Global Ship Number System
GSN Home » The Global Ship Numbering System » Global Ship Numbering Allocation

8-digit integers

  • 1xxxxxxx Reserved for future Lloyds Register use.
  • 2xxxxxxx Ships derived from the British Shipbuilding Database, i.e. British built merchant and warships generally post-1850, whose ID is a 5 or 6-digit integer. A subset is at:
  • 3xxxxxxx Ships derived from Norwegian Marbase, generally ships over 1000 tons grt or deadweight, worldwide.
  • 4xxxxxxx Ships derived from Lloyds Register Sea-Web database, i.e. merchant ships over 100 GRT existing in mid 1960s when LR numbers started, or later. The LR 7-digit number has been adopted by International Maritime Organisation as a worldwide ship identifier.
  • 5xxxxxxx Available for other Class Societies and (national) number assigning authorities who have computerised databases, e.g. with modern (non-oceangoing) vessels like inland waterways craft, fishing vessels and larger leisure craft.
  • 6xxxxxxx The majority of other ships, generally self-propelled seagoing, but without an LR ID and/or not on major databases like BSD or Marbase or Miramar. A number of relatively modest sized databases already exist, e.g. Canadian Mills List. Blocks can include naval or offshore vessels not already on any of the above, both current and historical. (Some of these now have unpublished LR IDs). Even including modest sized vessels from major navies like U S Navy, there are many fewer such vessels than merchant vessels. These ten million numbers could be allocated in smaller blocks to database owners wishing to be compatible with a wider GSN system, with the second/third digit indicating the actual source, e.g. 61xxxxxx, 62xxxxxx.
  • 7xxxxxxx Since it appears that little structured work has been done on pre-20th century wooden sailing ships, it would be useful to have this completely separate block for minor vessels generally, and encourage database creators and populators.
  • 8xxxxxxx Ships on the international Miramar database. Over 200000 vessels with IDs up to 7 digits often equal to the LR/IMO number for modern ships or based on the Official Number of the flag (with 1000000 added if British, 2000000 if USA, 3000000 if Swedish, 400000 if Japanese)
  • 9xxxxxxx Used for parallel numerical referencing and transitional entries, including dubious vessels to be checked as further information comes to light, or reserved blocks prior to data exchange between database creators, e.g. minor vessels not on BSD or Miramar. It is suggested that 91xxxxxx is reserved for databases based on British official numbers, 92xxxxxx based on American, 93xxxxxx Swedish, 94xxxxxx Japanese.

It is possible that a ship may appear on more than one database and potentially have two GSNs. If resources permit in future, it may be possible to create one single master list if creators are willing to export core data which would permit duplicates to be removed, without affecting the underlying database if it has fewer than 8 digits.

Database creators who wish to reserve blocks of numbers and apply them are invited to register with Prof Ian Buxton at:

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