Sounds like a great addition to the game, just thinking out laud here:
What does "Both ships must be sailing and near each other" mean, like the surrounding 8 cells of ship?
If the chase is limited to say 10 mins, how often can a ship change direction/speed?
How will the chase end if ship 1 goes to opposite direction then ship 2, timeout / cell spaceing?
If one ships wants to board and the other attack, which will be the "winning vote"?
Does attack hinder a boarding after a while?
I got probably 100 more questions, but i'll wait for your reply before asking more.
GREAT game