So you’ve spilled oil in port: six mistakes that hurt more than the spill

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Nobody plans an oil spill during bunkering, and yet many investigations begin with the same sentence: “Bunkering was conducted as per procedure.” In port, especially a well-regulated one, the spill itself is only half the story. The other half is how the vessel behaves in the first few hours, because that is what authorities, insurers and investigators will replay long after the oil is gone. These are six mistakes that make an oil spill in port worse than it needs to be.

1. Delaying notification

Late reporting is the fastest way to turn a minor spill into a major problem. The expectation is immediate notification as soon as a spill, or a credible risk of pollution, is identified. In practice the first notification may come within minutes, but delays can stretch to tens of minutes or longer while the crew tries to confirm the source, estimate the quantity, stop the transfer or clean the deck. Other causes include uncertainty over who must report, fear of the consequences, a breakdown in communication between vessel and barge, and waiting for instructions from management.

The delay is usually counterproductive, because camera, AIS, terminal and witness records will establish the sequence anyway. A delay looks like hesitation, and hesitation looks like concealment. A small spill reported early is an incident. The same spill reported late becomes a question about credibility.

Reporting rules are local, so start with the coastal State and the port authority, because contact points and deadlines differ. MARPOL Annex I and the vessel’s approved SOPEP give the wider framework. In Singapore, for example, MPA Port Marine Circular No. 13 of 2025 requires bunkering-related incidents, including oil pollution, to be reported immediately to the Marine Safety Control Centre. No single port’s procedure is universal.

2. Treating the checklist as a formality

Checklists are there to prevent spills. After a spill they become evidence. Investigators look at when the bunkering checklist was signed, whether tank soundings were recorded properly, and whether pump rates and topping-off arrangements were agreed and followed. A half-completed checklist raises an uncomfortable question: if the paperwork was rushed, was the operation rushed too? In an investigation, neat paperwork does not protect you. Consistent paperwork does.

3. Fixating on the slick and ignoring the source

Everyone looks at the oil on the water. Authorities look at how it got there. Gard reports that overflow incidents account for the majority of the bunker spills it sees, pointing to high flow rates, incorrect line-up, inadequate tank monitoring and failure to act on high-level alarms. The UK P&I Club’s Risk Focus: Safe Bunker Operations likewise finds that most spills come from tank overflow, with hose or pipeline failure a minority. Common contributors include:

• incorrect or unmonitored pump rates;
• tank levels not monitored continuously, including tanks not being filled;
• over-reliance on alarms instead of manual checks;
• vent heads that are poorly maintained or modified.

Cleaning the sea surface is expected. Explaining why the system overflowed is what shapes the outcome. Containment shows response. Root cause analysis shows competence.

4. “Tidying up” the records too soon

After a spill there is a strong temptation to make the paperwork look better, and this is where things go wrong. Investigators commonly find overwritten log entries, a different hand or ink, unusual gaps, entries made out of sequence, rounded or repeated sounding figures, checklist timings that do not match alarms or communications, and records that are too neat for the circumstances.

They detect it by comparing the original records with VDR and AIS data, engine and alarm logs, electronic file metadata, bunker delivery documents, tank calculations, CCTV, photographs, phone and message records, and independent records from the barge, terminal or authority. A late correction should be transparent, dated and explained, not disguised as an original entry. If in doubt, record the facts and do not polish them.

5. Treating human factors and responsibility as an afterthought

Spills rarely happen because someone wanted to do the wrong thing. They happen because people were tired, rushed, distracted or misaligned. Commonly overlooked contributors include a change of watch during bunkering, pressure to finish because of the port schedule, and assumptions built on routine, such as “we have done this hundreds of times”.

Responsibility also becomes unclear most often at the vessel and barge interface: who controls the pumping rate, who orders a slowdown or shutdown, whether communications were understood, which valve line-up was correct, and whether the receiving vessel had enough capacity. The answer is the agreed bunkering plan and checklist, a pre-transfer conference, clearly recorded pumping and topping-up rates, emergency-stop arrangements, contemporaneous communications and tank records. Operational responsibility may be shared, but each side must perform and record its own checks. Human factors are not an excuse. They are usually the explanation.

6. Delaying the right external support

A crew may stop and contain the spill, but valuable time is lost if the port authority, P&I correspondent, pollution-response contractor and evidence-preservation support are not engaged promptly. Early support should not interfere with the emergency response. It should help coordinate it and preserve reliable records.

What to do in the first hour

1. Stop the transfer, raise the alarm and activate the agreed emergency shutdown.
2. Contain the oil using scuppers, save-alls, absorbents and SOPEP equipment, without washing oil overboard.
3. Notify the port authority and the required internal and external parties immediately, using the best information then available.
4. Preserve evidence and start a contemporaneous timeline, including photographs, soundings, alarms, communications and actions taken.
5. Keep one clear command and communication channel with the bunker barge, terminal and response authorities.

What the investigation looks at after an oil spill in port

Oil spills in port are not judged by how fast the cleanup was or how small the quantity was. They are judged by how quickly the spill was reported, how controlled the response was, and how aligned the crew, the office and the contractors appeared. In a highly regulated port, calm transparency beats frantic efficiency. The spill may last minutes, but the investigation lasts much longer, and it remembers everything.