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IMO Ship and Company Number Scheme

Setting Industry Standards

To maintain comprehensive and accurate databases IHS Markit has developed over a period of time a number of key strategic agreements with governmental and inter-governmental organisations. Agreements exist with the International Maritime Organization regarding the issuing of the IMO Ship Number, IMO Company Number and IMO Registered Owner Number. Further information on these numbering schemes, which are managed by IHS Markit on behalf of the IMO, can be found below.

In addition to this, IHS Markit has recently launched a new, versatile and expandable shiptype coding system. The new system takes coding to a new level of detail and was created to meet the demands of both a changing industry and the requirements of those wishing to perform either aggregated analysis or analysis on individual vessel types. The International Maritime Statistics Forum have given their support to the new system which is now being incorporated into our products. Further information can be found below.

Ship Identification Number Scheme

IHS Markit is the originating source for the International Maritime Organization (IMO) Ship Number and is the sole authority with responsibility for assigning and validating these numbers. The Numbers are issued from the global maritime databases maintained by IHS Markit and consist of a unique seven digit number. IHS Markit manages this Scheme on behalf of the IMO.

In the 20 years since the introduction of the Scheme, the IMO Ship Number has become a universal public reference for ships, and continues to be the unique ship identifier adopted in new systems, such as AIS and LRIT. The IMO ship identification number was adopted on the 19th November 1987 in accordance with IMO Resolution A.600(15), by utilising the then existing Lloyds Register Ship Numbering system. The Scheme was made mandatory for all solas vessels under SOLAS regulation XI-1/3.

The Scheme assigns IMO Ship Numbers to propelled, sea-going merchant ships of 100 GT and above, with the exception of the following: vessels solely engaged in fishing, 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 and wooden ships.

IHS Markit has extended the Scheme on a voluntary basis to include some of the above excluded shiptypes, and in particular fishing vessels and commercial yachts that meet solas requirements.

The number is inserted on Ship's Certificates listed in SOLAS regulation I/12. Under SOLAS regulation XI - 1/3, the IMO Ship Number is required to be permanently and visibly marked on the ship. Furthermore, IMO MSC/Circ.1142 and MEPC/Circ.425 refer to the marking of the ship's plans, manuals and other documents with the IMO Ship Identification Number, recommending that the originator of such plans, manuals and other documents ensure that the IMO Ship Number is marked on them prior to submission for approval by an Administration or a recognised organisation acting on its behalf.

In accordance with IMO Circular Letter 1886/Rev.3, IHSF issues IMO Ship Numbers at the confirmed order stage, and shipbuilders/shipowners are encouraged to provide details of all new orders to IHS Markit to facilitate the assignment of the LR/IMO Number at the earliest opportunity which, for the majority of ships, becomes the IMO ship identification number on completion.

The IMO Ship Number is assigned to the total or greater portion of the hull enclosing the machinery space which is the determining factor should additional sections be added.

The IMO number is never reassigned to another vessel.

IHS Markit issues IMO Ship Numbers free of charge to shipyards, shipowners/operators, administrations and classification societies on submission of a completed IMO number Request Form, which is available from Replies are normally dispatched within a few working days from receipt of each request. IHS Markit reserves the right to refuse to assign an IMO Ship Number until all identification criteria have been supplied and to make a charge for processing significant batch requests of numbers.

IHS Markit processes IMO Number receipts by strict rotation and it is recommended that applicants should forward requests at their earliest opportunity. Applications involving more than one ship are accepted on a single ship per form basis only.

IMO Ship Numbers can be obtained from IHS Markit products and services. The Equasis free public site is also a reliable source to view the IMO Ship Number ( This site is supplied with up to date fleet and owner information from the databases of IHS Markit.

IMO Unique Company and Registered Owner Identification Number Scheme

IHS Markit is the originating source for the IMO Company and Registered Owner Numbers and is the sole authority with responsibility for assigning and validating these numbers. The Numbers are issued from the global maritime databases maintained by IHS Markit and consists of a unique seven digit number. IHS Markit manages this Scheme on behalf of the IMO.

The Scheme was introduced in 2004 through the adoption of Resolution MSC.160(78), as a measure to enhance maritime safety, security and environmental protection, and to facilitate the prevention of maritime fraud. The Scheme adopted the then existing IHS Fairplay Company Numbering system.

The purpose of the Scheme is to assign a permanent number for identification purposes to each company and registered owner managing ships of 100GT and above engaged on international voyages. Flag Administrations may also involve ships in the Scheme not engaged on international voyages.

The Scheme becomes mandatory for solas vessels on 1 January 2009 through adoption by Resolution MSC.194(80) of the proposed new SOLAS regulation XI-1/3-1 on the company and registered owner identification number and draft amendments to SOLAS regulation XI-1/5 on the addition of the numbers to the continuous synopsis record (CSR). The Number for Companies will also be added to ISM and ISPS certificates following adoption of resolutions MSC.195(80) and MSC.196(80), respectively.

One number is issued to a company if it undertakes one or both of the following roles:

  • "Company" has the same meaning as in SOLAS regulation IX/1 (the DOC Company) and is the organisation on the DOC, SMC or ISPS certificate
  • "Registered Owner" is the owner specified on the ships certificate of registry issued by an Administration

The Number stays the same when a company changes its name, or if its ships are transferred to another flag. When companies merge, IHS Markit will assign the Number of the larger company to the new amalgamated entity, while the Number of the small entity will be frozen and not re-used. The Number remains unchanged, but unused, in the event a company and/or registered owner sells, or otherwise disposes, of its ship(s) and does not begin operating new ship(s). The number will remain unchanged in the event the company and/or registered owner, after having sold or otherwise disposed of its ships, renews ship management at a future date. IHS Markit maintains a history of Companies and Registered Owners of ships on its database.

IHS Markit adopts a Company Name-style Guide for recording company Names on its database. This is to ensure that the formats of names are consistent with language and character sets used by its software and the software of organisations to which it supplies data. However, for clarification, IHS Markit also records the name-style as supplied by administrations for registered owners whose company registration is in the national jurisdiction of the administration. This name-style is supplied as part of the electronic data exchanges between IHS Fairplay and Administrations which support the Scheme, formalised in IMO Circular Letter 2554/Rev.1.

IMO Numbers for companies and registered owners can be obtained from IHS Markit products and services or can be viewed on the free website Numbers for new companies, and amendments to existing companies, can also be requested through this site.

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