Definitions #
A permanent, unique seven-digit identifier assigned to each ship, used for tracking ownership and safety records.
Technical A unique Lloyd’s Register-issued identifier under SOLAS reg. XI-1/3, permanently assigned to vessels of 100 GT+ for maritime safety and security.
Example The surveyor checked the IMO Number stamped on the ship’s side before issuing the safety certificate.
Etymology #
Abbreviation of International Maritime Organization (IMO), which adopted the system in 1987 to replace the former Hull or Official Number.
Collocations #
- IMO Number assigned IMO编号已分配
- verify the IMO Number 核对IMO编号
- IHS Maritime database IHS海事数据库（用于查询船籍）
Real Business Examples #
- The crew must display the IMO Number on the hull and in the ship’s documents, per SOLAS Chapter XI-1.
- Before chartering, the operator verified the vessel’s IMO Number in the IHS Maritime database.
- The port state control officer found a discrepancy between the IMO Number given in the AIS and the one recorded in the registry.
Register & Variants #
- Register: formal
- BrE/AmE: 全球通用，缩写形式多用 AmE 单据
Synonyms & Antonyms #
- Synonyms: IMO identification number, Lloyd’s Register number (historical)
Common Errors #
- Using the IMO Number interchangeably with the MMSI (maritime mobile service identity) IMO Number is permanent and ship-specific; MMSI is a temporary radio call identity that may change with flag or equipment.
- Assuming the IMO Number is the same as the hull number The hull number is assigned by the builder, while the IMO Number is a global, administratively issued identifier.
Confusable Terms #
- MMSI vs IMO Number
- MMSI is a nine-digit radio identity used for AIS and DSC, which can change when the ship changes flag or owner; the IMO Number never changes.
Frequently Asked Questions
Can an IMO Number be changed after a ship is sold??
No, the IMO Number is permanently assigned to the hull regardless of ownership, flag, or name changes.
Where do I find the IMO Number on a ship??
It must be marked on the hull (often at the stern) and also stated in the ship’s certificate of registry.
Published: 2026-10-03 Category: Shipping