What you’re witnessing is a self reported dataset from an international community (read as “unconcerned with The Protestant Work Ethic”) of ship captains and owners.
There are so many edge cases and oddities that the more you look the more you’ll find.
The moral of the story here is that you cannot accept AIS data, or any single data source, to be God’s Truth; you must always skeptical of the data before your eyes, lest you fall victim to “The Analyst’s Fallacy” (believing that the data presented is all the data there is) and create false stories in your mind.
Couldn't a more rational theory be that the data is essentially captured over VHF radio waves and there can be data loss due to things like gaps in capture ranges, faulty capture devices, faulty transponders, or even signal congestion?
There are so many edge cases and oddities that the more you look the more you’ll find.
The moral of the story here is that you cannot accept AIS data, or any single data source, to be God’s Truth; you must always skeptical of the data before your eyes, lest you fall victim to “The Analyst’s Fallacy” (believing that the data presented is all the data there is) and create false stories in your mind.