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IMO number

IMO number is a mathematics topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand IMO number rather than just read about it. In short: The IMO number of the International Maritime Organization is a generic term with two distinct applications: the IMO ship identification number is a unique ship identifier; or, the IMO company and registered owner identification number is used to identify uniquely each company and/or registered owner managing ships of at least 100 gross tons (gt). The schemes are managed in parallel, but IMO company/owner numbers may…

IMO number — main illustration
IMO number — illustration

Key takeaways

  • IMO number belongs to mathematics; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect IMO number to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of IMO number from memory before moving on to harder problems.

Reference excerpt

The IMO number of the International Maritime Organization is a generic term with two distinct applications:

the IMO ship identification number is a unique ship identifier; or, the IMO company and registered owner identification number is used to identify uniquely each company and/or registered owner managing ships of at least 100 gross tons (gt). The schemes are managed in parallel, but IMO company/owner numbers may also be obtained by managers of vessels not having IMO ship numbers. IMO numbers were introduced to improve maritime safety and reduce fraud and pollution, under the International Convention for the Safety of Life at Sea (SOLAS). The IMO ship number scheme has been mandatory, for SOLAS signatories, for passenger and cargo ships above a certain size since 1996, and voluntarily applicable to various other vessels since 2013/2017. The number identifies a ship and does not change when the ship's owner, country of registry (flag state) or name changes, unlike the official numbers used in some countries, e.g. the UK. The ship's certificates must also bear the IMO ship number. Since 1 July 2004, passenger ships are also required to carry the marking on a horizontal surface visible from the air.

History

IMO resolutions (1987–2017) In 1987 the IMO adopted Resolution A.600(15) to create the IMO ship identification number scheme aimed at the "enhancement of maritime safety and pollution prevention and the prevention of maritime fraud" by assigning to each ship a unique permanent identification number. Lloyd's Register had already introduced permanent numbers for all the ships in their published register in 1963, and these were modified to seven-digit numbers in 1969. It is this number series that was adopted as the basis for IMO ship numbers in 1987.

Unique and permanent numbers are needed due to the frequent changes in ships' names or other details. As one example, the vessel with IMO ship number "IMO 9176187" was built in Japan, has been through the names Asia Melody, Cornelie Oldendorff, Maxima, Jaydee M, Evangelia, Evangeli, Shinsung Dream and Orange Dream, has operated under the flags of Panama, Liberia, Marshall Islands, the Republic of Korea and Sierra Leone, with numerous different owners/operators, and has had home port of Majuro, Freetown and Cheju, but its IMO number has remained unchanged throughout. The original resolution applied to cargo vessels (meaning "ships which are not passenger ships") of at least 300 gt and passenger vessels of at least 100 gt. This resolution was revoked in 2013, being replaced by Resolution A.1078(28), which allowed application of the Scheme to ships of 100 gt and above, including fishing vessels. That in turn was revoked in 2017 and replaced by Resolution A.1117(30), which allows its application to ships of 100 gt and above, "including fishing vessels of steel and non-steel hull construction; passenger ships of less than 100 gt, high-speed passenger craft and mobile offshore drilling units [...]; and all motorized inboard fishing vessels of less than 100 gt down to a size limit of 12 metres in length overall (LOA), authorized to operate outside waters under the national jurisdiction of the flag State". IMO resolutions are "for implementation on a voluntary basis". Although not mandatory under SOLAS, since IMO ship numbers became available also to fishing vessels in 2013, some regional fisheries management organisations, the European Union and other organizations or states have made them mandatory for fishing vessels above a certain size.

SOLAS regulation (1994) SOLAS regulation XI-1/3 was adopted in 1994 and came into force on 1 January 1996, making IMO ship numbers mandatory for those countries that have ratified (or acceded to, accepted, approved, adopted, etc.) SOLAS. The IMO scheme and hence SOLAS regulation does not apply to:

ships without mechanical means of propulsion pleasure yachts ships engaged on special service (e.g. lightships, SAR vessels) hopper barges hydrofoils, air cushion vehicles floating docks and structures classified in a similar manner ships of war and troopships wooden ships.

Security enhancements 2002 In December 2002, the Diplomatic Conference on Maritime Security adopted a number of measures aimed at enhancing security of ships and port facilities. This included a modification to SOLAS Regulation XI-1/3 to require the IMO ship numbers to be permanently marked in a visible place either on the ship's hull or superstructure as well as internally and on the ship's certificates. Passenger ships should also carry the marking on a horizontal surface visible from the air. The enhanced regulations came into effect on 1 July 2004.

Company and Registered Owner Regulation 2005 In May 2005, IMO adopted a new SOLAS regulation XI-1/3-1 on the mandatory company and registered owner identification number scheme, with entry into force on 1 January 2009. The regulation provides that every ship owner and management company shall have a unique identification number. Other amendments require these numbers to be added to the relevant certificates and documents in the International Safety Management Code (ISM) and the International Ship and Port Facility Security Code (ISPS). Like the IMO ship identification number, the company identification number is a seven-digit number with the prefix IMO. For example, for the ship Atlantic Star (IMO 8024026), IMO 5304986 referred to the former ship manager Pullmantur Cruises Ship Management Ltd and IMO 5364264 to her former owner, Pullmantur Cruises Empress Ltd.

… excerpt ends here. Continue reading the full article.

Illustrations

IMO number: "IMO 8814275" on Eendracht
"IMO 8814275" on Eendracht
IMO number: Stern of Evangelia displaying "IMO 9176187"
Stern of Evangelia displaying "IMO 9176187"
IMO number: "IMO 9319466" on the helideck of M/S Finnmaid
"IMO 9319466" on the helideck of M/S Finnmaid

Worked examples

Example 1 — a first encounter with IMO number

Start with the simplest possible case. Write down what IMO number claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In mathematics, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to IMO number before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about IMO number ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of IMO number

In research
IMO number appears in mathematics research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses IMO number in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
IMO number is common in secondary-school and first-year university syllabi. It links to neighbouring topics IMO numbers, International Maritime Organization, Law of the sea, so understanding it makes those chapters shorter.
In everyday life
Look for IMO number outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study IMO number in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what IMO number means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain IMO number out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is IMO number in simple terms?

The IMO number of the International Maritime Organization is a generic term with two distinct applications: the IMO ship identification number is a unique ship identifier; or, the IMO company and registered owner identification number is used to identify uniquely each company and/or registered owne…

Why does IMO number matter?

Because it connects several mathematics ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study IMO number?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on IMO number.

Tags

  • IMO numbers
  • International Maritime Organization
  • Law of the sea
  • Ship identification numbers
  • Ship registration

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