IMO Number

A permanent seven-digit identifier assigned to a ship’s hull that stays fixed for the life of the vessel regardless of changes in name, flag, or owner. Established by IMO Resolution A.600(15) (1987) and made mandatory under SOLAS Regulation XI-1/3, the scheme is administered for IMO by IHS Maritime (now within S&P Global). The seventh digit is a check digit. It anchors port-state control records, casualty data, sanctions lists, and Lloyd’s List Intelligence ship histories.