Environmental Compliance

Every serious environmental enforcement action against a ship starts the same way: an inspector opens the Oil Record Book, the Garbage Record Book or the Ballast Water Record Book and checks whether what is written matches what the ship's own instruments, tank soundings and engine logs say happened. It is rare for a prosecution to turn on the discharge itself — a competent crew operating serviceable equipment is usually within the limits. What gets a master or chief engineer into court is the record: an entry made a day late, a quantity that does not reconcile with a flowmeter reading, a missing signature, or a tank-to-tank transfer that was never logged. In practice the record book is treated as close to a sworn statement — it is the primary evidence a flag or port state has, because nobody re-measures yesterday's discharge after the fact.

This is why the discipline around record-keeping matters as much as the operation itself. Each entry should be made by the officer who carried out or supervised the operation, at the time it happened or as soon as practicable afterwards, and countersigned by the master at appropriate intervals. Writing a week's entries from memory on a Sunday evening is not a shortcut — it is, in substance, a false entry, because the dates, times and quantities it records will not line up with the ship's own automated data, even where the underlying operations were entirely legitimate.

Annex I does not give the machinery space bilge system a single number to hit; it gives a set of conditions that all have to be true at the same moment. The ship must be en route — under way and proceeding on a passage, not stopped, anchored or manoeuvring in port. The 15 ppm oil content meter must be running, with its output at or below the limit continuously through the discharge, not just at the instant someone glances at a gauge. And the system must have a functioning automatic stopping device that shuts the overboard valve the moment the reading exceeds the limit, so compliance does not depend on an operator noticing in time.

The reason it is built this way is that the risk being managed is not a fixed quantity of oil, it is where that oil ends up. A discharge testing at 9 ppm is chemically no different whether the ship is at anchor or steaming past — but at anchor or alongside, any oil discharged concentrates in confined, often shallow water near other vessels, moorings and a coastline, instead of being dispersed by way through open sea. "En route" is therefore doing environmental work, not administrative work: it is the condition that ensures whatever residual oil passes the monitor gets diluted rather than pooled. A crew that discharges a compliant reading while at anchor because the bilge well is filling has solved an operational problem by creating a discharge offence.

Annex IV treats sewage as something to be processed, not simply diluted. A ship with an approved sewage treatment plant may discharge treated effluent essentially without a distance restriction, because the plant has already done the environmental work. Without one, raw sewage may only be discharged once it has been comminuted and disinfected, and even then only beyond 3 nautical miles from the nearest land; untreated sewage from a holding tank requires a considerably greater distance, and the ship must be proceeding at a moderate speed so the effluent disperses rather than trailing in a slick astern. The common thread is that distance from land substitutes for treatment, not an alternative to it — the further out you are, the less processing the rule demands, but retention and proper eventual disposal remain the fallback throughout.

Annex V is written the other way round: the default position for garbage is that it stays on board. Rather than listing what may be discharged, the annex is best read as a general prohibition with a small number of narrow, closely defined exceptions, chiefly around food waste, and even those exceptions still require minimum distances from land that grow larger the closer the ship is to a designated special area. Everything else — plastics above all, but also most operational and cargo-associated waste — is retained and landed ashore. The Garbage Record Book logs each disposal or landing by category and quantity, and placards describing the discharge restrictions must be posted where the crew will actually see them, because the rule only works if every rating handling waste understands it, not just the officer signing the log.

Ballast water keeps a ship trimmed, stable and structurally sound, but it also moves organisms between ecosystems that have no natural way of reaching each other otherwise. The Ballast Water Management Convention deals with this in two distinct ways, and a candidate needs to be able to tell them apart. D-1 is an exchange standard: ballast taken up in one region is replaced with open-ocean water, either by flow-through pumping of at least three times the tank's volume or by achieving at least 95% volumetric exchange, carried out well clear of land and in deep water so the organisms released are ones already adapted to the open ocean rather than to a coastal or port environment. D-1 was always meant as a transitional measure — it depends on geography and voyage length allowing the ship to reach suitable water before it needs to ballast down or discharge.

D-2 is a performance standard: it does not prescribe how the water is treated, only what comes out the other end. The ship carries a type-approved treatment system — typically filtration followed by disinfection such as UV or electrochlorination — and the system's approval certifies that, operated correctly, it reduces viable organisms in the discharged water below the limits the standard sets for different size classes. Because D-2 is a performance outcome rather than a procedure, a system that is not operating correctly does not create a grey area — its output either meets the standard or it does not, and the ship's fallback if it fails follows the same principle as everywhere else in this chapter: record the failure, follow the contingency measures in the ship's own Ballast Water Management Plan, and report it, rather than quietly discharging anyway or forcing an exchange the voyage was never long enough to support.

Annex VI regulates two different things under one heading, and answers that blur them lose marks. Sulphur and NOx are pollutant limits on the fuel and the engine: fuel oil sulphur content is capped at 0.50% by mass globally, and at 0.10% inside an Emission Control Area, unless the ship instead uses an approved equivalent means — most commonly an exhaust gas cleaning system, a scrubber, that removes sulphur oxides after combustion rather than avoiding them before it. NOx is controlled at the engine itself, in tiers set by the ship's keel-laying date rather than by where it trades: a Tier III engine has to be fitted to operate in a NOx Emission Control Area, and the step up in stringency between tiers reflects what engine technology of each era could achieve, not a change in the underlying pollutant being limited.

EEXI and CII are a different pair again, and the distinction examiners like to test is technical-versus-operational. The EEXI is a design index: it is calculated once, from the ship's engine power, deadweight and speed, verified at a single survey, and it does not change unless the ship itself is physically modified — new engine, power limitation, energy-saving device. The CII is recalculated every single year from what actually happened: fuel consumed and distance sailed give an attained carbon intensity, compared against a reducing annual threshold and converted into a letter rating, A through E. A ship can have an excellent EEXI on paper and still earn a poor CII rating through inefficient operation, and it is the CII, not the EEXI, that drives consequences — three consecutive years of a D rating, or a single E rating, requires a corrective action plan to be developed and worked into the ship's SEEMP.

The two scenarios below are the kind of judgement question this paper favours: a plausible operational pressure pushing toward a shortcut, and a decision that has to be defended out loud, not just calculated.

Worked example 1

Bilge discharge criteria — a compliant reading is not the same as a compliant discharge

You are officer of the watch on a 32,000 GT bulk carrier at anchor, waiting for a pilot to bring you alongside. The chief engineer reports the bilge holding well in the engine room is getting full and asks permission to run the oily water separator overboard rather than to the slop tank, since the 15 ppm monitor is reading well inside the limit. The main engine is stopped and will not be ready to manoeuvre until the pilot boards.

Given

- Vessel at anchor, main engine stopped; pilot expected in 6 hours - Oily water separator running; 15 ppm monitor reading 9 ppm; automatic stopping device in service - Bilge holding well capacity 2.4 m³, currently 85% full - Estimated bilge inflow to the well: 0.3 m³ per day

1. Check every discharge condition separately before looking at the bilge well.

   A 9 ppm reading only satisfies the concentration condition. Annex I sets that alongside three others that all have to hold at the same moment: the ship must be en route, the monitor must be running continuously, and the automatic stopping device must be functional. At anchor, with the main engine stopped, the ship is not en route — it makes no difference that the monitor reads well under 15 ppm.

2. Work out whether the well can simply wait.

   Available capacity=2.4 × (1 − 0.85) =2.4 × 0.15 =0.36 m³ Time to fill=0.36 ÷ 0.3 =1.2 days =28.8 h

   Since if it is about to overflow the pressure to discharge now is real rather than just convenient.

3. Compare that margin against the time before the ship is actually under way again.

   The pilot, and with it the chance to discharge en route, is 6 hours off — far inside the 28.8 hours of spare capacity the well still has. There is no overflow emergency here, so nothing forces an overboard discharge before the en route condition can genuinely be met.

AnswerDo not discharge overboard now. Keep the separator running to the holding or slop tank, resume overboard discharge once the ship is under way and all four conditions are met, and note the reason for retention in the Oil Record Book.

The trap: a good ppm reading feels like permission to discharge; it is only one of four conditions, and "en route" is not satisfied by an engine that could be started soon — the ship has to actually be under way.

Worked example 2

Ballast treatment failure on a voyage too short for exchange

You are second engineer on a short-sea ferry making a 4-hour coastal crossing that never takes the vessel more than 190 nautical miles — in practice only a few miles — from the nearest land. Before departure the ship needs to ballast down. Shortly after ballasting begins, the UV lamp in the ballast water treatment system trips on a fault and will not reset. The chief officer, keen not to delay sailing, asks whether you can simply keep pumping the tank up raw and "exchange it properly next trip."

Given

- Coastal voyage; vessel never more than 190 nautical miles from the nearest land - Ballast tank capacity: 1000 m³ - Treatment system rated flow: 250 m³/h - System operated for 0.8 h (48 min) before the UV unit failed and would not reset

1. Check whether D-1 exchange is even available as a fallback.

   D-1 exchange has to be carried out well clear of land and in deep water — broadly, at least 200 nautical miles from the nearest land. This voyage never reaches anywhere near that offshore, so D-1 is not achievable on this passage, on this trip or the next — "exchange it properly next trip" does not solve anything, because the geography does not change.

2. Establish how much of the tank was actually treated before the fault.

   Volume treated=250 × 0.8 =200 m³ Volume untreated=1000 − 200 =800 m³

   So the failure can be reported accurately rather than approximately.

3. With D-2 unavailable (system failed) and D-1 unavailable (geography).

   The decision is not a choice between two compliant methods — it is about managing and documenting a genuine equipment failure under the ship's own Ballast Water Management Plan, which sets out contingency measures for exactly this situation, such as minimising further untreated uptake or treating on discharge if the system can be restored in time.

AnswerStop ballasting or minimise the untreated volume taken up, following the ship's Ballast Water Management Plan; do not top the tank up untreated and do not attempt a D-1 exchange on this voyage. Record the failure and both volumes — 200 m³ treated, 800 m³ untreated — in the Ballast Water Record Book, and notify the next port's authorities of the deficiency before arrival.

The trap: treating this as paperwork to sort out next trip. A mid-operation treatment failure on a voyage too short for exchange has to be recorded and reported as a deficiency now, not quietly absorbed into a normal-looking ballast log.