If the vessel has not been assigned an IMO number or a Norwegian call sign prior to registration, these numbers will be allocated by/ via the Department of Ship Registration.

1. Which vessels are assigned IMO numbers?

According to IMO Resolution A.1117(30), the Scheme applies to ships of 100 gross tonnage and above, including fishing vessels, passenger ships of less than 100 gross tonnage, high-speed passenger craft and mobile offshore drilling units engaged on international voyages (SOLAS regulation V/19-1); and to all motorized inboard fishing vessels of less than 100 gross tonnage 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.
Excepted from this provision are barges, pleasure crafts and constructions mentioned in sections 33 and 39 of the Norwegian Maritime Code.

Legislation

2. Owner and ISM liable manager

ISM managers and registered owners of vessels of 100 GT and above engaged on international voyages are also assigned IMO identifications numbers.

3. Who assigns these unique identifiers?

IHS Maritime & Trade on behalf of the International Maritime Organization (IMO)