For those who don't speak the pirate lingo, here is a translation of how you Keelhaul a Roman:

Now, how are we going to be able to keelhaul multiple Romans, multiple times? Well, that’s the easy part. What’s hard is getting those plumbers into a small barrel. You see, we put them in the barrel with a lot of air (at least we believe it will keep them breathing while they are pulled under the ship). Then you give us your Spanish silver coins and we have you choose which Roman you want to keelhaul. We then seal them up in the barrel and you have to shoot them down, so to speak. You take aim with these rotten potatoes (compliments of our friend in Idaho) and try to hit the target next to the barrel. If you hit the target, the barrel will fall into the water and be pulled under the ship. If you fail, you need to pay again for another turn.