Various numbers are assigned to a ship at different points during the registration/licensing process.
Hull number
This is the first number a ship receives. It is a sequential number assigned to the ship by the shipyard where the vessel is being built. For example, Fergusons (a Glasgow shipyard) are currently working on Hull 802, a duel-fuel ferry. Another Ferguson ship was 712, the CEFAS Endeavour. The yard will refer to the vessel by this name as she is being built. The hull number is sometimes referred to as the yard number and is rarely if ever referred to once a ship has left the yard.
The Official Number - Applying to the Register of Shipping and Seafarers
Application form MSF 5547 must be filled in by or on behalf of the ship owner. Once the ship has been assessed as being eligible for the UK flag, the owner must complete or provide the following:
Application to Register – MSF 4740 (A)
Declaration of Eligibility – MSF 4727
Bill of Sale (for existing ships) – MSF 4705
Copy of Certificate of Incorporation (if the owner is a body corporate)
UK Certificate of Survey for Tonnage & Measurement
International Tonnage Certificate (ITC69) - (for vessels >500 GT)
Builders Certificate (for new builds) - MSF 4743
Deletion certificate/transcript from the current register or a written undertaking to provide one within six weeks
Copy of the ship’s current Continuous Synopsis Record (for vessels >500 GT) - MSF 5623-C
Mortgage registration forms (if appropriate) - MSF 4736 and MSF 4737
Payment of £153 for 5 years
Once this has been received and processed, a Carving and Marking note will be issued to the owner/surveyor. This states how the vessel needs to be marked. Once the vessel has been marked as required this is verified by a third party (a Registered Organisation surveyor) and the note is completed and returned to the RSS; once this has been received by the RSS, the Certificate of Registry, giving the vessel her Official Number, can be issued.
Should a ship leave the British Register, her Official Number is reserved for her by the RSS and re-assigned to her should she return to the flag. She will receive a new Official Number, from whichever flag she joins, on flagging-in.
IMO number
The IMO (International Maritime Organisation) number is a 7-digit number preceded by the letters ‘IMO’; for example IMO7846724. It is applicable to passenger vessels and vessels over 100GT.
An IMO number is assigned by S&P Global Market Intelligence* at the confirmed order stage, on receipt of a completed IMO number request form. The issued IMO number becomes the ships IMO number on the laying of the keel and is assigned to the portion of the hull enclosing the machinery space. The IMO number is required to be permanently marked on the ships hull or superstructure, as well as internally.
The IMO number is fixed for the life of a ship; from construction to scrapping, regardless of changes of name, nationality and use. IMO numbers can be searched at equasis.org (registration required), which is based on S&P Global’s database.
*S&P Global Market Intelligence also assign IMO company and Registered Owner numbers, to companies and registered owners of ships >100GT respectively.
MMSI number and Callsign
Think of the MMSI (Maritime Mobile Service Identity) number as the ship’s phone number. It is a 9-digit number assigned to the vessel by OFCOM as part of the radio licensing procedure. OFCOM then inform the ITU (International Telecommunications Union) and the MCA, so that a search on the ITU MARS database (Maritime Access & retrieval system) will show the vessels details.
MMSI numbers can be used to call any other vessel, coastal station or group of vessels using DSC (Digital Select Calling).
A vessels Callsign is also assigned by OFCOM.
Callsign and MMSI number remain with a ship for life, regardless of changes of name or owner. If the radio license is not maintained the MMSI may be assigned to another vessel after five years.
Applications for vessel radio licenses are made using form OfW347, following the guidance on form Of168a. MMSI number and Callsign are issued at the same time.
MCAQs
Two similarly sized ships have their bows cut off just fwd of the collision bulkhead. Their bows are then swapped and welded back on. Which ship will retain which IMO number? Why?
Who issues the Official Number, and when?
Who issues the MMSI and Callsign and when?
Who issues the IMO number and when?
Can the ships Official Number change? When?
Can the MMSI number of a ship change?
Can the IMO number of a ship change?