Several tips for improving the naval aspect, especially with Privateers...
1. You can take cities with hidden units (not naval ones obviously).
2. Make privateers (3,1,6) or 2 if all movement as roads with different movement points for sea and ocean. Given them a (2,1,2) bombard ability, nothing major, but enough to hassle.
3. Make them appear with Education or Astronomy, as this will significantly increase their lifespan since the introduction of the Ironclad makes them useless. They still require saltpeter (Gunpowder), so it won't bring them out too early.
4. In doing all of these you'll see the Ai build lots of the blighters.
5. I also have Caravels out with Education, and Frigates and Galleons out with Navigation, thus making age of the sail more interesting.
I also have the equivalent of privateers on land in the form of the Outlaw (Feudalism). A (3,1,1) unit, similar to the swordsman but requires no iron. The Ai also uses these effectively for their period which keeps you on your toes in times of peace.
