I haven't seen a visual Pirate activation in PvP before (like Turn the Tide or Elusive activating), but I've heard anecdotal evidence from various PvPers that the ability does in fact activate inside Sparring Chamber and Brawling Hall in certain areas of the playing field. It's tough to really trust that when there is no indication stats are changing, combined with the original text of the ability http://www.pirate101central.com/wiki/Ability:Pirate_(Rank_3) referring to "ships".

If it is in fact activating (whether intended or unintended), then the ability is very bugged out since we have no way of being aware other than feeling like we're hitting more than normal or doing a bit more damage than normal. I'd sure like to know when myself or my opponent has 50% more accuracy. That type of information is literally game changing.

https://www.pirate101.com/forum/the-spar-chamber/does-pirate-work-in-ranked-8ad6a4144f695690014f8a1e170a25ca?page=1

Ratbeard originally said that it was not supposed to activate in PvP, but was this ever changed?