We describe some of the difficulties with keeping track of unique vessels
Duplicated Entries due to Unexpected Values
Sometimes, the messages we collect have some malformed fields or unexpected values due to any of the following reasons:
- Message corruption (somewhere in the message transmit/receive path)
- AIS equipment misconfiguration by the vessel captain
- Fields manually input by the vessel captain contain typos, shorthand notation, unexpected messages, etc.
Any of the above, especially if it results in an unexpected value for mmsi , imo , call_sign , or name , can make it difficult to identify whether the unexpected value is from an already identified vessel or a new vessel.
This can sometimes result in a single vessel getting multiple entries in the vessels database.
How Spire Sense accounts for duplicates
As of December 2017, less than 3% of MMSIs in the Vessels API have duplicate entries. The intelligence built within Spire Sense becomes increasingly able to determine a unique source of truth for ships in the ocean as it receives more AIS messages over time.