That sounds like a lot of fun.
Do you know the game Graveyard (sometimes called Dead)? Campers lay on the ground (or sit, not moving), and have to resist moving. As soon as they move, they are 'out', and get to help the gravekeeper try and identify/persuade other movers. Good for downtime.
There are about a bunch 'circle games' I can think of, most of which involve someone leaving and trying to figure out some sort of mystery (who is the wink murder, who has the object behind their back). "Darlin if you love me won't you please please smile". Google that one if you don't know it.
One really cool activity that I did with my campers was taking enough small rocks that everyone in the circle can have one, then getting them to study their rocks, note how it feels, what it looks like. Then you collect the rocks, and redistribute them around the circle. Campers pass them around until they recieve their rock again (or until they think they have it). My experience has been that most of the time they identify their rocks confidently. Since the activity came from a bible study, the moral is that everyone is unique and special in some way...but that doesn't have to necessarily be a bible study moral.
Depending on the age of the campers, or maybe at the end of the week, you might want to lead a 'circle check' with them at quiet time; asking about what their favorite thing about camp was, their least favorite thing. Only one person talks at a time and it is important that everyone listens to that person.
And since you are pirates I would totally plan a non-threatening raid of some sort on another cabin...perhaps you could do some sort of inverse-raid where you give them booty and treasures instead of taking it away? Something renegade.