This subject was raised in a photo comment so for the benefit of new and possibly younger members I thought it should be displayed in the Forum as guidance.
The IMO number can in most cases be found in Equasis but be careful with the Miramar ID Number, sometimes it is a correct IMO but many quoted are ID Numbers used before the IMO was introduced.
http://www.imo.org/OurWork/Safety/Implementation/Pages/IMO-identification-number-scheme.aspxMiramar is an excellent website for older ships with very useful and accurate information provided but prior to 1986 please double check if in doubt.
The IMO Number is with the ship for its lifetime, irrespective of flag or name changes it is permanent to the ship.
This is only intended as guidance, I am sure there are members who can provide more detailed information.
Regards
Ken Smith
Webmaster
