MARPOL Annex I runs to nearly 40 substantive regulations across seven chapters, but the whole structure hangs on its first two. Regulation 1 is the definitions article. Regulation 2 is the application article. Neither imposes a single equipment standard or discharge limit on its own. Together they decide which standard and which limit apply to a given hull, in a given trade, on a given day. A surveyor who misreads Regulation 1.5 puts a ship in the wrong certificate class. A superintendent who misreads Regulation 2 applies a tanker construction rule to a dry-cargo ship’s settling tank, or fails to apply it where the rule actually bites.
This article covers the formal text of Regulation 1 and Regulation 2 of the revised Annex I, the version adopted by IMO resolution MEPC.117(52) on 15 October 2004 and in force from 1 January 2007. The broader history, the discharge limits, and the construction standards live in the MARPOL Annex I overview and in the MARPOL Convention article. Here the subject is narrower and more exact: the words themselves, and the legal scope they switch on.
A note on Chapter 1 and the regulation numbering
Chapter 1 of Annex I, titled “General,” holds Regulations 1 through 5: Definitions (Reg 1), Application (Reg 2), Exemptions and waivers (Reg 3), Exceptions (Reg 4), and Equivalents (Reg 5). The brief for this article asked us to confirm that Regulation 1 is “Definitions” and Regulation 2 is “Application.” Both titles are confirmed against the consolidated text. The defined terms in Regulation 1 are numbered as sub-paragraphs (1.1 Oil, 1.2 Crude oil, 1.3 Oily mixture, and so on through 1.28), and that numbering is load-bearing: later regulations cite the definitions by number, so Regulation 34 reads “delivered after 31 December 1979, as defined in regulation 1.28.2” rather than spelling out the test again.
One correction worth flagging at the top. The older Annex I used the paired terms “new ship” and “existing ship,” hinged on whether the ship was built before or after the Annex entered force. The revised Annex I retired that pair. The current text instead defines delivery-date classes in Regulation 1.28, the most general of which are “ship delivered on or before 31 December 1979” (Reg 1.28.1) and “ship delivered after 31 December 1979” (Reg 1.28.2). Practitioners still say “new” and “existing” in conversation, and the underlying concept survives, but the formal definitions no longer use those words. Where this article uses “new” or “existing,” read it as shorthand for the delivery-date class, not as a quotation of the Annex.
Regulation 1: what “oil” means and why the boundary matters
The Annex regulates pollution by oil, so the first job of Regulation 1 is to say what oil is. Regulation 1.1 defines oil as “petroleum in any form including crude oil, fuel oil, sludge, oil refuse and refined products,” with one carve-out: petrochemicals subject to Annex II are excluded. The definition then points to appendix I to the Annex, which lists the substances treated as oil. The petrochemical exclusion is the part that bites. A chemical tanker carrying a product on the Annex II noxious-liquid list is governed by Annex II for that cargo, not Annex I, even though the substance is a hydrocarbon. The boundary between the two Annexes runs through this sentence.
Regulation 1.2 narrows in on crude oil: “any liquid hydrocarbon mixture occurring naturally in the earth whether or not treated to render it suitable for transportation.” It expressly includes crude from which distillate fractions have been removed and crude to which fractions have been added. That breadth keeps topped or spiked crudes inside the crude-oil class, which matters because the crude oil washing (COW) requirements in later regulations attach to crude-oil service, not to clean products.
Oily mixture in Regulation 1.3 is deliberately wide: “a mixture with any oil content.” There is no threshold. A mixture is oily if it contains any oil at all. The discharge controls in Regulation 15 for machinery-space bilge water and in Regulation 34 for the cargo area both operate on this term, so the question is never “is there enough oil to count,” only “how much, and discharged how.” The 15 ppm machinery-space limit and the cargo-area limits do the quantitative work; the definition just establishes that any trace puts the effluent in scope.
Oil fuel in Regulation 1.4 means “any oil used as fuel in connection with the propulsion and auxiliary machinery of the ship in which such oil is carried.” This is the bunkers definition. It keeps a ship’s own fuel oil inside Annex I regardless of the ship type, which is why a bulk carrier’s fuel-oil system and bunker tanks fall under Annex I even though the ship carries no oil cargo. The term also feeds the segregated-ballast definition below: ballast water is only segregated if it is completely separated from both the cargo oil and the oil fuel system.
The tanker family: five definitions that decide the certificate
Five linked definitions sort ships into the tanker classes that drive Annex I’s heaviest construction and discharge rules. They have to be read together.
Oil tanker (Regulation 1.5) is the parent term: “a ship constructed or adapted primarily to carry oil in bulk in its cargo spaces.” The definition then sweeps in three more ship types when they carry oil in bulk: combination carriers, any NLS tanker as defined in Annex II, and any gas carrier as defined in regulation 3.20 of chapter II-1 of SOLAS 74 as amended. The “constructed or adapted primarily” wording is what catches a converted hull. A ship adapted to carry oil in bulk becomes an oil tanker even if it was built for another trade, which is the route by which a converted FSU can land inside the tanker definition.
Crude oil tanker (Regulation 1.6) is “an oil tanker engaged in the trade of carrying crude oil,” and product carrier (Regulation 1.7) is “an oil tanker engaged in the trade of carrying oil other than crude oil.” Note that both definitions turn on the trade, not on the steel. The same hull can move between the two classes as its trade changes, which matters because crude oil washing obligations attach to crude service. A product carrier that switches to crude trade picks up the crude-service obligations with the cargo.
Combination carrier (Regulation 1.8) is “a ship designed to carry either oil or solid cargoes in bulk.” The classic example is the ore/bulk/oil (OBO) carrier and the oil/ore carrier. Because Regulation 1.5 folds combination carriers into the oil-tanker definition, an OBO carrying an oil cargo is an oil tanker for Annex I purposes and carries the full tanker discharge regime in the cargo area, including the Regulation 34 controls.
These five terms are the reason the International Oil Pollution Prevention Certificate comes in two forms. The IOPP Certificate has a Form A supplement for ships other than oil tankers and a Form B supplement for oil tankers, and the line between them runs straight through Regulation 1.5. Misclassify the ship and the wrong supplement, with the wrong survey items, follows.
The tank vocabulary: tank, wing, centre, and slop
Annex I’s construction and discharge rules talk constantly about tanks, and Regulation 1 fixes four tank terms so those rules read precisely. Tank (Regulation 1.13) is “an enclosed space which is formed by the permanent structure of a ship and which is designed for the carriage of liquid in bulk.” The “permanent structure” wording excludes portable or independent tanks set into a hold; a deep tank built into the ship is a tank, a drop-in container is not.
The next two terms locate a tank in the cross-section, which matters because the outflow and protective-location rules treat side and centerline tanks differently. Wing tank (Regulation 1.14) is “any tank adjacent to the side shell plating,” and centre tank (Regulation 1.15) is “any tank inboard of a longitudinal bulkhead.” A wing tank is exposed to side damage in a collision; a centre tank sits protected behind the wing tanks. The accidental-outflow and protective-location provisions place segregated ballast in the wing positions precisely so a struck wing tank floods with ballast rather than spilling cargo, and that arrangement only works because the definitions draw the wing-versus-centre line at the longitudinal bulkhead.
Slop tank (Regulation 1.16) is “a tank specifically designated for the collection of tank drainings, tank washings and other oily mixtures.” The slop tank is where the load-on-top method concentrates oily residues so that water can be decanted from beneath the oil layer and the oil retained on board. The slop-tank arrangement is one of the conditions a tanker must satisfy under Regulation 34 before it may discharge cargo-area effluent at sea, which is why the definition sits up front in Regulation 1 rather than inside the discharge rule. Without a designated slop tank, the load-on-top discharge right does not exist.
The delivery-date classes: Regulation 1.28 and the “constructed” test
Annex I phases its construction standards in by build date. A double-hull requirement, an outflow limit, a segregated-ballast obligation: each one applies from a cut-off date, and a ship’s obligations depend on which side of that date it falls. Regulation 1.28 holds the machinery that decides the side.
The two broadest classes are ship delivered on or before 31 December 1979 (Regulation 1.28.1) and ship delivered after 31 December 1979 (Regulation 1.28.2). Each is defined by a four-limb test, and a ship qualifies if it meets any limb. For the “after 31 December 1979” class the limbs are: a building contract placed after 31 December 1975; or, absent a contract, a keel laid or a similar stage of construction reached after 30 June 1976; or delivery after 31 December 1979; or a major conversion contracted, begun, or completed after the matching dates. The “on or before” class mirrors it with the dates reversed.
The structure repeats the “construction” test that runs through IMO instruments generally: the date a ship is “constructed” is the date its keel is laid or it is at a similar stage of construction. The “similar stage of construction” wording catches modern modular builds where no single keel-laying event happens, and it is what a surveyor checks when a building contract is silent or absent. The three triggers, contract, keel, delivery, are tested in turn, and the earliest one that the ship meets fixes the class.
Two more delivery classes in Regulation 1.28 are tanker-specific and date-shifted: “oil tanker delivered on or before 1 June 1982” (Reg 1.28.3) and “oil tanker delivered after 1 June 1982” (Reg 1.28.4), each built on the same four-limb pattern with the dates moved to suit the segregated-ballast and outflow phase-ins. A fifth class, “oil tanker delivered on or after 6 July 1996” (Reg 1.28.6), keys the double-hull phase-in. The exact date depends on which obligation is in play, which is why later regulations always cite the specific sub-paragraph rather than a generic “new tanker.”
Major conversion (Regulation 1.9) sits alongside the delivery classes because a conversion can reset a ship’s date class. The definition covers a conversion that substantially alters dimensions or carrying capacity, changes the ship type, is intended to prolong the ship’s life, or otherwise alters the ship so that, if it were a new ship, it would become subject to provisions that did not apply to it as an existing ship. The last limb is the operative one: a conversion that would have triggered new-build rules on a fresh hull pulls the converted ship up to the corresponding standard. The definition carves out two conversions so they are not treated as major: converting a pre-1 June 1982 tanker of 20,000 tonnes deadweight and above to meet Regulation 18 segregated-ballast requirements, and converting a pre-6 July 1996 tanker to meet the Regulation 19 double-hull requirements. Without those carve-outs, a ship retrofitted to comply would have triggered the very new-build rules the retrofit was meant to satisfy.
“Nearest land” and the Great Barrier Reef line
Discharge of oily mixtures in the cargo area is allowed only at a distance from land. The measuring point is the nearest land, and Regulation 1.10 defines it with one geographic exception that every superintendent in the Australian trade has to know.
The general rule: “the term from the nearest land means from the baseline from which the territorial sea of the territory in question is established in accordance with international law.” So the distance is measured from the territorial-sea baseline, not from the visible coastline. Where a state draws straight baselines across a bay or around an island fringe, the baseline sits seaward of the shore, and the distance to “nearest land” is measured from there.
The exception is the Great Barrier Reef. Off the north-eastern coast of Australia, “from the nearest land” means from a coordinate line, not from the baseline. The Annex lists the line as a sequence of latitude and longitude points running from latitude 11 deg 00’ S, longitude 142 deg 08’ E down to latitude 24 deg 42’ S, longitude 153 deg 15’ E, tracing a line well seaward of the reef. This is the only place in Annex I where a fixed coordinate line replaces the territorial-sea baseline as the reference for “nearest land.” The reason is the reef itself: the baseline runs close inshore, but the coral lies far offshore, so measuring from the baseline would let a ship discharge close to vulnerable reef. The coordinate line pushes the discharge point seaward of the whole reef structure.
Why does this definition decide an operative rule? Because Regulation 34 permits cargo-area discharge only when, among other conditions, “the tanker is more than 50 nautical miles from the nearest land.” The 50-nautical-mile gate is meaningless without the “nearest land” definition. Inside the Great Barrier Reef exception, the 50 nm is measured from the coordinate line, which effectively bars cargo-area discharge across a much wider band than the bare distance suggests. One definition, read into one discharge condition, redraws the discharge map for an entire region.
“Special area” and the eight named areas
Special area (Regulation 1.11) is “a sea area where for recognized technical reasons in relation to its oceanographical and ecological condition and to the particular character of its traffic the adoption of special mandatory methods for the prevention of sea pollution by oil is required.” That is the test for designation. The Annex then names the special areas and gives each a precise boundary.
For Annex I the special areas are the Mediterranean Sea, the Baltic Sea, the Black Sea, the Red Sea, the “Gulfs area,” the Gulf of Aden, the Antarctic area (south of latitude 60 deg S), the North West European waters, the Oman area of the Arabian Sea, and the Southern South African waters. Each definition carries coordinates: the Mediterranean is bounded from the Black Sea by the 41 deg N parallel and to the west by the meridian of 005 deg 36’ W at Gibraltar; the Antarctic area is simply everything south of latitude 60 deg S. The boundaries are part of the definition, not a separate schedule, which is why a master needs the coordinates, not just the area name, to know when the ship has crossed into a special-area regime.
The reason the definition sits in Regulation 1 rather than buried in the discharge rules is that “special area” is referenced across multiple operative regulations. Inside a special area the cargo-area discharge of Regulation 34 is prohibited outright for most cases, and the machinery-space limits of Regulation 15 tighten. The full mechanics of each area, including the entry-into-effect dates that lag the formal designation, are covered in the MARPOL Annex I special areas article. Here the point is structural: the definition fixes the geography once, and every operative rule that says “in a special area” inherits it.
“Instantaneous rate of discharge of oil content”: a definition that is a formula
Most of Regulation 1 defines nouns. Regulation 1.12 defines a rate, and it does so as an equation. The instantaneous rate of discharge of oil content “means the rate of discharge of oil in litres per hour at any instant divided by the speed of the ship in knots at the same instant.” Written out:
where is the instantaneous rate of discharge of oil content in liters per nautical mile, is the rate of discharge of oil in liters per hour at the instant, and is the ship’s speed in knots at the same instant. The units resolve cleanly: liters per hour divided by nautical miles per hour gives liters per nautical mile, because a knot is one nautical mile per hour.
This definition is the quantity that Regulation 34 caps. One of the conditions for permitted cargo-area discharge is that “the instantaneous rate of discharge of oil content does not exceed 30 litres per nautical mile.” The oil discharge monitoring and control system (ODMCS) on a tanker computes exactly this rate in real time, taking the measured oil-in-water content and the pump rate to get liters per hour, then dividing by the ship’s speed from the speed log. If the result climbs above 30 L/nm, the system must stop the discharge. The definition is therefore not academic; it is the formula the ODMCS implements and the figure the Oil Record Book records. Tying the rate to speed is deliberate: a faster ship spreads the same hourly oil discharge over more sea, so the per-mile concentration falls, and the Annex measures the environmental load per mile of track rather than per hour of pumping.
Clean ballast, segregated ballast, and the 15 ppm test
Two ballast definitions matter because Annex I treats ballast water that has touched oil differently from ballast water that has not. Both sit in Regulation 1, and one of them carries a numeric test inside the definition itself.
Clean ballast (Regulation 1.17) is ballast in a tank which, since oil was last carried in it, has been so cleaned that the effluent, if discharged from a stationary ship into clean calm water on a clear day, “would not produce visible traces of oil on the surface of the water or on adjoining shorelines or cause a sludge or emulsion to be deposited.” That is the visual test. The definition then adds an instrument test: if the ballast is discharged through an approved oil discharge monitoring and control system, evidence that the oil content of the effluent did not exceed 15 parts per million “shall be determinative that the ballast was clean, notwithstanding the presence of visible traces.” So the 15 ppm reading overrides the eye. A sheen that would fail the visual test does not make the ballast dirty if the ODMCS confirms 15 ppm or below. This is the only place the clean-ballast definition reaches for a number, and it is the same 15 ppm threshold that governs machinery-space discharge under Regulation 15.
Segregated ballast (Regulation 1.18) is a different concept. It is “the ballast water introduced into a tank which is completely separated from the cargo oil and oil fuel system and which is permanently allocated to the carriage of ballast.” The key word is “completely.” Segregated ballast never shares piping or pumps with the cargo or fuel oil, so it cannot become contaminated in normal service. Clean ballast can be discharged through monitoring; segregated ballast is clean by construction, because the system that holds it has no connection to oil at all. The segregated-ballast-tank requirements, which size and arrange these tanks so that a tanker need not carry ballast in cargo tanks, live in Regulation 18. The distinction is practical: a ship with segregated ballast tanks discharges ballast freely, while a ship relying on cleaned cargo tanks must run the ballast through the ODMCS and prove the 15 ppm figure each time.
Dimensions, deadweight, lightweight, and permeability
A cluster of definitions in Regulation 1 fixes the dimensional and capacity terms that the construction regulations use. They look mundane, but several of the construction and outflow rules turn on exact values, so the definitions have to be exact too.
Length (L) (Regulation 1.19) is “96 per cent of the total length on a waterline at 85 per cent of the least moulded depth measured from the top of the keel, or the length from the foreside of the stem to the axis of the rudder stock on that waterline, if that be greater.” This is the load-line length, the same L that the International Convention on Load Lines uses, and it is measured in meters. Breadth (B) (Regulation 1.22) is the maximum breadth measured amidships to the moulded line of the frame for a metal hull. These two feed the damage-stability and outflow calculations, where the tank arrangement is assessed against ship dimensions.
Deadweight (DW) (Regulation 1.23) is “the difference in tonnes between the displacement of a ship in water of a relative density of 1.025 at the load waterline corresponding to the assigned summer freeboard and the lightweight of the ship.” Lightweight (Regulation 1.24) is “the displacement of a ship in metric tons without cargo, fuel, lubricating oil, ballast water, fresh water and feed water in tanks, consumable stores, and passengers and crew and their effects.” The two are a pair: deadweight is summer displacement minus lightweight. The deadweight gates run through the Annex, the 20,000 tonnes deadweight threshold for segregated ballast, the 30,000 tonnes deadweight threshold for protective location of segregated ballast spaces, so the definition has to be unambiguous about the reference waterline (summer freeboard) and the reference density (1.025). The relationship between the two figures, and how they are derived from a ship’s hydrostatics, is treated in the lightweight versus deadweight article, and the underlying tonnage concepts in tonnage measurement. Note that deadweight here is a mass in tonnes, not the gross or net tonnage figures that drive certificate thresholds elsewhere; conflating the two is a common error.
Permeability of a space (Regulation 1.25) is “the ratio of the volume within that space which is assumed to be occupied by water to the total volume of that space.” Permeability enters the damage-stability and outflow assessments: when a tank is assumed flooded, only the permeable fraction of its volume admits water, so the assumed permeability changes the flooded volume and the resulting outflow or stability outcome. The Annex sets standard permeability values for different space types in the outflow and damage regulations, and Regulation 1.25 fixes what the ratio means. Anniversary date (Regulation 1.27) closes the dimensional cluster with a survey term: the day and month each year corresponding to the expiry date of the IOPP Certificate, the date around which the annual and intermediate surveys are scheduled.
Regulation 2: the scope switch
Regulation 2 is titled “Application,” and its first paragraph is the master rule for the whole Annex. Regulation 2.1: “Unless expressly provided otherwise, the provisions of this Annex shall apply to all ships.” The default is universal. Every ship is in scope unless a specific regulation says it is out. That framing matters because it puts the burden on the exception, not the rule. A ship is covered by Annex I unless its operator can point to express words excluding it.
The Annex does carry express exclusions and tailored regimes, and Regulation 2 itself holds several. The structure of the rest of Regulation 2 is a set of carve-ins and carve-outs that decide how the tanker rules reach ships that are not, on their face, oil tankers.
Non-tanker cargo spaces that carry oil in bulk
Regulation 2.2 is the most important carve-in. A ship that is not an oil tanker but is fitted with cargo spaces “constructed and utilized to carry oil in bulk of an aggregate capacity of 200 cubic metres or more” must apply a list of the tanker requirements to those spaces: Regulations 16, 26.4, 29, 30, 31, 32, 34, and 36. So a dry-cargo ship with a deep tank rigged to carry an oil parcel of 200 cubic meters or more picks up the cargo-area discharge controls of Regulation 34, the slop-tank and monitoring requirements, and the Oil Record Book Part II obligation for those spaces. There is a relief band: where the aggregate capacity is less than 1,000 cubic meters, the simpler Regulation 34.6 may apply in lieu of Regulations 29, 31, and 32, so a small parcel attracts the discharge rule without the full slop-tank and ODMCS fit-out. This is the provision that catches general cargo ships and offshore supply vessels carrying bulk oil parcels, and it is regularly missed because the ship is not “a tanker” in the operator’s mind.
Annex II cargoes, asphalt, and specific-trade tankers
Regulation 2.3 handles overlap with Annex II: where a cargo subject to Annex II is carried in a cargo space of an oil tanker, the Annex II requirements also apply. The two Annexes stack rather than displace each other when a tanker carries a noxious liquid substance.
Regulation 2.4 carves out asphalt and similar products. The slop-tank and monitoring requirements of Regulations 29, 31, and 32 do not apply to oil tankers carrying asphalt or other Annex I products that, by their physical properties, inhibit effective product-water separation and monitoring. For those cargoes the discharge control under Regulation 34 is met by retaining residues on board and discharging all contaminated washings to reception facilities. The logic is that an ODMCS cannot meaningfully monitor a cargo that will not separate from water, so the Annex substitutes a retain-and-land regime for the monitor-and-discharge regime.
Regulations 2.5 and 2.6 set up the specific-trade exemption. An oil tanker delivered on or before 1 June 1982 (as defined in Regulation 1.28.3) that is solely engaged in specific trades between ports of States Parties may be relieved of the Regulation 18 segregated-ballast requirements (Regs 18.6 to 18.8), but only where the loading ports have reception facilities adequate for all the ballast and tank-washing water, all ballast and washings are retained on board and transferred to those facilities with the Oil Record Book Part II endorsed by the competent Port State Authority, the Administration and the port States have agreed to the specific trade, and the IOPP Certificate is endorsed accordingly. The endorsement-and-reception-facility conditions are the price of the relief, and they are checked at port State control. The exemption is narrow and aging out as the pre-1982 fleet retires, but it shows how Regulation 2 ties a relief from a construction rule to an operational discipline backed by certificate endorsement.
Offshore platforms, FPSOs and FSUs: the Regulation 39 carve-in
Regulation 2 does not itself set the offshore-platform rules; it leaves them to Regulation 39, “Special requirements for fixed or floating platforms.” We name Regulation 39 here without linking it, because the dedicated article does not yet exist. Regulation 39.1 states that it applies to fixed or floating platforms including drilling rigs, floating production, storage and offloading facilities (FPSOs) used for the offshore production and storage of oil, and floating storage units (FSUs) used for the offshore storage of produced oil. Regulation 39.2 then makes those units comply with the Annex I requirements for ships of 400 gross tonnage and above other than oil tankers, with three modifications: they must be equipped as far as practicable with the oil filtering equipment of Regulations 12 and 14; they must keep a record of all operations involving oil or oily-mixture discharges; and, subject to Regulation 4, discharge of oil or oily mixture into the sea is prohibited except where the oil content without dilution does not exceed 15 parts per million. The “without dilution” phrase closes the obvious loophole of meeting 15 ppm by adding clean water. So an FPSO is regulated as a large non-tanker ship for produced-water and machinery purposes, at the same 15 ppm ceiling that governs machinery-space discharge under Regulation 15, rather than under the cargo-area tanker regime, even though it stores oil in bulk.
How the definitions drive the operative regulations
The two opening regulations earn their place because their words decide the numbers downstream. Three examples show the chain from definition to consequence.
The first is the accidental-oil-outflow ratio. Regulation 34 permits a tanker to discharge cargo-area oily mixture en route only if, among other conditions, the total quantity of oil discharged does not exceed a fraction of the cargo. For a tanker “delivered on or before 31 December 1979, as defined in regulation 1.28.1,” the fraction is 1/15,000 of the total quantity of the cargo of which the residue formed a part. For a tanker “delivered after 31 December 1979, as defined in regulation 1.28.2,” it is 1/30,000. The newer class gets the tighter limit, half the permitted total. The entire difference rides on Regulation 1.28: which delivery-date class the hull falls into decides whether 1/15,000 or 1/30,000 applies, and that classification was fixed by the four-limb contract/keel/delivery test discussed above. Change the keel-laying date and you change the permitted outflow.
The second is the cargo-side discharge distance. The same Regulation 34 conditions require that “the tanker is more than 50 nautical miles from the nearest land.” That single clause pulls in Regulation 1.10. In open water, 50 nautical miles is measured from the territorial-sea baseline. Off north-eastern Australia, it is measured from the Great Barrier Reef coordinate line, which sits far seaward of the baseline, so the effective no-discharge band is much wider. The discharge condition is one sentence; its meaning changes entirely with the definition it cites.
The third is the monitoring ceiling. Regulation 34’s instantaneous-rate condition, “not exceeding 30 litres per nautical mile,” is unintelligible without Regulation 1.12, which defines that rate as liters per hour divided by speed in knots. The ODMCS that enforces the limit computes precisely the quantity Regulation 1.12 defines, and the slop-tank and monitoring fit-out required to claim the discharge right is the same equipment that the Regulation 18 and Regulation 29 arrangements provide. Definition, monitoring instrument, and discharge condition are one system.
The pattern holds across the Annex. The deadweight definition in Regulation 1.23 decides whether a tanker crosses the 20,000-tonne segregated-ballast threshold; the major-conversion definition in Regulation 1.9 decides whether a retrofitted hull is pulled up to new-build standards; the oil-tanker definition in Regulation 1.5 decides whether a converted unit carries the Form B IOPP supplement. Regulation 1 is not a glossary appended for convenience. It is the set of switches that route every later rule to the right ship.
Limitations
This article states the formal text of Regulations 1 and 2 as consolidated in the revised Annex I (MEPC.117(52), in force 1 January 2007). Several caveats apply to any practical use of that text.
First, the consolidated text moves. MARPOL Annex I is amended regularly by MEPC resolutions, and a definition or application provision can be added, renumbered, or revised. The Arctic special-area provisions, the inclusion of the Oman and Southern South African areas, and various double-hull amendments all post-date the original revision. Always work from the current IMO consolidated edition for the ship’s flag and date, not from a summary, and check whether an amendment has changed the sub-paragraph numbering before citing “regulation 1.28.2” or any other specific reference.
Second, the definitions are Annex I definitions only. “Oil” in Annex I is not “oil” in every other instrument; the petrochemical carve-out to Annex II, and the separate definitions in Annex II, mean a substance can be governed by a different Annex than its chemistry suggests. Do not carry an Annex I definition into an Annex II or Annex VI question.
Third, flag and port states may implement the Annex through national regulations that add detail or stricter limits. The U.S. implementation in 33 CFR, for example, reproduces and in places extends the MARPOL definitions. Where a ship trades into a jurisdiction with its own implementing rules, the national text governs the enforcement, even where it tracks the Annex word for word.
Fourth, this article does not reproduce the full coordinate schedules for every special area or the complete four-limb text of every delivery-date class. The boundary coordinates and the contract/keel/delivery limbs run to several pages in the Annex, and a compliance decision must be made against the full primary text, not the summary here. Where a vessel sits close to a special-area boundary or a delivery-date cut-off, read the exact words and the exact coordinates.
Fifth, the specific-trade and asphalt provisions in Regulation 2 are narrow and conditional. They relieve a ship of a requirement only when every listed condition is met and the IOPP Certificate is endorsed accordingly. An unendorsed claim to an exemption is no exemption, and port State control will treat the ship as fully subject to the rule the operator believed was waived.
See also
- MARPOL Annex I: the topical overview of the oil-pollution annex
- MARPOL Convention: the parent instrument and its six annexes
- MARPOL Annex I Regulation 15: machinery-space discharge control
- MARPOL Annex I Regulation 34: cargo-area discharge control
- MARPOL Annex I Regulation 18: segregated ballast tanks
- MARPOL Annex I special areas
- International Oil Pollution Prevention Certificate
- Lightweight versus deadweight
- Tonnage measurement
- Port State control