Some of the (likely) fixes look pretty weird, moving at a ridiculous speed, through land and sea in a straight line, only to reach a certain point and continue as if nothing had happened.
e.g. 8 June 2012 05:00 from western Sahara to English Channel, through Sahara, right the middle of Spain, parts of France.
Another on 9 May 2012 from Southeast Asia, straight through the south of India and right through the middle of Africa to somewhere on the Guinean Gulf in about half a day.
That sounds to me like those ships are missing transponder data for some reason, and the visualisation is extrapolating between to distant data points.
Not sure why this would be the case. Transponder turned off? Data missing for other reasons?
I've never seen a perfectly clean dataset of any significant size. Big datasets have all sorts of weirdness unless there was an extraordinary effort to keep them pristine.
