M3000-3.1.2

Responding to pollution incidents onboard and found at sea

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Vignette

It is 0340. You are anchored off Palma. Your Chief Engineer calls: a cracked fuel transfer pipe has discharged an unknown quantity of diesel into the bilge, and the oily water separator is now showing contaminated output. Before you are fully awake, you hear your Officer of the Watch report a visible sheen on the water to starboard. You are the Master. Two incidents, possibly connected, and the clock is already running.


Your immediate priorities as Master

You are not the engineer solving the mechanical problem. You are the person with legal accountability for what enters the sea, what gets recorded, and who gets told. Separate the two threads:

Source control first. Order the transfer stopped, isolate the damaged pipe, close overboard discharges. Nothing more goes over the side until you have assessed the situation.

Assess the sheen. A rainbow or silver sheen does not automatically mean an illegal discharge has occurred — it may be from the bilge incident, a passing vessel, or a natural source. Your job is to determine whether it originated from your vessel and to act on that assumption until proven otherwise.


Reporting obligations

MARPOL Annex I imposes a duty to report any discharge — actual or probable — of oil or oily mixture. The Balearic Islands are Spanish territorial waters; the competent authority is the relevant Spanish Maritime Rescue and Coordination Centre (MRCC) and port authority. Under the UK's reporting framework (and aligned to MARPOL Protocol I), a report must be made without delay if there is a harmful substance involved.

Report contents must include: vessel identity, position, date/time, type and quantity of substance if known, nature of the incident, and any action taken. Do not speculate on quantity if unknown — state it as unknown.

If operating under a flag state other than the UK, confirm local Port State reporting thresholds. As a UK-flagged or REG YC-compliant vessel, your SMS should specify the reporting chain clearly.


Oil Record Book entries

If your vessel is ≥400 GT, every discharge or escape must be entered in the ORB Part I. The entry must be made without delay, be accurate, and not be falsified — falsification of the ORB is a criminal offence under UK law. If nothing was discharged overboard, record that fact and the remedial action taken. The ORB entry is signed by the responsible officer, each page signed by the Master.


Pollution found at sea

You observe a large oil slick of unknown origin while on passage. You are not the source. Your obligations are:

  • Report the observation to the nearest MRCC with position, extent, appearance, and estimated drift.
  • Do not alter course into the slick unless conducting SAR.
  • Record time, position, weather, sea state, and your report in the Official Log.
  • Preserve any evidence if there is reason to believe a vessel was responsible.

Command responsibility

You cannot delegate the decision to discharge or the decision to report. Neither can you allow commercial pressure — an owner's anxiety about port delay — to influence whether a report is made. The penalties for unreported discharge, and the career and criminal consequences of falsifying records, are severe and fall on you personally.

Practice questions

oralcore

You're anchored in a foreign port and your Chief Engineer informs you that approximately 20 litres of diesel has escaped into the bilge and possibly overboard through a leaking sea cock. What do you do?

recallcore

Under MARPOL Annex I, what information must be included in an initial pollution report?

scenariocore

You are on passage and sight a large oil slick extending several miles. Your vessel is not the source. What are your obligations?

scenariostretch

Your owner contacts you by satellite phone shortly after your pollution report and asks you to 'keep it quiet' to avoid a port delay. How do you respond, and what is your legal position?

recallcore

What is the significance of the Oil Record Book entry when a pollution incident occurs on a vessel of 400 GT or above?

Independent preparatory study aligned to the MCA Master (Yachts less than 3000 GT) examination syllabus (updated June 2026). Not an MCA-approved course and confers no credit toward a Certificate of Competency.