ONDECK
Academy
OOW Oral Prep
Module 07 — OOW 3000 GT Oral Preparation
MARPOL
Marine pollution prevention — six annexes, special areas, SOPEP, Oil Record Book, Garbage Management Plan
MARPOL 73/78 — the International Convention for the Prevention of Pollution from Ships. Entered into force 1983. Comprises six annexes each addressing a different type of pollution. Applies to all vessels flagged to signatory states.
The Six Annexes — Know All of Them
| Annex | Subject | Key requirement | Status |
|---|---|---|---|
| Annex I | Oil | Prohibits discharge of oil or oily mixtures except in permitted circumstances (15 ppm rule outside special areas, with OWS and ORB). No discharge in special areas | Mandatory |
| Annex II | Noxious Liquid Substances (NLS) | Regulates discharge of chemicals carried in bulk — tankers primarily. Residues must be discharged to port reception facilities | Mandatory |
| Annex III | Harmful Substances in Packaged Form | Covers marking, labelling, packaging, documentation, stowage and quantity limits for harmful substances carried in packaged form | Mandatory |
| Annex IV | Sewage | Prohibits discharge of untreated sewage within specified distances from land. Requires ISPP Certificate for vessels over 400 GT | Mandatory |
| Annex V | Garbage | Prohibits disposal of all plastics at sea. Regulates disposal of food waste and other garbage by distance from land. Garbage Management Plan and Garbage Record Book required for vessels 100 GT+ | Mandatory |
| Annex VI | Air Pollution | Limits sulphur content of fuel oil — 0.5% globally (2020), 0.1% in ECAs. Controls NOx emissions from diesel engines. Prohibits deliberate emissions of ozone-depleting substances | Mandatory |
Annex I — Oil Pollution: What the Examiner Focuses On
| Requirement | Detail |
|---|---|
| 15 ppm Rule | Machinery space bilge water may only be discharged at sea if: oil content is less than 15 ppm, the vessel is underway, the Oily Water Separator (OWS) is in operation, and the Oil Discharge Monitoring Equipment (ODME) is functioning |
| Special Areas — no discharge | Mediterranean Sea, Baltic Sea, Black Sea, Red Sea, Gulfs Area, Gulf of Aden, Antarctic Area, NW European Waters — no operational discharge of oily water even at 15 ppm |
| Oil Record Book (ORB) | All operations involving oil must be recorded — bunkering, transfers, bilge discharges, use of OWS. PSC will inspect ORB. Falsification is a criminal offence. Must be retained for 3 years |
| SOPEP | Shipboard Oil Pollution Emergency Plan — required on all vessels over 400 GT. Sets out procedures for reporting and responding to an oil pollution incident. Must be approved by the flag state |
MAGIC PIPE: Bypassing the OWS to discharge oily bilge water directly overboard is a criminal offence. Officers have been imprisoned for falsifying the ORB. The OOW who allows or ignores this is personally liable.
Annex V — Garbage: Superyacht Relevance
| Garbage type | Outside special areas | Special areas |
|---|---|---|
| Plastics (all) | Prohibited — no discharge anywhere at sea | Prohibited |
| Food waste | 12nm+ from nearest land (comminuted/ground: 3nm+) | 12nm+ (some special areas: not permitted at all) |
| Cargo residues | 12nm+ if not harmful to marine environment | Prohibited |
| Cleaning agents / additives | Permitted if not harmful | Prohibited if harmful to marine environment |
| All other garbage | Prohibited | Prohibited |
Garbage Management Plan
- Required for vessels 100 GT and over
- Procedures for collecting, storing, processing, and disposing of garbage
- Designated person responsible for the plan
- Written in working language of the crew
Garbage Record Book
- Required for vessels 400 GT and over
- All discharges to sea or port reception facilities recorded
- Accidental loss also recorded
- Retained for 2 years — available for PSC inspection
Annex VI — Emission Control Areas (ECAs)
| Area | SOx limit | Applicable since |
|---|---|---|
| Global (outside ECAs) | 0.50% sulphur | January 2020 |
| ECAs (SOx) | 0.10% sulphur | January 2015 |
| North Sea / Baltic Sea ECA | 0.10% | — |
| North American ECA (200nm from coast) | 0.10% | — |
| US Caribbean Sea ECA | 0.10% | — |
| Mediterranean Sea ECA (from 2025) | 0.10% | May 2025 |
FUEL CHANGEOVER: When entering an ECA, the vessel must switch to compliant low-sulphur fuel. The changeover must be logged — record the time, position, and tank quantities before and after. Allow sufficient time for fuel system changeover before entering the ECA boundary.
Reporting a Pollution Incident
Any actual or probable discharge of oil or other harmful substances must be reported immediately to the nearest coastal state and to the flag state. Failure to report is itself an offence.
The report must include:
- Name and flag of vessel
- Position, course, speed
- Time and date of incident
- Type of incident
- Type and quantity of substance involved
- Actions taken or intended
- Assistance required
- Weather conditions
Annex I In Depth — The Oil Record Book Is the Case File
Annex I prosecutions are rarely won on the discharge itself — they are won on the Oil Record Book. Every transfer, every bunkering, every discharge ashore or overboard, every sludge landing is entered with date, position, quantities and signatures, and the entries must reconcile with the physical tank soundings. Surveyors and Port State inspectors read the ORB against the sounding log, the bunker delivery notes and the reception facility receipts — an ORB that doesn't add up reads as falsification, and falsification ("magic pipe" cases) turns a fine into a criminal conviction that ends careers.
| Item | The working standard |
|---|---|
| 15 ppm equipment | Oily water separator/filtering equipment approved and maintained; in Special Areas (the Med) the alarm and automatic stopping device must be functioning |
| Discharge conditions | Vessel en route; ≤15 ppm through approved equipment; not in a prohibited area; recorded in the ORB |
| Sludge | Retained in the sludge tank; landed ashore to reception facilities; receipts kept with the ORB |
| Bunkering | Pre-transfer checklist: comms and emergency stop agreed, scuppers plugged, drip trays and absorbents ready, tanks gauged, watch posted — Bravo flag/light shown per port rules |
The default that keeps you employed: when any link in the chain is doubtful — equipment unproven, alarm defective, position uncertain — the bilge water stays aboard and lands ashore as slops, with the receipt stapled into the record. Nobody has ever been prosecuted for landing slops ashore.
Annex IV — Sewage (The Yacht Blind Spot)
Sewage rules bite yachts hard because guest numbers drive tank cycles. The discharge ladder for a vessel to which Annex IV applies:
| Condition | Where permitted |
|---|---|
| Through an approved sewage treatment plant (certified, working) | Effluent may be discharged subject to the plant's certification — no visible floating solids, no discolouration |
| Comminuted and disinfected sewage | More than 3 nm from the nearest land, en route |
| Untreated sewage from holding tanks | More than 12 nm from the nearest land, en route at ≥4 knots, discharged at a moderate rate — never in port, never at anchor inshore |
What actually happens on charter: the black tank fills in the bay. The compliant answers are the treatment plant (maintained — a dead plant means holding-tank rules apply), a pump-out ashore, or a run offshore. Discharging an untreated tank at anchor in a Balearic cala is an offence, an anchorage-wide embarrassment, and increasingly, a fined and photographed one. Local rules can be stricter than MARPOL — some areas prohibit all discharge; check the almanac and local regulations.
Annex VI — Air: The One That Changed Recently
Annex VI limits sulphur oxides, nitrogen oxides and other emissions — and it moved recently enough that currency itself is examinable:
| Requirement | Standard |
|---|---|
| Sulphur limit — global | 0.50% m/m fuel sulphur content (since 2020) |
| Sulphur limit — Emission Control Areas | 0.10% m/m. ECAs include the Baltic, North Sea, North American and US Caribbean areas — and the Mediterranean became a SOx ECA with the 0.10% limit effective from 1 May 2025. A Med-based yacht lives inside it all season |
| Evidence | Bunker Delivery Notes retained (3 years) with fuel samples; the BDN sulphur figure is the Port State's first check |
| NOx | Engine certification by tier and build date (EIAPP certificates); relevant at survey rather than on watch |
| Incinerators & ODS | Shipboard incineration only in approved incinerators and never of prohibited materials; ozone-depleting substances (old refrigerants) controlled — deliberate release prohibited, records for rechargeable systems |
Say the date: "the Mediterranean SOx ECA came into effect on 1 May 2025 — we bunker 0.10% sulphur fuel and keep the BDNs" is a sentence that tells an examiner your knowledge is current, not copied from an old set of notes.
Special Areas — Where the Rules Tighten
Special Areas are sea areas where, for oceanographic and traffic reasons, the discharge standards tighten. The ones a yacht OOW actually operates in: the Mediterranean (Annex I oil, Annex V garbage — and now an Annex VI SOx ECA), the Baltic (I, IV, V, VI), the North Sea (V, VI), the Wider Caribbean (V). Operationally the lesson is simple: a Med-based yacht should run to Special Area standards as her default — everything retained, everything landed, everything receipted — because she is never outside one for long.
Pollution Reporting — Who You Call and When
Any actual or probable discharge of oil or harmful substances triggers a reporting duty (MARPOL Protocol I): report without delay to the nearest coastal state — the fastest channel available, usually coast radio/VTS or the MRCC — plus flag state and the company/DPA per the SOPEP contact list, which is exactly what that appendix of the SOPEP is for. Report facts: position, time, type and estimated quantity, cause, actions taken, assistance needed. The pattern repeats from every other emergency topic: prompt honest reporting is consistently the cheapest line in the whole affair, and failure to report is a separate offence that outlives the spill itself.
Oral Exam Practice Questions
Question 1
Name the six MARPOL annexes.
Annex I — Oil. Annex II — Noxious Liquid Substances in Bulk. Annex III — Harmful Substances in Packaged Form. Annex IV — Sewage. Annex V — Garbage. Annex VI — Air Pollution. All six are mandatory for signatory states.
Question 2
Under what conditions can you discharge bilge water under Annex I?
The vessel must be underway, outside a special area, and the oil content must be less than 15 parts per million. The Oily Water Separator must be operational and the Oil Discharge Monitoring Equipment must be functioning and recording. The discharge must be recorded in the Oil Record Book. In special areas — including the Mediterranean — machinery-space bilge water may still be discharged en route, but only processed to 15 ppm or less through oil filtering equipment fitted with a 15 ppm alarm and automatic stopping device; the outright prohibitions apply to cargo-area discharges from tankers. In practice many yachts run a zero-discharge policy in the Med and land bilge water ashore.
Question 3
What is the SOPEP?
The Shipboard Oil Pollution Emergency Plan. Required on all vessels of 400 GT and over under MARPOL Annex I. It sets out the procedures the crew must follow in the event of an oil pollution incident — including who to notify, what actions to take to stop or minimise the discharge, and reporting requirements. It must be approved by the flag state administration.
Question 4
What is the sulphur limit inside an ECA and when do you need to change fuel?
Inside an Emission Control Area the sulphur content of fuel must not exceed 0.10%. Outside ECAs the global limit is 0.50% (since January 2020). When transiting into an ECA I must switch to compliant low-sulphur fuel before crossing the ECA boundary. The changeover must be logged — record the time, position, and tank quantities. The North Sea, Baltic, North American coast, US Caribbean, and Mediterranean Sea (from May 2025) are all ECAs.