Interacciones entre orcas y barcos

Since July there have been interactions between orcas and mainly sailing vessels around the Iberian Peninsula, as far as we know it all started in southern Spain. According to witnesses, normally the animals go around the vessel, and ram the hull, making the boat to turn some degrees and even breaking parts of the rudder. There have been cases also in Portugal, and now the interactions are concentrated in northern Spain. It is probably the same group that has been travelling up north, but unfortunately we don’t have pictures/videos which are good enough to confirm it, or even confirm to which population do they belong to.
It has been all over the news in Spain and Portugal, and now more broadly (The Guardian: https://amp.theguardian.com/environment/2020/sep/13/killer-whales-launch-orchestrated-attacks-on-sailing-boats?__twitter_impression=true&s=09). We have no clue what could be the motivation of the whales to behave like this, for this reason it would be really helpful if we could get any input from other places, where those types of interactions between boats and killer whales have been happening before. So can you please contact me if you have any info on something similar?. We would really appreciate it. 
Kind Regards,
Ruth