Okay, there are 33 tanks aboard, and no one thought to bring a gun?
I was thinking the same thing. It's not like these pirate ships can just "sneak up" on anyone in the open ocean. How difficult can it be to take these guys out when they get too close (assuming you have the weapons)?
Perhaps I am oversimplifying, but it seems that you really need to prepare for the possibility of pirates in that region by arming yourself and taking out any boat that gets too close.