Why could a Killer Whale follow a ship?

A friend of mine told me a story about an orca, following his ship for 16 days during the course through Atlantic up to Gibraltar, where it turned back...
Only following, like playing, singing for all these nights, a "song" that was more like a baby cry...
I've heard that heavy ship noise could compromise the performance of some whales, but... to follow a ship for such a long period, in deep waters and for a single animal... is it typical? What the explanation could be?
Thanks!

Possibly associated it with food. Possibly thought the bottom of the boat was similar to a fellow whale, could explain the singing too. Possibly just down to curiosity, whales can be very inquisitive. Could always ask the whale :)

Orcas are very social mammals and often surface around ships. It is quite unusualy for this orca to be alone as they would normally be found in pods (groups), but this orca seems to be a transiet orca if it was found far off the coast lines... if so not much is known about their behaviour, most studies have been done on resident orcas. The 'baby sound' is just the orcas call/song it may have been separated from its pod for some reason, it mayalso be a juevenile that was simply playing around and the pod may have been in proximity but not visible to the eye... as transient orcas cover a lot of distance... hope this helps!