Lookie:
Attachment 4236
Sadly, even with Rank 5 Broadsides, Chainshot Broadsides only dealt damage somewhere in the low 50s, and with Open Fire, low 70s.
Edit: And yes, this screenshot was taken just today. About two hours ago (as of when this post was made).
4/3 people on the ship, you ask? Disney has yet STILL to fix the broken ship capacity. It's been broken for over a YEAR! And yet they fixed such trivial bugs like wall bugs and empty Kingshead...