispute rate.

The Singapore Standard SS 648:2024 (superseding SS 648:2019) governs the technical requirements for mass flow metering in bunkering. MPA Port Marine Circular No. 12 of 2024 covers implementation of SS 648:2024 for all licensed bunker craft.

Outside Singapore, quantity disputes remain common. BIMCO charter party clauses and P&I club guidance consistently recommend that ships appoint independent bunker surveyors to witness bunkering and take independent measurements, because the BDN figure is the supplier’s figure and the ship has limited recourse once the chief engineer has signed it without protest.

Signing under protest and the letter of protest

If the chief engineer has grounds to believe the quantity stated on the BDN is incorrect but cannot delay or stop the signing process (for example, because the bunker barge has a sailing schedule to meet), the correct procedure is to sign the BDN with the notation “signed under protest” and immediately issue a written letter of protest to the supplier stating the grounds. The protest preserves the ship’s right to bring a claim without conceding the accuracy of the BDN. A BDN signed without protest is treated as an agreed receipt in most jurisdictions.

Fuel quality disputes and the MARPOL sample

Quality disputes, as distinct from quantity disputes, concern the specification of the fuel rather than the amount. The fuel may meet the sulphur limit on the BDN but fail ISO 8217 parameters such as cat fines (Al + Si content), total sediment potential, flash point, or water content. Engine damage from off-spec fuel is a P&I liability, and the MARPOL sample is central evidence.

The MARPOL sample, however, has limitations in quality disputes. It was collected at the manifold using a continuous drip method calibrated for MARPOL purposes, not for the full ISO 8217 test suite. The sampling point and method affect which parameters can be reliably measured. For example, water content measurements on a sample collected by drip sampling may not be representative of the bulk parcel.

For this reason, the Gard P&I club recommends that ships take at least five samples at every bunkering: one MARPOL sample at the manifold; one commercial sample for the ship’s own fuel testing programme; one commercial sample held on board as the ship’s reserve; one sample given to the supplier as the “co-sample” against which any dispute is settled; and ideally a fifth sample held with an independent third party. The MARPOL sample is the regulatory document; the commercial sample is the dispute evidence.

ISO 4259 governs reproducibility limits for petroleum product tests. When a ship’s analysis and the supplier’s analysis of the same batch produce different results, the test is “within reproducibility” if the difference between the two results is less than R, the reproducibility value for that parameter under the applicable ISO test method. BIMCO and IBIA guidance note that a result just outside the limit that is also within reproducibility of a compliant result doesn’t automatically confirm a violation; it triggers a further test or the referee laboratory procedure under ISO 4259-2. The BDN sulphur figure, however, is the supplier’s own declaration and is not subject to the reproducibility argument when comparing the declaration to the measured value in a lab.

The role of /wiki/bunker-quality-and-iso-8217 in disputes

The bunker quality and ISO 8217 article covers the full ISO 8217:2024 specification framework, including the parameters most commonly at issue in quality claims. The BDN interacts with ISO 8217 at the sulphur content and density fields, which appear on both documents, but the BDN does not certify ISO 8217 compliance. That certification comes from the supplier’s Certificate of Quality (CoQ), which is a commercial document issued under the sale contract, not a MARPOL document.

Electronic BDNs

MARPOL Annex VI does not specify paper as the medium for the BDN. The IMO has confirmed acceptance of electronic BDNs through MEPC.1/Circ.795, a consolidating circular that gathers unified interpretations to MARPOL Annex VI. The most recent revision publicly available, Rev.9, incorporates the additional interpretation agreed at MEPC 80 concerning Regulations 18.5 and 18.6.

An electronic BDN is compliant if it: contains the same Appendix V fields as a paper BDN; is protected from edits, modifications, or revisions after issue; and can be authenticated by a verification method acceptable to the relevant administration. Lloyd’s Register’s Class News 02/24 lists acceptable authentication methods as tracking numbers, watermarks, date and time stamps, QR codes, GPS coordinates, and other equivalent means.

The 3-year retention requirement applies equally to electronic BDNs. The ship must be able to produce the e-BDN on demand during PSC inspection, which in practice means it must be accessible on the vessel’s document management system, not just on the supplier’s server. A ship that relies on a cloud platform for BDN storage must have offline copies or be able to demonstrate retrieval capability without external network access.

Lloyd’s Register’s guidance also clarifies that electronic BDNs must reproduce the supplier’s signature or equivalent authentication in the declaration field. A supplier can’t issue a BDN with a declaration field stating “signed electronically” without specifying the authentication mechanism; that would be analogous to a paper BDN with a blank signature line.

Several commercial bunker management platforms now issue digitally signed BDNs with time-stamped GPS coordinates of the delivery position embedded in the document. Singapore’s digital bunkering initiative, announced by MPA with a target of mandating digital BDN issuance by 2025, points toward the direction the industry is moving.

Regulation 18 amendment timeline

The BDN requirements have been amended several times since MARPOL Annex VI entered force. Understanding the amendment history matters because ships sometimes encounter older BDN formats from suppliers in ports where local practice lags behind IMO requirements.

The original 2005 text of MARPOL Annex VI carried the BDN requirement with a shorter field list in Appendix V. The 2010 revision through MEPC.176(58), which restructured the whole of Annex VI and introduced the 0.50% global cap for 2020, also restated Appendix V in its current basic form with eight mandatory fields plus the declaration. MEPC.362(79), adopted 16 December 2022 and in force 1 May 2024, added the flashpoint field as item 9, renumbering the supplier declaration to item 10. The requirement for sampling points under MEPC.324(75) in force 1 April 2022 changed the physical infrastructure requirements on board ships but did not alter the BDN form itself.

The sampling guidelines followed a parallel track: MEPC.96(47) (2002) established the original procedure; MEPC.182(59) (2009) superseded it with updated guidance; MSC-MEPC.2/Circ.18 (agreed MEPC 81) revoked MEPC.182(59) and updated guidance to cover the dual MARPOL/SOLAS flashpoint purpose and the 600 ml minimum sample size.

Relationship to the IAPP Certificate and other records

The BDN doesn’t stand alone. Port state control officers and flag state inspectors read it alongside three other documents as a set.

The International Air Pollution Prevention (IAPP) Certificate is issued under MARPOL Annex VI to ships of 400 GT and above on international voyages. It records the applicable emission controls the ship is certified to meet. When fuel compliance is under scrutiny, the inspector looks at the IAPP Certificate for the ship’s ECA compliance status, then at the BDNs to see what fuel has been delivered, then at the Engine Room Log to see what fuel changeover records exist, and finally at the Oil Record Book Part II which captures bunkering operations.

Under MARPOL Annex VI Regulation 18.1, the fuel oil used on board must comply with the limits in Regulation 14. Regulation 14 sets the 0.10% m/m ECA limit and the 0.50% m/m global limit. The BDN sulphur field is how the ship demonstrates it loaded compliant fuel. But loading compliant fuel isn’t the end of the obligation: Regulation 18.2 requires that compliant fuel is actually used in the relevant sea area. The Engine Room Log’s changeover records bridge the gap between what the BDN says was loaded and what the ship was burning at any given position.

The interaction between the BDN and the imo-2020-sulphur-cap is direct: ships operating globally must hold BDNs showing 0.50% m/m or below for all fuel loaded after 1 January 2020, unless the vessel has an approved exhaust gas cleaning system. An exhaust gas cleaning system (scrubber) vessel may carry and burn HFO with higher sulphur content but must demonstrate scrubber certification and compliance with the washwater discharge standards under Resolution MEPC.184(59).

The cylinder oil base number and fuel sulphur interaction is another practical dimension. The correct cylinder oil BN for a two-stroke engine depends directly on the sulphur content of the fuel being burned. Operators set the feed rate and BN selection using the sulphur content from the BDN. An error in the BDN’s sulphur figure that propagates into the cylinder oil programme can cause underfeed (leading to liner wear) or overfeed (leading to deposits), making accuracy in the BDN not just a compliance matter but a maintenance matter.

BDN in the context of charter parties

Charter party clauses routinely specify that the charterer bears the cost of bunkers and that the vessel will consume fuel that meets certain specifications. A BDN is the document that both proves what was delivered and forms part of the evidence trail for off-hire claims, speed and consumption warranty disputes, and MARPOL non-compliance events.

Under a time charter, bunkers typically remain the charterer’s property. The chief engineer signs the BDN on behalf of the vessel, but the commercial dispute over quality or quantity runs between the charterer and the supplier, not between the shipowner and the supplier, unless the shipowner directed the bunkering. A time charter party clause specifying that the vessel shall always use fuel conforming to MARPOL requirements doesn’t solve a problem caused by a non-compliant delivery; it determines who bears the cost of the consequence.

BIMCO has developed standard bunker clauses for use in time charters, including provisions dealing with the taking of samples, the recording of seal numbers on BDNs, and the retention obligations. These clauses create a contractual layer on top of the MARPOL regulatory layer, ensuring that the commercial party responsible for bunkering also takes on the duty to document it correctly.

The demurrage interaction is more indirect but real. Bunkering delays at anchorage or berth that extend beyond the charterer’s laytime allowance can trigger demurrage claims. A bunker delay log that references the BDN delivery times provides the timestamping needed to calculate laytime consumed by bunkering.

Practical compliance checklist for ship operators

The BDN workflow involves multiple parties and a short window during which errors are hardest to correct.

Before bunkering begins, the chief engineer should confirm the nominated fuel grade, the expected quantity, the applicable sulphur limit for the current and next sea area, and whether a licensed bunker surveyor has been appointed. If the vessel is in Singapore, the surveyor must be MPA-licensed.

During delivery, the continuous drip sampler should be observed by a ship’s officer and the supplier’s representative throughout the delivery. If the sampler is not running correctly, bunkering should be stopped and restarted with a functioning sampler. Photographs or video of the sampling setup are recommended by both Gard and Skuld.

At completion, the BDN should be reviewed field by field before signing: IMO number matches the ship; sulphur content is consistent with the grade ordered and below the applicable limit; density is within the expected range for the grade; flashpoint field is completed (for deliveries after 1 May 2024); seal number on the sample matches the number to be noted on the BDN; and the supplier’s declaration is signed, not left blank.

If any field is disputed, sign under protest with a written letter of protest immediately. Do not delay the letter of protest: in some jurisdictions the right to protest lapses if not exercised promptly.

After bunkering, log the BDN number, delivery date, grade, quantity, sulphur content, and sample seal number in the Bunker Fuel Sample Log Book. File the BDN in the ship’s regulatory documentation. Store the sample correctly (see storage section). Cross-check the quantity with the ullage measurements taken by the ship’s crew as a verification step.

Limitations

Several aspects of the BDN framework have recognised limits that practitioners should understand.

Supplier self-declaration. The sulphur content on the BDN is the supplier’s own declared value, typically derived from the shore-side quality test of the cargo before loading onto the barge, not from a test of the exact parcel delivered to the ship. A parcel that meets 0.50% m/m in the shore tank can change character through contamination during barge operations. The MARPOL sample is the only way to verify what the ship actually received, and even that analysis takes days rather than seconds.

Sample representativeness. A continuous drip sampler collects a proportional sample from the flow at the manifold, but it cannot guarantee that the sample is chemically identical to the bulk parcel. Stratification in the barge tanks, temperature gradients in the piping, and short-circuiting of the sampler can all affect representativeness. The sampler must be calibrated and functioning correctly for the MARPOL sample to be legally defensible.

In-use sample timing. An in-use sample taken by a PSC officer shows what the engine is burning at that instant. If the ship has recently switched fuels and the service tank contains a blend of two parcels, the in-use sample reflects the blend, not either of the BDN-documented individual parcels. A ship that switched from non-compliant HFO to compliant VLSFO shortly before an ECA entry may have a compliant in-use reading even if the changeover was not complete.

Quantity measurement accuracy. Outside Singapore and other mass-flow-metering ports, BDN quantities are derived from tank gauging with measurement uncertainties that industry experience puts at up to 1% under good conditions. Claims below this threshold are difficult to sustain.

Electronic BDN jurisdiction variations. Not all flag states and port states have formally accepted electronic BDNs as of 2026. An electronic BDN compliant with MEPC.1/Circ.795/Rev.9 should be accepted in most major port state regimes, but ships trading to ports with older or stricter local requirements should verify local acceptance before relying solely on an e-BDN.

Flashpoint field compliance lag. MEPC.362(79) came into force 1 May 2024. Some suppliers outside major bunkering hubs were slow to update their BDN templates. A BDN issued after that date without a flashpoint field or statement is technically non-compliant, but enforcement practice on this new field is still developing across PSC regimes as of mid-2026.

See also

• MARPOL Annex VI: the full regulatory framework for air pollution prevention from ships
• MARPOL Annex VI Regulation 14: Sulphur Cap: the sulphur limits the BDN declaration must confirm
• IMO 2020 Sulphur Cap: the global 0.50% limit that makes the BDN sulphur field enforcement-critical
• Bunker Quality and ISO 8217: the fuel specification standard that operates alongside MARPOL compliance
• ISO 8217:2024: the current version of the marine fuel quality specification
• Fuel Switching Operations: the BDN-linked procedure for ECA entry and exit
• Port State Control: the inspection regime that uses the BDN as primary fuel evidence
• Exhaust Gas Cleaning System: the scrubber alternative that permits continued HFO use under Regulation 14
• Heavy Fuel Oil: the fuel grade subject to most BDN sulphur scrutiny
• Cylinder Oil Base Number and Fuel Sulphur: how BDN sulphur content drives cylinder lubrication decisions
• MARPOL Convention: the umbrella treaty of which Annex VI forms part
• Time Charter Party: commercial context for BDN obligations in charters