MARPOL Annex I and the Oil Record Book Part I

MARPOL Annex I, titled the Regulations for the Prevention of Pollution by Oil, is the chapter of the International Convention for the Prevention of Pollution from Ships that governs how ships retain, process, transfer, and discharge oil. It entered into force on 2 October 1983 and requires the Oil Record Book Part I, the mandatory record of machinery-space oil operations defined in Regulation 17.

Annex I is the oldest annex of the convention and the one most heavily operated in a ship’s machinery space. It is amended through resolutions of the IMO Marine Environment Protection Committee, and its requirements are certified through the International Oil Pollution Prevention Certificate and inspected by Port State Control. The Oil Record Book Part I is the documentary trail that connects the daily operation of oil filtering equipment, sludge tanks, and bunkering lines to the discharge limits the annex sets.

Scope and structure of MARPOL Annex I

Annex I applies to oil in any form. Regulation 1.1 defines oil as petroleum in any form, including crude oil, fuel oil, sludge, oil refuse, and refined products other than petrochemicals subject to MARPOL Annex II. The breadth of that definition brings fuel oil, lubricating oil, hydraulic oil, and the residues of all of them within a single discharge-control regime. Regulation 1.3 defines an oily mixture as a mixture with any oil content, so even lightly contaminated bilge water falls within the discharge conditions of the annex.

The operational core of Annex I is a small set of discharge and equipment regulations. Regulation 14 requires oil filtering equipment meeting the 15 parts per million standard for ships of 400 gross tonnage and above, and Regulation 15 sets the five conditions under which machinery-space bilge water may be discharged overboard. Regulation 12 requires dedicated tanks for oil residue (sludge) and prohibits any piping that could discharge sludge directly overboard, other than to the standard discharge connection of Regulation 13. For oil tankers, Regulation 34 sets the cargo-area discharge criteria, including the limit of 30 litres per nautical mile under Regulation 34.1.5 and the total-quantity limit of 1/30000 of the cargo under Regulation 34.1.6, which are recorded in the Oil Record Book Part II under Regulation 36.

The Oil Record Book Part I requirement under Regulation 17

Regulation 17 requires the Oil Record Book Part I for machinery-space operations. It is the record that demonstrates the discharge, retention, and disposal rules of the annex were observed for every oil operation on board. Each operation in a defined category triggers an entry, and an entry that cannot be reconciled against the ship’s deck and engine logs or against a physical tank sounding is the starting point for most Port State Control deficiencies in this area.

The signing rule fixes responsibility for each entry. The officer in charge of the operation signs that operation, and the master signs each completed page, the discipline preserved in Regulation 17.4 for the paper book and in Regulation 17.5 for signatures. Regulation 17.3 requires entries in English, French, or Spanish, and, for a ship flying the flag of a State whose official language is none of these, also in the official language of the flag State. Under Regulation 17.6 the book is kept available for inspection and retained for three years after the last entry. The companion record for cargo and ballast operations on oil tankers is the Oil Record Book Part II, required by Regulation 36; the machinery-space treatment is covered in full in the Oil Record Book Part I guide.

Who must keep an Oil Record Book Part I

The Oil Record Book Part I is required on every ship of 400 gross tonnage and above and on every oil tanker of 150 gross tonnage and above. The readers of that book are consistent across the regime: the seafarer who makes and signs the entries, the superintendent and Designated Person Ashore who audit them under the ISM Code, the flag-State surveyor and classification-society auditor who type-approve the recording system, and the Port State Control officer who inspects the book against the IOPP Certificate and its supplement.

Operation codes A to I

The entries themselves are structured by the operation codes set out in Appendix III of Annex I. Each code corresponds to a category of machinery-space operation and carries a fixed list of item numbers, numbered 1 to 26, that the operator completes. A wrong code, a missing item number, or a quantity that does not reconcile against a sounding makes the entry deficient regardless of how the underlying operation was performed. The full reference is the Oil Record Book Part I operation codes A to I master index.

Oil residue (sludge), defined in Regulation 1.4, is concentrated waste oil from purifiers, filters, and drip trays; it cannot be processed through the 15 parts per million separator and is recorded under Code C when collected, transferred, incinerated, or landed ashore. Oily bilge water is recorded under Code D when discharged manually and Code E when discharged automatically. Bunkering of fuel or bulk lubricating oil is recorded under Code H. The retained quantity carried under Code C is a running on-board total that must reconcile with the physical sounding of the tank, and a divergence between the recorded figure and the gauged volume is among the most common Port State Control deficiencies.

The electronic Oil Record Book under MEPC.312(74)

Regulation 1.28 of Annex I, added by the 2020 amendments in Resolution MEPC.314(74), defines an Electronic Record Book as a device or system approved by the Administration used to electronically record the entries required by the convention in place of a paper record book. Regulation 17.4 permits such a device to replace the paper Oil Record Book Part I once the flag Administration has approved it.

The use of an electronic record book is governed by Resolution MEPC.312(74), the 2018 Guidelines for the use of electronic record books under MARPOL, adopted on 17 May 2019 and entered into force on 1 October 2020. The guidelines set the expectations a flag-approved system meets for data integrity, electronic signatures, correction through an audit trail rather than a line-through, backup, and inspection access. An electronic Oil Record Book that meets these guidelines is documented in the electronic Oil Record Book article, and the wider framework is covered in the electronic record books cluster.

Port State Control inspection of the Oil Record Book

Regulation 11 provides the control mechanism under which a Port State Control officer inspects a foreign ship for compliance with the annex. The officer reads the Oil Record Book against the IOPP Certificate and its Form A supplement for ships other than oil tankers or Form B supplement for oil tankers, set out in Appendix II, and traces the recorded entries against the installed equipment, the alarm history of the oil filtering equipment, and the physical soundings of the sludge and bilge holding tanks.

The deficiencies the officer looks for are concrete: missing entries, unsigned pages, wrong operation codes, and recorded quantities that do not match physical soundings. Inoperative 15 parts per million oil filtering equipment, the absence of the Oil Record Book, and gross discrepancies in the oil balance can rise to detainable deficiencies under the Paris and Tokyo Memoranda of Understanding on Port State Control. The inspection process and deficiency coding are covered in the Port State Control cluster.